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Abstract Wearable long-term monitoring applications are becoming more and more popular in both the consumer and the medical market. In wearable ECG monitoring, the data quality depends on the properties of the electrodes and on how they interface with the skin. Dry electrodes do not require any action from the user. They usually do not irritate the skin, and they provide sufficiently high-quality data for ECG monitoring purposes during low-intensity user activity. We investigated prospective motion artifact–resistant dry electrode materials for wearable ECG monitoring. The tested materials were (1) porous: conductive polymer, conductive silver fabric; and (2) solid: stainless steel, silver, and platinum. ECG was acquired from test subjects in a 10-min continuous settling test and in a 48-h intermittent long-term test. In the settling test, the electrodes were stationary, whereas both stationary and controlled motion artifact tests were included in the long-term test. The signal-to-noise ratio (SNR) was used as the figure of merit to quantify the results. Skin–electrode interface impedance was measured to quantify its effect on the ECG, as well as to leverage the dry electrode ECG amplifier design. The SNR of all electrode types increased during the settling test. In the long-term test, the SNR was generally elevated further. The introduction of electrode movement reduced the SNR markedly. Solid electrodes had a higher SNR and lower skin–electrode impedance than porous electrodes. In the stationary testing, stainless steel showed the highest SNR, followed by platinum, silver, conductive polymer, and conductive fabric. In the movement testing, the order was platinum, stainless steel, silver, conductive polymer, and conductive fabric.

Wearable long-term monitoring applications are becoming more and more popular in both the consumer and the medical market. In wearable ECG monitoring, the data quality depends on the properties of the electrodes and on how they interface with the skin. Dry electrodes do not require any action from the user. They usually do not irritate the skin, and they provide sufficiently high-quality data for ECG monitoring purposes during low-intensity user activity. We investigated prospective motion artifact–resistant dry electrode materials for wearable ECG monitoring. The tested materials were (1) porous: conductive polymer, conductive silver fabric; and (2) solid: stainless steel, silver, and platinum. ECG was acquired from test subjects in a 10-min continuous settling test and in a 48-h intermittent long-term test. In the settling test, the electrodes were stationary, whereas both stationary and controlled motion artifact tests were included in the long-term test. The signal-to-noise ratio (SNR) was used as the figure of merit to quantify the results. Skin–electrode interface impedance was measured to quantify its effect on the ECG, as well as to leverage the dry electrode ECG amplifier design. The SNR of all electrode types increased during the settling test. In the long-term test, the SNR was generally elevated further. The introduction of electrode movement reduced the SNR markedly. Solid electrodes had a higher SNR and lower skin–electrode impedance than porous electrodes. In the stationary testing, stainless steel showed the highest SNR, followed by platinum, silver, conductive polymer, and conductive fabric. In the movement testing, the order was platinum, stainless steel, silver, conductive polymer, and conductive fabric. [ABSTRACT FROM AUTHOR]

Introduction: The early detection of Huntington's disease (HD) can substantially improve patient quality of life. Current HD diagnosis methods include complex biomarkers such as clinical and imaging factors; however, these methods have high time and resource demands. Methods: Quantitative biomedical signaling has the potential for exposing abnormalities in HD patients. In this project, we attempted to explore biomedical signaling for HD diagnosis in high detail. We used a dataset collected at a clinic with 27 HD-positive patients, 36 controls, and 6 unknowns with EEG, ECG, and fNIRS. We first preprocessed the data and then presented a comprehensive feature extraction procedure for statistical, Hijorth, slope, wavelet, and power spectral features. We then applied several shallow machine learning techniques to classify HD-positives from controls. Results: We found the highest accuracy was achieved by the extremely randomized trees algorithm, with an ROC AUC of 0.963 and accuracy of 91.353%. Discussion: The results provide improved performance over competing methodologies and also show promise for biomedical signals for early prognosis of HD. [ABSTRACT FROM AUTHOR]

Introduction: The early detection of Huntington’s disease (HD) can substantially improve patient quality of life. Current HD diagnosis methods include complex biomarkers such as clinical and imaging factors; however, these methods have high time and resource demands.Methods: Quantitative biomedical signaling has the potential for exposing abnormalities in HD patients. In this project, we attempted to explore biomedical signaling for HD diagnosis in high detail. We used a dataset collected at a clinic with 27 HD-positive patients, 36 controls, and 6 unknowns with EEG, ECG, and fNIRS. We first preprocessed the data and then presented a comprehensive feature extraction procedure for statistical, Hijorth, slope, wavelet, and power spectral features. We then applied several shallow machine learning techniques to classify HD-positives from controls.Results: We found the highest accuracy was achieved by the extremely randomized trees algorithm, with an ROC AUC of 0.963 and accuracy of 91.353%.Discussion: The results provide improved performance over competing methodologies and also show promise for biomedical signals for early prognosis of HD.

Home sleep apnea testing (HSAT) without electroencephalography (EEG) recording is increasingly used as an alternative to in-laboratory polysomnography for the diagnosis of obstructive sleep apnea (OSA). However, without EEG, electrooculography (EOG), and chin electromyography (EMG) recordings, the OSA severity may be significantly underestimated. Although several ambulatory EEG systems have been recently introduced, no patient-applied systems including EEG, EOG, and chin EMG suitable for home polysomnography are currently in clinical use. We have recently developed and pre-clinically tested a self-applied ambulatory electrode set (AES), consisting of frontal EEG, EOG, and EMG, in subjects with possible sleep bruxism. Now, in this clinical feasibility study, we investigated the signal scorability and usability of the AES as a self-administered sleep assessment approach supplementing the conventional HSAT device. We also investigated how the diagnostic parameters and OSA severity changed when utilizing the AES. Thirty-eight patients (61 % male, 25–78 years) with a clinical suspicion of OSA conducted a single-night, self-administered HSAT with a portable polysomnography device (Nox A1, Nox Medical, Reykjavik, Iceland) supplemented with AES. Only one AES recording failed. The use of AES signals in data analysis significantly affected the median apnea-hypopnea index (AHI), increasing it from 9.4 to 12.7 events/h ( $p < 0.001$ ) compared to the conventional HSAT. Also, in eight patients, the OSA severity class changed to one class worse. Perceived ease of use was well in line with that previously found among healthy volunteers. These results suggest that the AES provides an easy, clinically feasible solution to record EEG as a part of conventional HSAT.

