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Abstract Smoke detectors face the challenges of increasing accuracy, sensitivity, and high reliability in complex use environments to ensure the timeliness, accuracy, and reliability of very early fire detection. The improvement and innovation of the principle and algorithm for smoke particle concentration detection provide opportunities for improving the performance of the detector. This study represents a new refinement of the smoke concentration detection principle based on capacitive detection of cell structures, and detection signals are processed by a multiscale smoke particle concentration detection algorithm to calculate smoke concentration. Through experiments, it was found that the detector provides effective detection of smoke particle concentrations ranging from 0 to 10% obs/m; moreover, when the detection accuracy is greater than a certain number of parts per million (PPM), the sensitivity of the detector can reach the PPM level; furthermore, the detector can detect smoke particle concentrations higher than the PPM level accuracy even in an environment with a certain concentration of petroliferous and dust particles of different sizes.

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Surface Dial is a mass production PC accessory implementing a tangible interface for on‐and off‐screen interactions. It enables a dual‐handed interaction model in content creation tasks like drawing, video editing, presentation and data visualization. We delve into design considerations, including development of a capacitive approach for on‐screen detection and tracking. [ABSTRACT FROM AUTHOR]

Smoke detectors face the challenges of increasing accuracy, sensitivity, and high reliability in complex use environments to ensure the timeliness, accuracy, and reliability of very early fire detection. The improvement and innovation of the principle and algorithm for smoke particle concentration detection provide opportunities for improving the performance of the detector. This study represents a new refinement of the smoke concentration detection principle based on capacitive detection of cell structures, and detection signals are processed by a multiscale smoke particle concentration detection algorithm to calculate smoke concentration. Through experiments, it was found that the detector provides effective detection of smoke particle concentrations ranging from 0 to 10% obs/m; moreover, when the detection accuracy is greater than a certain number of parts per million (PPM), the sensitivity of the detector can reach the PPM level; furthermore, the detector can detect smoke particle concentrations higher than the PPM level accuracy even in an environment with a certain concentration of petroliferous and dust particles of different sizes. [ABSTRACT FROM AUTHOR]

17ß-Estradiol (E2) is an endocrine-disrupting chemical that has become a matter of concern across the globe for more than a decade due to potential health risks. This study reports facile methods to fabricate label-free aptasensor based on the non-Faradaic impedance mode using amine-functionalized graphene oxide polypyrrole (NH2-GO/PPy)-modified gold interdigitated electrode for direct capacitive detection of 17β-estradiol. The as-prepared NH2-GO/PPy nanocomposites have been successfully characterized by field-emission scanning electron microscopy (FESEM), atomic force microscopy, Fourier transform infrared spectroscopy, and electrochemical impedance spectroscopy. The results show that NH2-GO/PPy/IDE was able to detect E2 binding through aptamer conformational change by simply observing the capacitance change before and after immobilization. In addition, the biosensor showed a dynamic range of detection from 100 nM to 1 pM with a low detection limit of about 0.13 pM. The recoveries result also presented in this paper was validated using HPLC exhibited high sensitivity for bisphenol-A (BPA) detection and was successfully applied to detect E2 in real water samples with good recoveries. [ABSTRACT FROM AUTHOR]

Smoke detectors face the challenges of increasing accuracy, sensitivity, and high reliability in complex use environments to ensure the timeliness, accuracy, and reliability of very early fire detection. The improvement in and innovation of the principle and algorithm of smoke particle concentration detection provide an opportunity for the performance improvement in the detector. This study is a new refinement of the smoke concentration detection principle based on capacitive detection of cell structures, and detection signals are processed by a multiscale smoke particle concentration detection algorithm to calculate particle concentration. Through experiments, it is found that the detector provides effective detection of smoke particle concentrations ranging from 0 to 10% obs/m; moreover, the detector can detect smoke particles at parts per million (PPM) concentration levels (at 2 and 5 PPM), and the accuracy of the detector can reach at least the 0.5 PPM level. Furthermore, the detector can detect smoke particle concentrations at better than 1 PPM accuracy even in an environment with 6% obs/m oil gas particles, 7% obs/m large dust interference particles, or 8% obs/m small dust interference particles. [ABSTRACT FROM AUTHOR]

