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A novel, wearable, stretchable Smart Patch can monitor various aspects of physical activity, including the dynamics of running. However, like any new device developed for such applications, it must first be tested for validity and reliability. Here, we compare the step rate while running on a treadmill measured by this smart patch with the corresponding values obtained with the ”gold standard” OptoGait, as well as with other devices commonly used to assess running dynamics, i.e., the MEMS accelerometer and commercially available and widely used Garmin Running Dynamic Pod. The 14 healthy, physically active volunteers completed two identical sessions with a 5-minute rest between. Each session involved two one-minute runs at 11 km/h and 14 km/h separated by a one-min rest. The major finding was that the Smart Patch demonstrated fair to good test-retest reliability. The best test-retest reliability for the Running Pod was observed in connection with running at 11 km/h and both velocities combined (good and excellent, respectively) and for the OptoGait when running at 14 km/h (good). The best concurrent validity was achieved with the Smart Patch, as reflected in the highest Pearson correlation coefficient for this device when running at 11 or 14 km/h, as well as for both velocities combined. In conclusion, this study demonstrates that the novel wearable Smart Patch shows promising reliability and excellent concurrent validity in measuring step rate during treadmill running, making it a viable tool for both research and practical applications in sports and exercise science., Validerad;2024;Nivå 2;2024-05-21 (joosat);Full text license: CC BY-NC-ND 4.0;Funder: Slovenian Research and Innovation Agency under Research Core Funding (Grant P5-0147)

Multiple methods are available for patterning liquid metals, with distinct advantages and drawbacks. In this study, we focus on exploring the capabilities of digital non-contact deposition and patterning of liquid metal alloys (LMAs) to meet demands of contemporary production throughput. Our approach involves utilizing non-contact jet dispensing technology with a pneumatically-driven jet valve. The study focuses on evaluating how jetting frequency, fluid pressure, jetting pressure, and ball needle stroke length affect the size and shape of the final deposits. Based on this knowledge, we demonstrate the patterning and integration of jet-dispensed LMA interconnects into the design of a wearable patch for wireless monitoring of physiological ECG signal.

Applications of sensor nodes in our daily lives are increasing. Sensor nodes can be embedded in textiles to monitor various environmental parameters or to measure biomarkers. Embedded nodes in fabrics can use wires as means of communication. This approach, however, has drawbacks in terms of reliability, e.g. wire breaks, and discomfort that can arise in a large fabric network with multitudes of cables. Power-line communication (PLC) can mitigate these problems by using conductive planes instead of wires. However, the capacitance formed as a result of using two parallel plates and fabric in between attenuates the signal transmission between sensor nodes. Therefore, in order to compensate the attenuation effect of the conductive fabric which can be achieved by optimizing the hardware, we need to know the capacitance model of the conductive fabric. In our case it is necessary to know the capacitance model as a result of placing a cotton knit fabric between conductive meshes. In this work, we demonstrate that one can use the parallel plate capacitance model for estimating the capacitance of a cotton knit fabric placed between two conductive meshes.

The aim of the SINTEC Final Workshop “Smart Bioelectronic and Wearable Systems” is to highlight European research focused on the ultra-flexible, stretchable, soft and conformal technologies, and networking with companies and European funded projects to discover future opportunities in the stretchable electronics market. Topics include: Bioelectronics, Stretchable and conformal electronics, Wearable sensors and actuators, Smart patches and clothings, Wearables for sports and healthcare application, Intra-body communication, and Network solutions for wearable health and sport monitoring., SINTEC

By controlling the properties of its medium, supercooled liquid Ga (SLGa) based stretchable remains stretchable at -22 degrees C, i.e., 52 degrees C below its thermo-dynamic melting point of Ga. Thus far, our oldest deposited SLGa circuit and film have remained liquids for 2 years at room temperature. The study investi-gates the crystallization of SLGa triggered by the surface energy of nucleation agents, temperature, circuit cross-section, and mechanical impact. Based on these parameters, a method is presented to integrate electronic components with SLGa circuits without compromising its supercooling effect. Further, the large stiffness variation induced by phase transition is demonstrated in dif-ferent applications. For the desired stiffness variation, the crystallization rate can be controlled by varying the temperature and cross-section area. Finally, spray-printing an ink of microscale SLGa microscale particles can confor-mally pattern Ga on a rough surface, e.g., to fabricate a stretchable array of SLGa microelectrodes. A smart patch with stretchable SLGa electrode arrays records human electrocardiogram signals in cold water and does not stain the skin after use. Its low and stable impedance in water will enable novel applications in wearable electronics.