Abstract A novel energy‐efficient approach dedicated to high‐density implantable stimulators such as visual prostheses is presented. Energy efficiency of the approach proposed in this work is achieved through two ideas: the ‘tracking supply ribbon’ technique and ‘reverse charge pumping’. The proposed approach is implemented, in the multi‐channel case, in such a way that power efficiency of each stimulation channel is enhanced according to its specific voltage/current condition and independently from other channels. For this purpose, a multi‐channel power‐efficient charge pump circuit with small integrated capacitors is proposed. Based on the proposed approach, a fully integrated 16‐channel stimulation backend for a visual prosthesis was designed and simulated in the transistor level in a standard 0.18‐μm triple‐well CMOS technology, occupying 1.41 mm2 of silicon area. According to post‐layout simulation results, power savings of up to 74% for a single channel and 81.5% for multiple channels are achieved compared to the conventional output stage with a constant supply voltage. Designed for the proposed stimulation backend, the charge pump generates output voltages of 3.48 V, −1.69 V, −3.38 V, and −5.05 V out of a 1.8 V input voltage and exhibits average power efficiency of 92.8% and 86.8% for one‐ and three‐stage circuits, respectively, all in the case of a 100 μA current load. All the aforementioned results are based on post‐layout simulation. Moreover, a proof‐of‐concept prototype was developed using off‐the‐shelf components in order to demonstrate the operation of the proposed tracking supply ribbon idea.

Abstract In recent years, the electroencephalography (EEG) brain–computer interface (BCI) has been researched in the area of upper‐limb prosthesis control due to the promise of being able to record neurological signals which follow activation patterns in the cortex directly from the brain with non‐invasive electrodes. This is seen as a way of bypassing the limitation posed by acquiring neuromuscular signals predominantly with electromyography (EMG) directly from the stump, which possesses residual limb anatomy post‐amputation. In this study, the sequential forward selection algorithm to form a 10‐optimal‐channel representation, alongside an extended signal feature vector was applied, to investigate the motion intent decoding performance of EMG‐only, EEG‐only, and a fused EMG–EEG sensing configuration for four transhumeral amputees with varying stump lengths. The results showed a considerable improvement for the EMG‐only configuration with the advanced feature vector, but only a small increase for the EEG‐only, and thus a marginal improvement when information from both signals was fused together. This is likely due to the EEG requiring a greater number of channels spread across the skull to provide a reliable intent decoding. Further work will now involve optimisation studies to find a greater representation of electrode representation and parsimony, to minimise the number of channels while boosting motion intent decoding accuracy.

A significant percent of all global deaths are caused by cardiovascular diseases (CVD). The diagnostic of the electrocardiogram (ECG) is a clinical practice widely adopted to evaluate the heart condition and identify CVD. For long-term ECG monitoring, a biopotential acquisition system integrated in common clothing is a viable solution for telemedicine. The electrodes and wires play a major role in the comfort and signal quality acquired from the patient. The paper presents a technical solution, where stainless steel yarn was used to create a Lead I Einthoven system consisting of 3 dry electrodes embroidered on a sports shirt. There are novel electrode materials and techniques that push further the state-of-the-art in ECG acquisition, but the authors focused on the currently available materials that are low-cost, widely available and easily integrable into common clothing, in order to seek a simple yet fully functional solution with the potential to become a truly ubiquitous ECG monitoring system.

In response to the growing clinico-economic need for comprehensive home-based sleep testing, we recently developed a self-applicable facial electrode set with screen-printed Ag/AgCl electrodes. Our previous studies revealed that nocturnal sweating is a common problem, causing low-frequency artifacts in the measured electroencephalography (EEG) signals. As the electrode set is designed to be used without skin abrasion, not surprisingly this leads to relatively high electrode-skin impedances, significant impedance changes due to sweating and an increased risk of sweat artifacts. However, our recent electrochemical in vitro investigations revealed that the sweat artifact tolerance of an EEG electrode can be improved by utilizing an appropriate Ag/AgCl ink. Here we have investigated in vivo electrode-skin impedances and the quality of EEG signals and interference due to sweating in the population of 11 healthy volunteers. Commercial Ag and Ag/AgCl inks (Engineered Conductive Materials ECM LLC and PPG Industries Inc.) were used to test electrode sets with differently constructed ink layers. Electrode-skin impedances and EEG signals were recorded before and after exercise-induced sweating. There was extensive variation in the electrodeskin impedances between the volunteers and the electrode positions: 14.6-200 kΩ (PPG electrodes) and 7.7-200 kΩ (ECM electrodes). Sweating significantly decreased (p

Conductive Polymer Composites (CPCs) have recently gained an extensive scientific interest as feedstock materials in Fused Filament Fabrication (FFF) Three-dimensional (3D) printing. Polylactic Acid (PLA), widely used in FFF 3D printing, as well as its Carbon Black (CB) nanocomposites at different weight percentage (wt.%) filler loadings (0.5, 1.0, 2.5 and 5.0 wt.%), were prepared via a melt mixing filament extrusion process in this study and utilized to manufacture FFF 3D printed specimens. The nanocomposites were examined for their electrical conductivity. The highest loaded 3D printed CPC (5.0 wt.%) was tested as an electrothermal Joule heating device. Static tensile, flexural, Charpy's impact and Vickers microhardness mechanical properties were investigated for the neat and PLA/CB 3D printed nanocomposites. Dynamic Mechanical Analysis (DMA) revealed a stiffening mechanism for the PLA/CB nanocomposites. Scanning Electron Microscopy (SEM) elucidated the samples' internal and external microstructural characteristics. The PLA/CB 5.0 wt.% nanocomposite demonstrated also antibacterial properties, when examined with a screening process, against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). It can be envisaged that the 3D printed PLA/CB CPCs exhibited a multi-functional performance, and could open new avenues towards low-cost personalized biomedical objects with complex geometry, amongst others, i.e., surgery tools, splints, wearables, etc. [ABSTRACT FROM AUTHOR]

A fundamental limitation of the implantable brain-machine interfaces (BMI) is the wiring requirements for power transfer and signal transmission. Existing microelectrode technologies can only record from localized sections of the brain and require implantation of invasive electrodes through cranial surgeries. Here, we introduce a system-on-a-nanoparticle probe, a Neurophotonic Solution-dispersible Wireless Activity Reporter for Massively Multiplexed Measurements (Neuro-SWARM3), enabling remote detection of in vivo bioelectric signals. Neuro-SWARM3 offers five fundamental advancements simultaneously: (1) it enables use of infrared light within the biologically transparent near infrared (NIR-II, 1000–1700 nm) window for direct read-out through the skull, (2) it circumvents invasive surgical operations since no wiring or power supply is needed for the wireless (electro-plasmonic) excitation and remote detection, (3) due to its diminutive dimensions (<200 nm) that is comparable to viral particles, it can be delivered different regions of the brain without surgical operations, (4) as electro-plasmonic signal conversion removes front-end signal processing requirements, it opens the door to large scale in vivo measurements that are not restricted by electrode dimensions, physical wiring, and electronic bandwidth limitations, (5) by being much smaller than the critical dimensions that trigger glial cell response ($\sim 12~\mu \text{m}$), it offers a long term operation capability. As we show below, NeuroSWARM3 provides high signal to shot noise ratio (SSNR $\sim 10^{3}$) wireless recording capability from single neurons due to its enhanced scattering cross-section ($\sim 10^{4}$ nm $^{2}$) and field-sensitivity (up to ~40%). [ABSTRACT FROM AUTHOR]