Smoke detectors face the challenges of increasing accuracy, sensitivity, and high reliability in complex use environments to ensure the timeliness, accuracy, and reliability of very early fire detection. The improvement in and innovation of the principle and algorithm of smoke particle concentration detection provide an opportunity for the performance improvement in the detector. This study is a new refinement of the smoke concentration detection principle based on capacitive detection of cell structures, and detection signals are processed by a multiscale smoke particle concentration detection algorithm to calculate particle concentration. Through experiments, it is found that the detector provides effective detection of smoke particle concentrations ranging from 0 to 10% obs/m; moreover, the detector can detect smoke particles at parts per million (PPM) concentration levels (at 2 and 5 PPM), and the accuracy of the detector can reach at least the 0.5 PPM level. Furthermore, the detector can detect smoke particle concentrations at better than 1 PPM accuracy even in an environment with 6% obs/m oil gas particles, 7% obs/m large dust interference particles, or 8% obs/m small dust interference particles.

The characteristics of real-time monitoring and flexible integration based on passive capacitive detection are becoming the preferred sensing strategy for wearable devices. However, the currently designed capacitive sensors mostly focused on the bionic microstructures to improve sensitivity and measurement accuracy, while ignoring the inherent mechanical wear and resistance of multilayer structures. In this paper, an integrated monolithic capacitive pressure detection based on room temperature liquid metal is designed and fabricated, avoiding the tightness problem of the multi-layer structure. The oxidized paste-like liquid metal owning superior interfacial wetting properties can stably adhere to the surface of the porous framework. The gas-filled porous framework endows the capacitive sensor with a mechanical response of 0.0557 g with a response and recovery time of 1.26 and 0.63 s under a load condition of 150 Pa, and steadily maintained in 1600 cycle tests. Finally, the capacitive sensor is employed to detect human physiological signals and force shock responses, which could clearly distinguish different action signals, providing a new platform for the subsequent development and design of integrated capacitive sensors. [ABSTRACT FROM AUTHOR]

Despite their high sensitivity and their suitability for miniaturization, biosensors are still limited for clinical applications due to the lack of reproducibility and specificity of their detection performance. The design and preparation of sensing surfaces are suspected to be a cause of these limitations. Here, we first present an updated overview of the current state of use of capacitive biosensors in a medical context. Then, we summarize the encountered strategies for the fabrication of capacitive biosensing surfaces. Finally, we describe the characteristics which govern the performance of the sensing surfaces, along with recent developments that were suggested to overcome their main current limitations. [ABSTRACT FROM AUTHOR]

Despite their high sensitivity and their suitability for miniaturization, biosensors are still limited for clinical applications due to the lack of reproducibility and specificity of their detection performance. The design and preparation of sensing surfaces are suspected to be a cause of these limitations. Here, we first present an updated overview of the current state of use of capacitive biosensors in a medical context. Then, we summarize the encountered strategies for the fabrication of capacitive biosensing surfaces. Finally, we describe the characteristics which govern the performance of the sensing surfaces, along with recent developments that were suggested to overcome their main current limitations.

We propose a new concept of photoacoustic gas sensing based on capacitive transduction which allows full integration while conserving the required characteristics of the sensor. For the sensor’s performance optimization, trial and error method is not feasible due to economic and time constrains. Therefore, we focus on a theoretical optimization of the sensor reinforced by computational methods implemented in a Python programming environment. We present an analytic model to optimize the geometry of a cantilever used as a capacitive transducer in photoacoustic spectroscopy. We describe all the physical parameters which have to be considered for this optimization (photoacoustic force, damping, mechanical susceptibility, capacitive transduction, etc.). These parameters are characterized by opposite trends. They are studied and compared to obtain geometric values for which the signal output and signal-to-noise ratio are maximized. [ABSTRACT FROM AUTHOR]