SINTEC

High-density interconnect (HDI) technology for liquid metal (LM)-based stretchable printed circuit boards is crucial for expanding their applicability. HDI technology provides high-resolution multilayer circuits with a high density of components, as required for next generation of neuroprobes and ultrasonic and sensor arrays. This study presents a HDI technique utilizing laser engraved micro grooves in silicone with a protective lift-off mask of polyvinyl alcohol (PVA) and subsequent microscale LM particle spray deposition. This approach achieves high-resolution LM patterns and enables multilayer connectivity and high-density integration of components simultaneously, that is, realizing HDI technology. It is demonstrated using a stretchable 0201 LED display with a density of six leads per mm2 and a cochlear implant (CI) electrode array. The demonstrated manufacturing of the CI has the potential to enable fully automated printed circuit board manufacturing of such implants with increased precision and throughput. Implants in guinea pigs show that the CI is capable of activating the auditory neuron with electrical auditory brainstem response (eABR) and electrical compound action potential (eCAP) of high quality. Moreover, the U-shaped cross section of the LM interconnects provides a higher mechanical shock resistance of the circuit than that of normal rectangular cross sections. A liquid metal based high-density interconnect technology that is capable of fabricating high resolution circuits and integrating electronic high-density components in multilayer stretchable system, which are demonstrated by a stretchable high-density integrated LEDs display and an eight-electroe array of a cochlear implant.image, Funding Agencies|Vetenskapsrdet [824984]; European Union [2017-03801]; Swedish Research Council

Integration of motor enzymes with biological nanopores has enabled commercial DNA sequencing technology; yet studies of the similar principle applying to solid-state nanopores are limited. Here, we demonstrate the real-life monitoring of phi29 DNA polymerase (DNAP) docking onto truncated-pyramidal nanopore (TPP) arrays through both electrical and optical readout. To achieve effective docking, atomic layer deposition of hafnium oxide is employed to reduce the narrowest pore opening size of original silicon (Si) TPPs to sub-10 nm. On a single TPP with pore opening size comparable to DNAP, ionic current measurements show that a polymerase-DNA complex can temporally dock onto the TPP with a certain docking orientation, while the majority become translocation events. On 5-by-5 TPP arrays, a label-free optical detection method using Ca2+ sensitive dye, are employed to detect the docking dynamics of DNAP. The results show that this label-free detection strategy is capable of accessing the docking events of DNAP on TPP arrays. Finally, we examine the activity of docked DNAP by performing on-site rolling circle amplification to synthesize single-stranded DNA (ssDNA), which serves as a proof-of-concept demonstration of utilizing this docking scheme for emerging nanopore sensing applications.

A novel wearable smart patch can monitor various aspects of physical activity, including the dynamics of running, but like any new device developed for such applications, it must first be tested for validity. Here, we compare the step rate while running in place as measured by this smart patch to the corresponding values obtained utilizing ''gold standard'' MEMS accelerometers in combination with bilateral force plates equipped with HBM load cells, as well as the values provided by a three-dimensional motion capture system and the Garmin Dynamics Running Pod. The 15 healthy, physically active volunteers (age = 23 +/- 3 years; body mass = 74 +/- 17 kg, height = 176 +/- 10 cm) completed three consecutive 20-s bouts of running in place, starting at low, followed by medium, and finally at high intensity, all self-chosen. Our major findings are that the rates of running in place provided by all four systems were valid, with the notable exception of the fast step rate as measured by the Garmin Running Pod. The lowest mean bias and LoA for these measurements at all rates were associated consistently with the smart patch.

Localized ectopic expression of enteroendocrine cells in fruit flies provides a convenient model for studying human intestinal diseases, e.g., inflammatory bowel disease, that need urgent attention. Due to its noninvasive feature, thermal activating ectopic expression is an excellent option, but it demands local heating of the tiny and delicate live flies’ abdomen (≈1 × 1 mm2) without blocking their breath, instead of global heating of the whole body. This work proposes a thin, high-resolution, and density liquid metal (LM) microheater with gas permeability and sufficient compliance to provide homogenous local heating to the fly's tiny abdomen. A depositing technique is developed that can make microscale thin (5 µm), smooth (Sa = 0.8 µm), gas permeable LM film for such microheater by introducing LM micrometer/sub-micrometer particles. Collision induced LM particle merging and hence sintering is proposed to solve low conductivity due to their particular shells of micrometer/sub-micrometer particles. The deposition can conformally print on the wavy or rough surface due to the fine particle size. With a shadow mask, this microscale deposition can enable high yield and reproducible thin LM patterning with high resolution, density, and precision simultaneously. Furthermore, it is demonstrated that epidermal patches can compliantly attach onto the wrinkle skin and fingerprint. Finally, by applying such a microheater on the fly abdomen, localized ectopic expression of enteroendocrine cells is successfully demonstrated.

A cochlear implant (CI) can restore sound perception for people with congenital or sensorineural hearing loss. Liquid metal (LM) based CI is more soft and complaint, enhancing its compliance and reducing intra-cochlear trauma, but the LM pattern demands high resolution. This work introduces a PCB manufacturing technique for high-resolution LM-based cochlear implant fabrication. It consists of laser cutting and ablation, masked LM microscale spray deposition, lift-off, and encapsulation. The microscale deposition is capable of patterning uniform LM at high resolution by fine spraying a sonication-produced LM particle based ink. A novel feature is that the laser-processable substrate is engraved when cutting the protective lift-off mask, avoiding mask transfer by lamination and allowing for alignment, vias, and higher aspect ratio structures, at high resolution. This feature simplifies the whole process and improves the precision and yield, allowing for more complex circuits. The fabricated CI shows good performance both in the inserting process and electrical signal.