The accurate diagnosis of sleep disorders requires an electroencephalography (EEG) recording. However, in-home EEG-based sleep monitoring has been hindered by the present cumbersome electrode systems which are impractical for patient self-application. To overcome this shortcoming, we recently introduced a self-applicable facial electrode set with screen-printed EEG electrodes. However, one remaining challenge in overnight EEG measurements is the presence of a low-frequency sweat artifact commonly occurring in sleep recordings. Here, the purpose was to improve the electrochemical properties of the electrodes so that they are more sweat tolerant. We selected three commercial Ag and Ag/AgCl inks (manufactured by Dupont, PPG, and ECM) for the fabrication of screen-printed electrode sets with differently shaped ink layers and compared their electrochemical properties. The open circuit potential and electrical impedance spectroscopy measurements were conducted in a custom-made electrochemical cell filled first with physiological saline and then with artificial sweat. Based on our measurements, the Ag/AgCl layer on top (i.e. in contact with the solution) mainly determines the electrochemical characteristics whereas the Ag layer underneath plays only a minor role. In artificial sweat, the ECM electrodes possessed the most satisfactory properties being very stable with the most reproducible impedance characteristics (standard deviations were significantly ($p

Long-term ECG (electrocardiogram) measurement in patients with burns is a complicated problem since the overlapping of surface contact electrodes can lead to additional injuries. The possibility of ECG recording in patients with burns using capacitive electrodes was not proved, and there are no models of the electrode contact with a patient’s body while rehabilitation means are used. In this paper, the model of the contact between capacitive electrodes and the skin was modified and the circuit model of the contact: skin – bandages (saline solution) – film – active capacitive electrode, was described. The influence of the parameters of a capacitive electrode on the frequency response of the contact of an electrode with skin was assessed. It was found that contact capacitance is crucial to obtain a high-quality ECG signal. The parameters of the impedance of bandages, saline solution, a dielectric film were calculated, and their effect on the frequency response was studied. Based on the modified model, the frequency response of contact was modeled taking into consideration all the calculated parameters; it was found that the resulting frequency response of the contact corresponds to the frequency range of the ECG signal. Analysis of the calculations proves the possibility of using capacitive electrodes when applying various rehabilitation means. It was found that at a change in the impedance of the saline solution from 0.1 gigaohms to 1 gigaohm, the changes in the frequency response of the contact are not crucial for the final quality of the received signal. All calculations were carried out by modeling in the Qucs environment (ngspice SPICE). Simulation results can be used in the development of new types of capacitive electrocardiographic electrodes. The proposed model can be used to study other wound covers, as well as to model physiological processes when putting artificial skin and wound covers. [ABSTRACT FROM AUTHOR]

Continuous monitoring of bladder activity during normal daily activities would improve clinical diagnostics and understanding of the mechanisms underlying bladder function, or help validate how differing neuromodulation strategies affect the bladder. This work describes a urological monitor of conscious activity (UroMOCA). The UroMOCA included a pressure sensor, urine impedance-sensing electrodes, and wireless battery recharge and data transmission circuitry. Components were assembled on a circuit board and encapsulated with an epoxy/silicone molded package that allowed Pt-Ir electrode feedthrough for urine contact. Packaged UroMOCAs measured 12 × 18 × 6 mm. UroMOCAs continuously transmitted data from all onboard sensors at 10 Hz at 30 cm range, and ran for up to 44 hours between wireless recharges. After in vitro calibration, implantations were performed in 11 animals. Animals carried the device for 28 days, enabling many observations of bladder behavior during natural, conscious behavior. In vivo testing confirmed the UroMOCA did not impact bladder function after a two-week healing period. Pressure data in vivo were highly correlated to a reference catheter used during an anesthetized follow-up. Static volume sensor data were less accurate, but demonstrated reliable detection of bladder volume decreases, and distinguished between voiding and non-voiding bladder events.

An electrocardiogram (ECG) records the electrical signal from the heart to check for different heart conditions, but it is susceptible to noises. ECG signal denoising is a major pre‐processing step which attenuates the noises and accentuates the typical waves in ECG signals. Researchers over time have proposed numerous methods to correctly detect morphological anomalies. This study discusses the workflow, and design principles followed by these methods, and classify the state‐of‐the‐art methods into different categories for mutual comparison, and development of modern methods to denoise ECG. The performance of these methods is analysed on some benchmark metrics, viz., root‐mean‐square error, percentage‐root‐mean‐square difference, and signal‐to‐noise ratio improvement, thus comparing various ECG denoising techniques on MIT‐BIH databases, PTB, QT, and other databases. It is observed that Wavelet‐VBE, EMD‐MAF, GAN2, GSSSA, new MP‐EKF, DLSR, and AKF are most suitable for additive white Gaussian noise removal. For muscle artefacts removal, GAN1, new MP‐EKF, DLSR, and AKF perform comparatively well. For base‐line wander, and electrode motion artefacts removal, GAN1 is the best denoising option. For power‐line interference removal, DLSR and EWT perform well. Finally, FCN‐based DAE, DWT (Sym6) soft, MABWT (soft), CPSD sparsity, and UWT are promising ECG denoising methods for composite noise removal. [ABSTRACT FROM AUTHOR]

Spinal cord injury (SCI) results in the inability to empty the bladder voluntarily, and neurogenic detrusor overactivity (NDO) and detrusor sphincter dyssynergia (DSD) negatively impact both the health and quality of life of persons with SCI. Current approaches to treat bladder dysfunction in persons with SCI, including self-catheterisation and anticholinergic medications, are inadequate, and novel approaches are required to restore continence with increased bladder capacity, as well as to provide predictable and efficient on-demand voiding. Improvements in bladder function following SCI have been documented using a number of different modalities of spinal cord stimulation (SCS) in both persons with SCI and animal models, including SCS alone or SCS with concomitant activity-based training. Improvements include increased volitional voiding, voided volumes, bladder capacity, and quality of life, as well as decreases in NDO and DSD. Further, SCS is a well-developed therapy for chronic pain, and existing Food And Drug Administration (FDA)-approved devices provide a clear pathway to sustainable commercial availability and impact. However, the effective stimulation parameters and the appropriate timing and location of stimulation for SCS-mediated restoration of bladder function require further study, and studies are needed to determine underlying mechanisms of action.

Advances in technology and improvement of efficacy for many neuromodulation applications have been achieved without understanding the relationship between the stimulation parameters and the neural activity which is generated in the nervous system. It is the neural activity that ultimately drives the therapeutic benefit and the advent of evoked compound action potential recording allows this activity to be directly measured and quantified. Closed-loop control adjusts the stimulation parameters to maintain a predetermined level of neural recruitment and has been shown to provide improved pain relief in individuals with spinal cord stimulators. However, no mechanism that relates more consistent neural recruitment to patient outcomes has been proposed. The authors propose a hypothesis that may explain the difference in efficacy between open- and closed-loop operational modes by considering the relationship between measured neural recruitment with hypothetical dose and side effect response curves. This provides a rational basis for directing clinical research and improving therapeutic systems.