Electrochemical sensors based on antibody-antigen recognition events are commonly used for the rapid, label-free, and sensitive detection of various analytes. However, various parameters at the bioelectronic interface, i.e., before and after the probe (such as an antibody) assembly onto the electrode, have a dominant influence on the underlying detection performance of analytes (such as an antigen). In this work, we thoroughly investigate the dependence of the bioelectronic interface characteristics on parameters that have not been investigated in depth: the antibody density on the electrode's surface and the antigen incubation time. For this important aim, we utilized the sensitive non-faradaic electrochemical impedance spectroscopy method. We showed that as the incubation time of the antigen-containing drop solution increased, a decrease was observed in both the solution resistance and the diffusional resistance with reflecting boundary elements, as well as the capacitive magnitude of a constant phase element, which decreased at a rate of 160 ± 30 kΩ/min, 800 ± 100 mΩ/min, and 520 ± 80 pF × s(α-1)/min, respectively. Using atomic force microscopy, we also showed that high antibody density led to thicker electrode coating than low antibody density, with root-mean-square roughness values of 2.2 ± 0.2 nm versus 1.28 ± 0.04 nm, respectively. Furthermore, we showed that as the antigen accumulated onto the electrode, the solution resistance increased for high antibody density and decreased for low antibody density. Finally, the antigen detection performance test yielded a better limit of detection for low antibody density than for high antibody density (0.26 μM vs 2.2 μM). Overall, we show here the importance of these two factors and how changing one parameter can drastically affect the desired outcome. [ABSTRACT FROM AUTHOR]

In this study, the detection principle of the dual-coil multi-parameter impedance detection sensor is introduced, and the influence of the number of coil turns on the experimental results is studied. The author produces a series of dual-coil multi-parameter impedance detection sensors and builds an experimental detection platform. The test parameters are compared and analysed under different coil turns. The experimental results show that for the detection of inductive or capacitive parameters of the same pollutant detection particle, the amplitude of the inductance or capacitance parameter increases with the increase of the number of turns of the coil, and the signal-to-noise ratio also increases with the increase of the number of turns of the coil. Therefore, increasing the number of turns in the micro-plane coil helps improve the detection accuracy and signal-to-noise ratio of the impedance sensor. The results of the study show that the dual-coil multi-parameter impedance detection sensor can realise the identification and detection of pollutant particles, and it has certain practical significance for the new multi-parameter on-line oil differential detection. [ABSTRACT FROM AUTHOR]

Oil detection in mechanical equipment is a critical aspect of assessing the wear status of equipment. In this paper, we design a novel multi-pollutant detection sensor embedded in a high permeability material, which employs a radial channel detection method to improve the detection accuracy of metallic pollutants and non-metallic pollutants while maintaining the accuracy of detecting metallic wear particles. The experimental results demonstrate that the micro-triple-coil multi-pollutant detection sensor, based on a high-gradient magnetic field, can detect ferromagnetic particles, non-ferromagnetic particles, and moisture with high accuracy. The theoretical lower detection limit for ferrous particles is 38 µm, and for copper particles, it is 51 µm. Furthermore, the sensor successfully detects emulsified oil with 1% water content in the moisture detection experiment. Our proposed detection sensor provides a new reference direction for future oil detection sensor design and exhibits high accuracy. [Display omitted] • The magnetic field of the excitation coil is enhanced by a silicon steel sheet. • Sensor stability is further improved by utilizing a radial magnetic field. • Utilizes strong electric field areas to improve moisture detection accuracy. [ABSTRACT FROM AUTHOR]

Airborne metal particles (MPs; particle size > 10 μm) in workplaces result in a loss in production yield if not detected in time. The demand for compact and cost-efficient MP sensors to monitor airborne MP generation is increasing. However, contemporary instruments and laboratory-grade sensors exhibit certain limitations in real-time and on-site monitoring of airborne MPs. This paper presents a microfluidic MP detection chip to address these limitations. By combining the proposed system with microcirculation-based particle-to-liquid collection and a capacitive sensing method, the continuous detection of airborne MPs can be achieved. A few microfabrication processes were realized, resulting in a compact system, which can be easily replaced after contamination with a low-priced microfluidic chip. In our experiments, the frequency-dependent capacitive changes were characterized using MP (aluminum) samples (sizes ranging from 10 μm to 40 μm). Performance evaluation of the proposed system under test-bed conditions indicated that it is capable of real-time and continuous monitoring of airborne MPs (minimum size 10 μm) under an optimal frequency, with superior sensitivity and responsivity. Therefore, the proposed system can be used as an on-site MP sensor for unexpected airborne MP generation in precise manufacturing facilities where metal sources are used.