Implantable motor neuroprosthetic systems can restore function to individuals with significant disabilities, such as spinal cord injury, stroke, cerebral palsy, and multiple sclerosis. Neuroprostheses provide restored functionality by electrically activating paralysed muscles in coordinated patterns that replicate (enable) controlled movement that was lost through injury or disease. It is important to consider the general topology of the implanted system itself. The authors demonstrate that the wired multipoint implant technology is practical and feasible as a basis for the development of implanted multi-function neuroprosthetic systems. The advantages of a centralised power supply are significant. Heating due to recharge can be mitigated by using an actively cooled external recharge coil. Using this approach, the time required to perform a full recharge was significantly reduced. This approach has been demonstrated as a practical option for regular clinical use of implanted neuroprostheses.

Deep brain stimulation (DBS) is an effective treatment for many people living with Parkinson's disease (PD). Although the primary treatment for PD is based on medications, disease progression eventually leads to inadequate symptom control. DBS provides benefits by alleviating motor dysfunctions such as muscle rigidity and tremor. DBS devices deliver electric pulse trains into specific brain regions via implanted electrodes. Existing DBS systems usually provide continuous stimulation with constant settings of parameters such as the amount of charge delivered per pulse. However, PD is characterised by fluctuations in the severity and frequency of impairments. DBS would be improved if stimulation settings were adjusted automatically in response to each patient's ever-changing needs. This requires a device incorporating sensing of signals that estimate the severity of motor impairment linked to an adaptive control algorithm that optimises therapeutic stimulation. Several types of signals are candidates for this function. Spontaneous local field potentials recorded by the DBS electrodes have shown promise in some experimental studies of adaptive DBS. More recently, DBS-evoked potentials have been reported. In particular, evoked resonant neural activity has properties including a larger amplitude than spontaneous potentials, suggesting it may be a suitable feedback signal to control adaptive DBS.

Neuroprosthetics aims at restoring impaired or lost neurological and mental functions by exploiting technological advances in implantable and wearable devices. The performance of implantable devices, such as neural interfaces, relies upon the synergy between biology and machines. Should this synergy lack, numerous undesirable consequences might occur, such as rejection, infection, or malfunctioning. Several material properties like softness, electrochemical behaviour, biocompatibility, and biodegradability are among the features affecting the reliability of neural interfaces. In this review, the authors describe modern polymeric substrates and organic-based electrodes, offering the best combination of such characteristics. Their versatility in merging different properties derives from the accessible control over their molecular structure and blending. Compared to inorganic materials, organic materials have superior mechanical compliance with the soft tissue, and conjugated polymers also have an advantageous electrochemical transport mechanism at the interface with electrolytic solutions, involving both ionic and electronic conductivities. Hence, all-polymer neural interfaces would be convenient for a multitude of benefits, including low-cost manufacturing, increased biocompatibility, lightweight, transparency, and affinity with green electronics. This review also highlights materials strategies supporting the development of safe electronic interfaces based on organic materials and beneficial for various applications neuroprosthetics.

Hybrid interfaces between living cells and organic conjugated polymers play a pivotal role in bioelectronics medicine. Currently, conjugated polymers are widely utilised for optical stimulation of living cells and other bio-interface applications such as neural probes, cellular scaffolds and biosensors for drug release. In such a work, the authors fabricated and characterised the Nano Photodiode array device for the subretinal implant. However, the authors did not discuss in their report about the biocompatibility of this new device. In this work, the authors manifest that the quintessential graphene electrode and polymer blend of semiconducting single-wall carbon nanotube and C(60) fullerene (S-SWCNT:C(60)) sustains its optoelectronic properties all through the various strides for neural preparation. Further, the studies show that these materials can provide a favourable environment for cell proliferation and a high degree of biocompatibility. PC-12 cells used as a valuable model to validate the biocompatibility were grown successfully onto the S-SWCNT:C(60) active layer still preserving its optical and electrical properties. The improved electrical performance of nano photodiode made of graphene, S-SWCNT:C(60) established in the previous studies and the excellent bio-interface performance of this nano photodiode shows that the nano photodiode array proposed by the authors is a strong candidate for subretinal implants.

In this work, we have applied optical emission spectroscopy diagnostics to investigate the characteristics of a non-thermal atmospheric pressure helium plasma jet. The discharge characteristics in the active and afterglow region of the plasma jet, that are critical for biomedical applications, have been investigated. The voltage-current characteristics of the plasma discharge were analyzed and the average plasma power was measured to be around 18 W. The effect of addition of small fractions of oxygen at 0.1%-0.5% on the plasma jet characteristics was studied. The addition of oxygen resulted in a decrease in plasma plume length due to the electronegativity property of oxygen. Atomic and molecular lines of selected reactive plasma species that are considered to be useful to induce biochemical reactions such as OH transitions A2Σ+(ν=0,1)→X2Π(Δν=0) at 308 nm and A2Σ+(ν=0,1)→X2Π(Δν=1) at 287 nm, O I transitions 3p5P→3s5S0 at 777.41 nm, and 3p3P→3s3S0 at 844.6 nm, N2(C-B) second positive system with electronic transition C3Πu →B3Πg in the range of 300-450 nm and N2+(B-X) first negative system with electronic transition B2Σu+→X2Σg+(Δν=0) at 391.4 nm have been studied. The atomic emission lines of helium were identified, including the He I transitions 3p3P0→2s3S at 388.8 nm, 3p1P0→ 2s1S at 501.6 nm, 3d3D→2p3P0 at 587.6 nm, 3d1D→2p1P0 at 667.8 nm, 3s3S1→2p3P0 at 706.5 nm, 3s1S0→2p1P0 at 728.1 nm, and Hα transition 2p-3d at 656.3 nm. Using a spectral fitting method, the OH radicals at 306-312 nm, the rotational and vibrational temperatures equivalent to gas temperatures of the discharge was measured and the effective non-equilibrium nature of the plasma jet was demonstrated. Our results show that, in the entire active plasma region, the gas temperature remains at 310 ± 25 K and 340 ± 25 K and it increases to 320 ± 25 K and 360 ± 25 K in the afterglow region of the plasma jet for pure helium and helium/oxygen (0.1%) mixture, respectively. Additionally, the vibrational temperatures range from 2200 ± 100 K and 2500 ± 100 K for pure helium and helium/oxygen (0.1%) mixture, respectively. The plasma jet was tested on heat sensitive polymer films used in biomedical applications such as polyethylene terephthalate and poly-L-lactide samples continuously for several minutes without causing any physical or thermal damage to the films. The plasma jet produces significant reactive species of interest while the gas temperatures remain very low demonstrating its potential for a range of biomedical applications. [ABSTRACT FROM AUTHOR]