In this study, the detection principle of the dual-coil multi-parameter impedance detection sensor is introduced, and the influence of the number of coil turns on the experimental results is studied. The author produces a series of dual-coil multi-parameter impedance detection sensors and builds an experimental detection platform. The test parameters are compared and analysed under different coil turns. The experimental results show that for the detection of inductive or capacitive parameters of the same pollutant detection particle, the amplitude of the inductance or capacitance parameter increases with the increase of the number of turns of the coil, and the signal-to-noise ratio also increases with the increase of the number of turns of the coil. Therefore, increasing the number of turns in the micro-plane coil helps improve the detection accuracy and signal-to-noise ratio of the impedance sensor. The results of the study show that the dual-coil multi-parameter impedance detection sensor can realise the identification and detection of pollutant particles, and it has certain practical significance for the new multi-parameter on-line oil differential detection.

We propose a new concept of photoacoustic gas sensing based on capacitive transduction which allows full integration while conserving the required characteristics of the sensor. For the sensor’s performance optimization, trial and error method is not feasible due to economic and time constrains. Therefore, we focus on a theoretical optimization of the sensor reinforced by computational methods implemented in a Python programming environment. We present an analytic model to optimize the geometry of a cantilever used as a capacitive transducer in photoacoustic spectroscopy. We describe all the physical parameters which have to be considered for this optimization (photoacoustic force, damping, mechanical susceptibility, capacitive transduction, etc.). These parameters are characterized by opposite trends. They are studied and compared to obtain geometric values for which the signal output and signal-to-noise ratio are maximized.

Abstract Herein, we report the design of a novel label-free aptasensor based on ferrocene and silicon nanoparticles (SiNPs) for ultrasensitive detection of aflatoxin M1 (AFM1) in milk. Given that silicon nanomaterials stand out by their high capacitive power, we used them to develop a novel capacitive transduction system based on electrochemical capacitance spectroscopy (ECS). This strategy relies on the changes of the redox capacitance signal owed to the surface-tethered ferrocene film, by performing electrochemical impedance spectroscopy (EIS) measurements without using an external redox probe. The redox capacitance variation was found to correlate well with the increasing concentrations of AFM1 in the linear range from 10 to 500 fmol⋅L-1 with a sensitivity of 0.46 μF*fM-1*cm − 2. Furthermore, the aptasensor allowed to reach very low limits of detection and quantification equal to 4.53 fM and 14.95 fM, respectively. The platform revealed a high selectivity toward the target analyte, and it was applied to quantify very low concentrations of AFM1 in commercial pasteurized milk. Finally, the results of real sample analysis were successfully gauged against those obtained using commercially available enzyme-linked immunoassay (ELISA) kits. Graphical abstract fx1 Highlights • Development of a highly sensitive aptasensor for aflatoxin M1 detection in milk using a novel electrochemical capacitance spectroscopy approach. • This work highlights the first feasibility study of redox capacitance transduction (ECS) using screen-printed carbon electrodes (SPCE). • Detection of very low amounts of target (femtomolar range) with minimal interferences in real matrix. [ABSTRACT FROM AUTHOR]

A low noise interface ASIC for micro gyroscope with ball-disc rotor is realized in 0.5µm CMOS technology. The interface circuit utilizes a transimpedance pre-amplifier which reduces input noise. The proposed interface achieves 0.003°/s/Hz1/2 noise density and 0.003°/s sensitivity with ±100°/s measure range. The functionality of the full circuit, including circuit analysis, noise analysis and measurement results, has been demonstrated.