In this study, the authors propose an innovative solution based on mantle cloaking method to restore the performance of an implantable antenna, which is degraded due to the scattering from an adjacent metallic body. In an implantable device, the metallic body is generally used as a house for electronic circuitry. Initially, they investigate the deteriorating effects of metallic body on the antenna input impedance and radiation characteristics. Finally, by covering the metallic body with the designed metasurface, most of the antenna parameters are successfully retrieved. The proposed model is fabricated and measured with the in vitro test by immersing the antenna inside a muscle emulating gel, as well as, inside the minced pork. [ABSTRACT FROM AUTHOR]

Fe3O4 with different shapes are reported herein to modify the glassy carbon electrode and then they are used to detect dopamine (DA), a member of the catecholamine and phenethylamine families. Cyclic voltammetry, electrochemical impedance spectroscopy, differential pulse voltammetry and linear sweep voltammetry are all chosen to characterise the sensor's performance to DA. Under the optimal conditions, the modified sensor (N‐rGO/Fe3O4 NRs/GCE) had some good performance, followed as short response time (∼3 s), wide linear range (0.2–176 μM), low detection limit (0.05 μM, S/N = 2), good stability and reproducibility. The fabricated DA biosensor was further investigated for DA determination in human blood serum, suggesting its great potential in biological samples. [ABSTRACT FROM AUTHOR]

This study presents an adaptive analogue calibration method to compensate electrode–skin impedance mismatch during biopotential signal (electrocardiogram, electroencephalogram and electromyogram) acquisition with enhanced immunity to electromagnetic interference (EMI). The method continuously measures the variation of the impedance mismatch between the electrode–skin interfaces arising primarily due to motion artefacts, and thereafter compensate for the resulting distortions at the output. The compensation is done with the help a proportional–integral–derivative controller in the feedback loop, together with the acquisition of the biopotential signals. A common mode shunt feedback at the output attenuates the common mode EMI and reduces the common mode deviation. As compared to previously reported techniques, the proposed technique refutes any need for offline manual calibration and shows a significant improvement in EMI attenuation without interrupting the main system's operation. This study explains the proposed technique with the comprising blocks, illustrates the theoretical models and analyses, and evaluates the superior performances of the proposed method by comparing the responses with those obtained from the other EMI‐Immune electrode mismatch compensating front‐ends existing in the literature. [ABSTRACT FROM AUTHOR]

Remote healthcare monitoring (RHM) is an emerging trend in the biomedical field that leverages on the advancement of Internet of Things (IoT) to enhance the coverage of healthcare services around the world. An RHM system with the electromyography (EMG) measurement capability has great potential in improving the efficiency of medical treatment and physical therapy for chronic inflammatory myopathies. Conventional EMG measurement is often invasive, complex and require an ever-present medical officer. This paper proposes a capacitive electromyography (CEMG) monitoring system to overcome the limitations of the contact EMG monitoring system by using the capacitive sensing methodology. The system architecture and circuit design are detailed in this paper and the hardware implementation with experimental results are presented. This CEMG monitoring system achieved extremely low noise floor of less than 2 mV. Its performance also highly correlates with the conventional wet contact electrode without requiring any post signal processing. Therefore, this CEMG monitoring system is ideal for remote healthcare monitoring applications. [ABSTRACT FROM AUTHOR]

This work proposes and computationally investigate the use of magnetic neural stimulation as an alternative to electrical stimulation to achieve selective activation of rat sciatic nerve. In particular, they assess the effectiveness of an array of small coils to obtain selective neural stimulation, as compared to a single coil. Specifically, an array of four mm-sized coils is used to stimulate rat sciatic nerve, targeting the regions of fascicles that are associated with different muscles of the leg. To evaluate the selectivity of activation, a three-dimensional heterogeneous multi-resolution nerve model is implemented using the impedance method for the computation of the magnetic and electric fields in the nerve. The performance metric ‘selectivity index’ is defined that measures the recruitment of the targeted region compared to other non-targeted regions of the nerve. The selectivity index takes values between −1 (least selective) and 1 (most selective). For each targeted region, a selectivity index of 0.75 or better is predicted for the proposed array configuration. The results suggest that an array of coils can provide superior spatial control of the electric field induced in the neural tissue compared to traditional extraneural electrode arrays, thus opening the possibility to applications where selective neurostimulation is of interest.

These days, the Internet of things (IoT) research is driving large-scale development and deployment of many innovative applications. IoT has indeed brought many smart applications to the doorstep of users. IoT has also made it possible to connect many sensors and control equipment. Here, the authors address an important application for physically challenged. The authors present a brain–computer interface (BCI) system to lock/unlock a wheelchair and control its movements using BCI. The approach presented here uses NeuroSky's MindWave Mobile, a single electrode electroencephalography (EEG) headset that can be connected to any Bluetooth-enabled system. The raw EEG data from the headset is processed on an Android mobile device to extract the electromyography (EMG) patterns that occur due to eye blinks and activity of muscles in the jaw. These patterns are used to control the movement of a wheelchair in all possible directions. A biometric security system is provided to lock and unlock the wheelchair by extracting the information about different brain waves from the raw EEG signal. In this system, only the user knows the password which is generated using brain waves and it can lock/unlock the wheelchair and control it. The proposed system was verified and evaluated using a prototype.

In this article, the design and development aspects of a compact bio‐potential measuring system, named ExGSense, is presented. Two versions of the prototype have been developed; first one can measure 3 + 1 V leads in time‐multiplexed fashion, while the other can measure 3 + 1 V leads simultaneously. This article also presents an efficient algorithm for filtering electrocardiogram signals which is required to attenuate the effect of motion artefacts which are inevitable in wearable systems. Further, a user‐friendly interface for PC and smartphone has also been developed. By the virtue of an ultra‐low noise instrumentation amplifier and the programmability of gain and bandwidth of the bio‐signal measuring system, a number of other bio‐potential signals like EMG, EOG and EEG have been successfully recorded using disposable, off‐the‐shelf wet Ag/AgCl electrodes. [ABSTRACT FROM AUTHOR]

This paper demonstrates that our developed beetle–computer hybrid legged robot achieves backward walk, which is impossible by intact beetles themselves in nature. Judging from the curvature of the natural leg spine, we hypothesized that the natural spine has an anisotropic function: the natural spine would provide foot traction only in forward walk but not in backward. The hypothesis was verified as beetles hardly walk backward due to often slips. We then designed an artificial leg spine, which isotropically functions in walk: the foot traction was increased and slipless walk was achieved in both backward and forward walk with the artificial spines being implanted into the beetle legs. For these investigations, a wireless communication device, or “backpack,” was mounted and wired to a live beetle for electrically stimulating leg muscles to remotely modulate leg motions and to perform the forward and backward walk on demand. Overall, the beetle hybrid robot revealed the anisotropic function of the natural leg spine and also achieved the backward walk, which the intact beetle cannot intrinsically perform. [ABSTRACT FROM AUTHOR]