This paper presents the implementation of a system to capacitively self-sense the position of a comb drive based MEMS XY nanopositioner from a single common node. The nanopositioner was fabricated using the multi-users PolyMUMPs process, on which comb capacitors fringe fields are large and out of plane forces cause considerable deflection. An extensive analysis of the comb-drive capacitance including the levitation effects and its correlation to the measurements is presented. Each axis is independently measured using frequency division multiplexing (FDM) techniques. Taking advantage of the symmetry of the nanopositioner itself, the sensitivity is doubled while eliminating the intrinsic capacitance of the device. The electrical measured noise is 2.5 aF/ Hz , for a sensing voltage V sen = 3 V rms and f sen = 150 kHz, which is equivalent to 1.1 nm/ Hz lateral displacement noise. This scheme can also be extended to N-degree of freedom nanopositioners. [ABSTRACT FROM AUTHOR]

Pathogenic contamination of drinking water is critical in regard to human health. In this study, we investigated the electrical detection of single bacterium from drinking water. A microfluidics chip consisting of polydimethylsiloxane (PDMS) microchannel and gold microelectrodes was fabricated with conventional microfabrication techniques. Electrical characterizations were done with an LCR meter and the measurements were in good agreement with simulation results. The impact of channel and electrode dimensions was studied for the different type and size of particles, using both experimental and simulation techniques. In addition, the effect of excitation signal frequency and solution conductivity was analyzed employing both simulation and experimental methods. Finally, capacitive detection of a single Escherichia coli (E. coli) from drinking water was successfully carried out under optimum parameters and design geometries. [ABSTRACT FROM AUTHOR]

In silico evaluation of aptamer/target interactions can facilitate the development of efficient biosensor with high specificity and affinity. In this work, we present in silico , i.e. structural similarity, molecular docking and molecular dynamics selection of the aptamer with sufficient binding properties for acetamiprid (ACE), a nicotine-like pesticide, and its use to design aptamer–modified magnetic beads bearing ferrocene co–immobilized label for capacitive detection of ACE. Taking advantages of the aptamer higher stability and binding affinity, the specific properties of magnetic beads and the redox properties of ferrocene moiety, the developed aptasensor showed promising analytical performances for ACE detection, using electrochemical capacitance spectroscopy, with a linear response ranging from 1 fM to 100 pM and a limit of detection of 0.94 fM (S/N = 3). Furthermore, it was successfully applied to detect ACE in fortified tomatoes samples, proving a promising approach for routine detection of pesticide in real agricultural samples. [Display omitted] • Bioinformatics tools were used to choose between two aptamers with different lengths. • Knowledge-based choice allowed to select the shorter aptamer for the biosensor design. • Acetamiprid sensing is based on electrochemical capacitance spectroscopy. • The target was detected selectively in the 1 fM to 100 pM range. • The method was used to detect acetamiprid in fortified tomatoes sample. [ABSTRACT FROM AUTHOR]

Fused silica cylindrical resonant gyroscope (CRG) is a novel high-precision solid-wave gyroscope, whose performance is primarily determined by the cylindrical resonator’s frequency split and quality factor (Q factor). The laser Doppler vibrometer (LDV) is extensively used to measure the dynamic behavior of fused silica cylindrical resonators. An electrical method was proposed to characterize the dynamic behavior of the cylindrical resonator to enhance the measurement efficiency and decrease the equipment cost. With the data acquisition system and the designed signal analysis program based on LabVIEW software, the dynamic behavior of the fused silica cylindrical resonator can be analyzed automatically and quickly. We compared all the electrical measurement results with the optical detection by LDV, demonstrating that the fast Fourier transform (FFT) result of the resonant frequency measured by the electrical method was 0.12 Hz higher than that with the optical method. Thus, the frequency split measured by the electrical and optical methods was the same in 0.18 Hz, and the measurement of the Q factor was basically the same in 730,000. We conducted all measurements under the same operation condition, and the optical method was used as a reference, demonstrating that the electrical method could characterize the dynamic behavior of the fused silica cylindrical resonator and enhance the measurement efficiency.