This research work presents the design of the electronics modules of Adam's Hand, a transradial myoelectric prosthesis based on an innovative mechanism which can actuate five three‐phalanges fingers (15 degrees of freedom) with just one motor, instead of the five/six motors conventionally used in other prosthetic devices; moreover, the prosthesis uses two servomotors to actuate the wrist movements. Adam's Hand fingertips are provided with temperature and pressure sensors, while the user myoelectric signals are acquired wirelessly by means of the Myo armband, a wearable device provided with eight electromyography electrodes, a nine‐axis inertial measurement unit, and a transmission module. These data are received through an HM‐11 BLE module, connected to Adam's Hand custom PCB, which features an Arduino Micro board. This board processes all the data and drives the actuators by means of properly chosen drivers. A Raspberry Pi 3 board manages a touchscreen display – which can be used to visualise the gathered data – and sends them to a dedicate cloud platform, so that the orthopaedic technicians who take care of Adam's Hand users can monitor them in real time, thus improving their recovery during the rehabilitation period. [ABSTRACT FROM AUTHOR]

Direct current (DC) nerve block has been shown to provide a complete block of nerve conduction without unwanted neural firing. Previous work shows that high capacitance electrodes can be used to safely deliver a DC block. Another way of delivering DC safely is through a separated interface nerve electrode (SINE), such that any reactive species that are generated by the passage of DC are contained in a vessel away from the nerve. This design has been enhanced by using a high capacitance carbon “slurry” as the electrode in the external vessel to extend the capacity of the electrode (CSINE). With this new design, it was possible to provide 50 min of continuous nerve block without recharge while still maintaining complete recovery of neural signals. Up to 46 C of charge delivery was applied for a total of 4 h of nerve block with complete recovery. Because of the extended delivery time, it was possible to explore several properties of DC block that would not be revealed without the capability of a long-duration continuous block. It was possible to achieve complete block at lower values of DC if the block was applied for a longer period of time. Depending on the amount of charge applied during the block, the recovery was delayed for a period of time before complete force recovery was restored. These new properties provide novel techniques for device development to optimize charge delivery time and device powering concerns. [ABSTRACT FROM AUTHOR]

This paper presents an active microchannel neural interface (MNI) using seven stacked application specific integrated circuits (ASICs). The approach provides a solution to the present problem of interconnect density in three-dimensional (3-D) MNIs. The 4 mm2 ASIC is implemented in 0.35 μm high-voltage CMOS technology. Each ASIC is the base for seven microchannels each with three electrodes in a pseudo-tripolar arrangement. Multiplexing allows stimulating or recording from any one of 49 channels, across seven ASICs. Connections to the ASICs are made with a five-line parallel bus. Current controlled biphasic stimulation from 5 to 500 μA has been demonstrated with switching between channels and ASICs. The high-voltage technology gives a compliance of 40 V for stimulation, appropriate for the high impedances within microchannels. High frequency biphasic stimulation, up to 40 kHz is achieved, suitable for reversible high frequency nerve blockades. Recording has been demonstrated with mV level signals; common-mode inputs are differentially distorted and limit the CMRR to 40 dB. The ASIC has been used in vitro in conjunction with an oversize (2 mm diameter) microchannel in phosphate buffered saline, demonstrating attenuation of interference from outside the microchannel and tripolar recording of signals from within the microchannel. By using five-lines for 49 active microchannels the device overcomes limitations when connecting many electrodes in a 3-D miniaturized nerve interface. [ABSTRACT FROM AUTHOR]

One of the efficient methods in controlling the Parkinson's tremor is Deep Brain Stimulation (DBS) therapy. The stimulation of Basal Ganglia (BG) by DBS brings no feedback though the existence of feedback reduces the additional stimulatory signal delivered to the brain. So this study offers a new adaptive architecture of a closed‐loop control system in which two areas of BG are stimulated simultaneously to decrease the following three indicators: hand tremor, the level of a delivered stimulation signal in the disease condition, and the level of a delivered stimulation signal in health condition to the disease condition. One area (STN: subthalamic nucleus) is stimulated with an adaptive sliding mode controller and the other area (GPi: Globus Pallidus internal) with partial state feedback controller. The simulation results of stimulating two areas of BG showed satisfactory performance. [ABSTRACT FROM AUTHOR]

We report the fabrication of a polymer/enzyme‐based biosupercapacitor (BSC)/biofuel cell (BFC) hybrid device with an optimized cell voltage that can be switched on demand from energy conversion to energy storage mode. The redox polymer matrices used for the immobilization of the biocatalyst at the bioanode and biocathode act simultaneously as electron relays between the integrated redox enzymes and the electrode surface (BFC) and as pseudocapacitive charge storing elements (BSC). Moreover, owing to the self‐charging effect based on the continuously proceeding enzymatic reaction, a Nernstian shift in the pseudocapacitive elements, that is, in the redox polymers, at the individual bioelectrodes leads to a maximized open circuit voltage of the device in both operating modes. Comparison with a conventional fuel cell design, that is, using redox mediators with redox potentials that are close to the potentials of the used redox proteins, indicates that the novel hybrid device shows a similar voltage output. Moreover, our results demonstrate that the conventional design criteria commonly used for the development of redox polymers for the use in biofuel cells have to be extended by considering the effect of a Nernstian shift towards the potentials of the used biocatalysts in those pseudocapacitive elements. [ABSTRACT FROM AUTHOR]

Biofouling on surfaces compromises the function of biomedical devices whose function involves contact with biological fluids. In the context of electrochemical devices, proteins are attracted to the surface via coaction of various forces (hydrogen bond, hydrophobic effect, and other polar interactions) and protein interaction with the surface can significantly alter the surface chemistry. In response to this issue, we have developed an efficient anti‐biofouling surface that employs a glycoprotein, lubricin (LUB), and which generates low impedance layers compatible with electrochemical applications. Herein, we investigate how different LUB densities on platinum (Pt) electrodes affect the surface electrochemistry and its ability to prevent nonspecific adsorption of protein to the surface. Surfaces with higher densities of LUB were more resistant to protein adsorption. The LUB modified Pt electrodes were challenged in artificial perilymph (AP) media under passive and electrically stimulated conditions over 7‐day periods throughout which the LUB layer retained its anti‐biofouling and surface coating stability. LUBed up: a low‐impedance protein‐resistant surface is introduced, that consists of lubricin (LUB) coating onto a platinum surface. The LUB‐platinum interface presents a good resistance to nonspecific protein adsorption, remaining stable on the surface under passive or electrical‐stimulated conditions. [ABSTRACT FROM AUTHOR]

It is time for electrodes prepared from graphene oxide (GO) to replace the traditional electrodes. However, GO is an electrically insulating material. However, in this study, a conductive electrode was prepared from GO modification with glycerol (GL) under the esterification reaction at 90°C for 3 h with sulphuric acid as a catalyst under vacuum conditions. Polyvinyl alcohol (PVA) acts as a polymer host. It was mixed with GO and modification was carried out under heating conditions. The mixture of the GO/GL/PVA nanocomposite was rapidly cooled and poured into the electrode mould. Finally, it is placed in a desiccator at room temperature for two days. The characterisation (Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy) proved that the ester bond was formed and a complete distribution of GO/GL into the matrix of PVA was verified. The GO/GL/PVA nanocomposite was tested for electrocardiogram (ECG) electrodes. The biopic instrument was used to compare the behaviour of the GO/GL/PVA plastic electrode and the commercial one. The results indicated that the GO/GL/PVA plastic electrode efficiently detected ECG signals after two months with high conductivity and lower noise than the commercial electrode. The GO/GL/PVA plastic electrode has been reported for the first time in the literature. [ABSTRACT FROM AUTHOR]

Abstract Introduction Pelvic floor surface electromyography (sEMG) is often used in the assessment and treatment of individuals with pelvic floor abnormalities to measure muscle tone and neural control of the pelvic floor muscles (PFM); however, little is known about the role of the PFM in sexual arousal. Aim The aim of this pilot study was to examine whether changes in deep and superficial PFM activity—assessed with sEMG—can be observed during the presentation of sexual stimuli. Methods Deep PFM sEMG activity was assessed with a vaginal probe. Superficial PFM activity was assessed with sEMG electrodes placed over the bulbocavernosus and perianal muscles. 15 sexually healthy women (mean age 27 years) watched a series of neutral, anxiety-evoking, and sexually explicit films. Continuous subjective sexual arousal was measured using a handheld arousometer. Main Outcome Measure Changes in microvolts were measured by sEMG sensors, from neutral to anxiety-evoking and neutral to sexually explicit films. Results There was an increase in intravaginal and perianal sEMG for both the erotic and anxiety films. Bulbocavernosus sEMG responses did not differ among the 3 films. Concordance between self-reported continuous sexual arousal for the erotic film and bulbocavernosus sEMG (r = 0.349) was not significantly different than concordance using intravaginal sEMG (r = 0.293) or perianal sEMG (r = 0.236). Clinical Implications Understanding more about which parts of the PFM respond specifically to sexual stimuli may have implications for measuring the effects of treatments aimed at improving sexual response in women. Strength & Limitations The results of this pilot study provide a preliminary understanding of which pelvic floor muscles respond to sexual stimuli. A limitation of this study was the small sample size. Conclusion Taken together, these findings suggest that intravaginal and perianal sEMG respond to erotic stimuli, whereas bulbocavernosal sEMG responses do not. Hannan-Leith MN, Dayan M, Hatfield G, et al. Is Pelvic Floor Surface Electromyography a Measure of Women's Sexual Response? A Pilot Study. J Sex Med 2019;16:70–82. [ABSTRACT FROM AUTHOR]

Objective: Hand amputation is a highly disabling event, which significantly affects quality of life. An effective hand replacement can be achieved if the user, in addition to motor functions, is provided with the sensations that are naturally perceived while grasping and moving. Intraneural peripheral electrodes have shown promising results toward the restoration of the sense of touch. However, the long-term usability and clinical relevance of intraneural sensory feedback have not yet been clearly demonstrated.Methods: To this aim, we performed a 6-month clinical study with 3 transradial amputees who received implants of transverse intrafascicular multichannel electrodes (TIMEs) in their median and ulnar nerves. After calibration, electrical stimulation was delivered through the TIMEs connected to artificial sensors in the digits of a prosthesis to generate sensory feedback, which was then used by the subjects while performing different grasping tasks.Results: All subjects, notwithstanding their important clinical differences, reported stimulation-induced sensations from the phantom hand for the whole duration of the trial. They also successfully integrated the sensory feedback into their motor control strategies while performing experimental tests simulating tasks of real life (with and without the support of vision). Finally, they reported a decrement of their phantom limb pain and a general improvement in mood state.Interpretation: The promising results achieved with all subjects show the feasibility of the use of intraneural stimulation in clinical settings. ANN NEUROL 2019;85:137-154. [ABSTRACT FROM AUTHOR]

Flexible sheet electrode can record electrocorticography signals without penetrating the blood-brain barrier. However, the attachment between the cortex and the electrode influences the quality of the signal directly. Here, we present a 3-D ultrathin bioelectrode with elastic electrode sites to achieve conformal coverage on brain tissue and increase the flexibility of the electrode. Inspired by kirigami, the micro-warping elastic structures on the electrode can increase the conformality significantly when compared with the conventional planar electrodes. It has been proved that the warping structure has an excellent springback curve and maintains at least one week under the maximum stress of 7.5 kPa. Furthermore, the electrode sites were modified with platinum black to improve the electrochemical performance, and electrochemical characterization was performed. The electrode was compared with a plane onein vitro, which demonstrated the prominent attachment performance from the surface with sulci. Finally, the local field potential was recordedin vivo. [2018-0088] [ABSTRACT FROM AUTHOR]

Abstract Stainless steel (SS) has been widely used as a material for fabricating cardiovascular stents/valves, orthopedic prosthesis, and other devices and implants used in biomedicine due to its malleability and resistance to corrosion and fatigue. Despite its good mechanical properties, SS (as other metals) lacks biofunctionality. To be successfully used as a biomaterial, SS must be made resistant to the biological environment by increasing its anti-fouling properties, preventing biofilm formation (passive surface modification), and imparting functionality for eluting a specific drug or capturing selected cells (active surface modification); these features depend on the final application. Various physico-chemical techniques, including plasma vapor deposition, electrochemical treatment, and attachment of different linkers that add functional groups, are used to obtain SS with increased corrosion resistance, improved osseointegration capabilities, added hemocompatibility, and enhanced antibacterial properties. Existing literature on this topic is extensive and has not been covered in an integrated way in previous reviews. This review aims to fill this gap, by surveying the literature on SS surface modification methods, as well as modification routes tailored for specific biomedical applications. Statement of significance Stainless steel (SS) is widely used in many biomedical applications including bone implants and cardiovascular stents due to its good mechanical properties, biocompatibility and low price. Surface modification allows improving its characteristics without compromising its important bulk properties. SS with improved blood compatibility (blood contacting implants), enhanced ability to resist bacterial infection (long-term devices), better integration with a tissue (bone implants) are examples of successful SS surface modifications. Existing literature on this topic is extensive and has not been covered in an integrated way in previous reviews. This review paper aims to fill this gap, by surveying the literature on SS surface modification methods, as well as to provide guidance for selecting appropriate modification routes tailored for specific biomedical applications. Graphical abstract Unlabelled Image Highlights • Ongoing research aim to overcome inherent flaws of stainless steel and meet new application needs in biomedicine; • Metal properties are determined by the intended biomedical application; • Stainless steel has been modified with various functional groups through different linkers or physico-chemical techniques; • Surface modification is used to improve blood compatibility, osseointegration and anti-fouling properties. [ABSTRACT FROM AUTHOR]