This paper reports a novel capacitive sensing method, enabling accurate and self-calibrated measurements for both the amplitude and phase information in sinusoidal motion. The approach constructively utilizes the inherent nonlinearity of a triangular-electrode based (TEB) variable-area sense capacitor. In the case of TEB detection signal, two harmonics exist and each carries information about the motional amplitude and phase. The TEB method robustly extracts the motional amplitude from the ratio of two sideband amplitudes and extracts the motional phase from the subtraction of two sideband phases. This technique is especially valuable for capacitive detection of periodic motion in MEMS resonant devices, such as the resonant accelerometer and Coriolis vibratory gyroscope. The paper presents detailed theoretical analysis and proposes a real-time measurement algorithm implemented in an FPGA device. Experimental results manifest that, compared with the traditional linear method, the sensitivity of the measured amplitude and phase to system parameter variations is highly suppressed up to 95%. Furthermore, an oscillation control system with TEB capacitive detection is introduced for micro-machined vibratory gyroscopes. First measurement results show the amplitude variance of the drive displacement is 120 ppm in an hour while the phase variance is 80 ppm. Allan variance analysis indicates a bias instability of 6.5°/h for the gyroscope output. [ABSTRACT FROM AUTHOR]

Highly sensitive and selective detection of morphine is exhibited using a capacitive transducer coated with cathodically electropolymerized and molecularly imprinted poly( p aminostyrene). Through molecular imprinting, morphine-specific recognition sites have been fabricated throughout the film, which shows exceptional binding activity toward morphine based from electrochemical capacitance measurements. The thin film sensor has a linear response to morphine solutions with 20-40 × 10−6 m concentrations and a detection limit of 5.95 × 10−6 m. It demonstrates high selectivity toward morphine as compared to other analog molecules including nicotine and cholesterol. The formation of the polymer film is facilitated and monitored using electrochemical-quartz crystal microbalance and characterized by X-ray photoelectron spectroscopy. Infrared spectroscopy confirms the loading and removal of the analyte from the film. Based on molecular modeling calculations, strong hydrogen-bonding interactions between the monomer, cross-linker, and analyte form a stable pre-polymerization complex, which is critical in successfully imprinting morphine into the film and effective sensing of the analyte. [ABSTRACT FROM AUTHOR]

Several studies have been performed on the integration of biosensors into digital microfluidics (DMF). Despite the general success in their detection capabilities, there are still two challenges associated with the integration of biosensors into DMF: (1) complete removal of the droplet containing the analytes from the sensing surface; and (2) biochemical regeneration of the biosensor involving detaching the target analyte from the receptor after each round of sensing. The latter is case dependent and the solution can vary from one application to another. Our research aims at addressing the former, the solution to which is applicable to all biosensors integrated to DMF. This paper presents a thorough characterization of the hydrophilic surface of the biosensor in terms of wettability and geometry, taking into account the overall configuration of the DMF platform. Consequently, we identify the optimal geometry of the sensing surface and the DMF platform providing successful removal of the target droplet from the sensing surface after detection. Based on the results, the gap height is suggested to be chosen at the upper limit of the applicable range. Also, the biosensor, patterned on the device top plate, is recommended to be designed with a high aspect ratio and aligned with the center of the actuating electrode. As a proof of concept, the optimum configuration is implemented on a DMF platform with an interdigitated capacitive biosensor to detect different concentrations of Cryptosporidium , for which it is shown that the sample droplet is removed successfully from the superhydrophilic surface of the biosensor. [ABSTRACT FROM AUTHOR]

High-temperature-resistant inertial sensors are increasingly requested in a variety of fields such as aerospace, automotive and energy. Capacitive detection is especially suitable for sensing at high temperatures due to its low intrinsic temperature dependence. In this paper, we present high-temperature measurements utilizing a capacitive accelerometer, thereby proving the feasibility of capacitive detection at temperatures of up to 400 °C. We describe the observed characteristics as the temperature is increased and propose an explanation of the physical mechanisms causing the temperature dependence of the sensor, which mainly involve the temperature dependence of the Young's modulus and of the viscosity and the pressure of the gas inside the sensor cavity. Therefore a static electromechanical model and a dynamic model that takes into account squeeze film damping were developed. [ABSTRACT FROM AUTHOR]