Abstract Introduction Many studies have shown that electrostimulation of the cavernosal nerve can induce and maintain penile erection. Based on these discoveries, neurostimulation to activate the erectile response has been considered a potential solution to treat erectile dysfunction (ED). However, despite recognized potential, this technology has not been further developed. The barrier is the complex anatomy of the human cavernous nerve, which challenges the intraoperative identification of the cavernosal nerves for electrode placement. Aim To overcome this major barrier, we proposed a practical solution: a 2-dimensional flexible electrode array that can cover the entire plexus area, ensuring that at least 1 of the electrodes will be in optimal contact with the cavernosal nerve, without the need of intraoperative identification. The present study aims to evaluate this concept intraoperatively. Methods 24 patients enrolled for open radical prostatectomy were recruited. During the surgical procedures, the electrode array was positioned on the pelvic plexus (on the prostatic apex or pelvic wall) and electrical stimulation was applied to induce penile erection. Penile erectile response was assessed by (i) visual change of penile tumescence and (ii) by a penile plethysmograph system. Main Outcome Measure Ability and success rate of evoking penile response were measured by applying electrical stimulation using the developed electrode array. Results Electrical stimulation produced immediate penile response in all cases when tested before (on prostatic apex) or after prostate removal (on pelvic wall). Clear visual penile engorgement was observed in 75% of the cases, whereas 25% showed minimal to moderate penile tumescence. As expected, patients with lower International Index of Erectile Function-5 score presented a reduced response, whereas stimulation before prostate removal showed greater response than following removal. Interestingly, erectile response was potentiated by bilateral stimulation (circumference increase [mm]: 2.7 ± 1.02 vs. 8.2 ± 1.9, P =.01). Clinical Implications These data bring sufficient proof of concept of a conceivable novel medical implant for the treatment of ED caused by mechanical nerve injury, such as prostatectomy and spinal cord injury. Strength & Limitations This is the first approach that can ensure the optimal site stimulation of the erectogenic neuronal path within the lower pelvic area and overcome the major barrier of individual anatomic variability. However, because this study was performed intraoperatively in an acute scenario, further studies are needed to evaluate its chronic efficacy for clinical practice. Conclusion The flexible electrode array concept can ensure the electrostimulation of erectogenic neuronal path when positioned on the prostate apex or pelvic floor. Skoufias S, Sturny M, Fraga-Silva R, et al. Novel concept enabling an old idea: A flexible electrode array to treat neurogenic erectile dysfunction. J Sex Med 2018;15:1558–1569. [ABSTRACT FROM AUTHOR]

StereoElectroEncephaloGraphy (SEEG) is a minimally invasive technique that consists of the insertion of multiple intracranial electrodes to precisely identify the epileptogenic focus. The planning of electrode trajectories is a cumbersome and time-consuming task. Current approaches to support the planning focus on electrode trajectory optimisation based on geometrical constraints but are not helpful to produce an initial electrode set to begin with the planning procedure. In this work, the authors propose a methodology that analyses retrospective planning data and builds a set of average trajectories, representing the practice of a clinical centre, which can be mapped to a new patient to initialise planning procedure. They collected and analysed the data from 75 anonymised patients, obtaining 30 exploratory patterns and 61 mean trajectories in an average brain space. A preliminary validation on a test set showed that they were able to correctly map 90% of those trajectories and, after optimisation, they have comparable or better values than manual trajectories in terms of distance from vessels and insertion angle. Finally, by detecting and analysing similar plans, they were able to identify eight planning strategies, which represent the main tailored sets of trajectories that neurosurgeons used to deal with the different patient cases.

Stereoelectroencephalography is a surgical procedure used in the treatment of pharmacoresistant epilepsy. Multiple electrodes are inserted in the patient's brain in order to record the electrical activity and detect the epileptogenic zone at the source of the seizures. An accurate localisation of their contacts on post-operative images is a crucial step to interpret the recorded signals and achieve a successful resection afterwards. In this Letter, the authors propose interactive and automatic methods to help the surgeon with the segmentation of the electrodes and their contacts. Then, they present a preliminary comparison of the methods in terms of accuracy and processing time through experimental measurements performed by two users, and discuss these first results. The final purpose of this work is to assist the neurosurgeons and neurologists in the contacts localisation procedure, make it faster, more precise and less tedious.

Sacral nerve stimulation (SNS) is an established treatment for faecal incontinence involving the implantation of a quadripolar electrode into a sacral foramen, through which an electrical stimulus is applied. Little is known about the induced spread of electric current around the SNS electrode and its effect on adjacent tissues, which limits optimisation of this treatment. The authors constructed a 3-dimensional imaging based finite element model in order to calculate and visualise the stimulation induced current and coupled this to biophysical models of nerve fibres. They investigated the impact of tissue inhomogeneity, electrode model choice and contact configuration and found a number of effects. (i) The presence of anatomical detail changes the estimate of stimulation effects in size and shape. (ii) The difference between the two models of electrodes is minimal for electrode contacts of the same length. (iii) Surprisingly, in this arrangement of electrode and neural fibre, monopolar and bipolar stimulation induce a similar effect. (iv) Interestingly when the active contact is larger, the volume of tissue activated reduces. This work establishes a protocol to better understand both therapeutic and adverse stimulation effects and in the future will enable patient-specific adjustments of stimulation parameters.

The aim of this study was to investigate the use of inexpensive and easy-to-use hydrogel “marble” electrodes for the recording of electrical potentials of the human visual cortex using visual evoked potentials (VEPs) as example. Top hat-shaped holders for the marble electrodes were developed with an electrode cap to acquire the signals. In 12 healthy volunteers, we compared the VEPs obtained with conventional gold-cup electrodes to those obtained with marble electrodes. Checkerboards of two check sizes—0.8° and 0.25°—were presented. Despite the higher impedance of the marble electrodes, the line noise could be completely removed by averaging 64 single traces, and VEPs could be recorded. Linear mixed-effect models using electrode type, stimulus, and recording duration revealed a statistically significant effect of the electrode type on only VEP N75 peak latency (mean ± SEM: 1.0 ± 1.2 ms) and amplitude (mean ± SEM: 0.8 ± 0.9 µV) The mean amplitudes of the delta, theta, alpha, beta, and gamma frequency bands of marble electrodes were statistically significantly different and, on average, 25% higher than those of gold-cup electrodes. However, the mean amplitudes showed a statistically significant strong correlation (Pearson’s r = 0.8). We therefore demonstrate the potential of the inexpensive and efficient hydrogel electrode to replace conventional gold-cup electrodes for the recording of VEPs and possibly other recordings from the human cortex.