Despite their high sensitivity and their suitability for miniaturization, biosensors are still limited for clinical applications due to the lack of reproducibility and specificity of their detection performance. The design and preparation of sensing surfaces are suspected to be a cause of these limitations. Here, we first present an updated overview of the current state of use of capacitive biosensors in a medical context. Then, we summarize the encountered strategies for the fabrication of capacitive biosensing surfaces. Finally, we describe the characteristics which govern the performance of the sensing surfaces, along with recent developments that were suggested to overcome their main current limitations.

In this study, we developed a compact and low-cost measurement system that can measure the real-time number concentration of airborne ultrafine particles (UFPs, particles smaller than 100 nm). Our system is based on the condensation nucleation method; however, it counts particles based on their electrostatic properties (i.e., dielectric constant) to overcome the limitations of complex optical systems that have traditionally been employed. The new system consists of two components: a microfluidic particle growth channel to grow UFPs into micron-sized water droplets and a capacitive particle counter to count the grown droplets. To effectively reduce the size and cost of the system, each system was fabricated into a single module using a semiconductor manufacturing process prior to integration. Super-hydrophilic micropillar wicks were monolithically integrated with Printed Circuit Board substrate channels to use water as the condensing working fluid. A glass substrate interdigitated electrode chip with a 3 μm gap was fabricated and placed on the impaction plate of an inertial impactor to be used as a sensor. Numerical calculations were performed to verify the dimensions of the channel required for efficient supersaturated vapor generation. Quantitative experiments using NaCl, (NH 4) 2 SO 4 , and Ag 2 O UFPs showed that our system could grow particles larger than 50 nm into micron-sized droplets and count up to 10,300 N cm−3 particles with linear electrostatic properties. • Our system is based on the condensation nucleation method; however, it counts particles based on their dielectric properties. • The chip-sized sensor capable of dramatically minimizing size/cost is promising candidates to replace CPC's optical system. • The performance of our system was evaluated compared to the reference equipment in indoor and outdoor environments. [ABSTRACT FROM AUTHOR]

Abstract: A new type of electronic nose is used to differentiate subspecies of flowers grown together under identical conditions. The electronic nose uses a computer-designed broadband voltage pulse sent to a polymer coated electromechanical resonator. The pulse spans a user-defined bandwidth around a user-selected center frequency so as to include at least one mechanical resonance. The transient voltage pulse excites mechanical resonance through the piezoelectric effect. The current response signal from the device is recorded and subjected to FFT. Components of the response due to electrical impedance and mechanical resonance are separated and tracked with time upon exposure to floral aromas from related species and subspecies. This work uses low-cost electronics but still achieves enough sensitivity to easily differentiate subspecies grown under identical conditions. [Copyright &y& Elsevier]

Abstract: The growing interest in personalized medicine leads to the need for fast, cheap and portable devices that reveal the genetic profile easily and accurately. To this direction, several ideas to avoid the classical methods of diagnosis and treatment through miniaturized and label-free systems have emerged. Capacitive biosensors address these requirements and thus have the perspective to be used in advanced diagnostic devices that promise early detection of potential fatal conditions. The operation principles, as well as the design and fabrication of several capacitive microsystems for the detection of biomolecular interactions are presented in this review. These systems are micro-membranes based on surface stress changes, interdigitated micro-electrodes and electrode–solution interfaces. Their applications extend to DNA hybridization, protein–ligand binding, antigen–antibody binding, etc. Finally, the limitations and prospects of capacitive microsystems in biological applications are discussed. [Copyright &y& Elsevier]

Abstract: Highly sensitive capacitive detection is reported for indoor air pollutants, e.g. formaldehyde, toluene, and ammonia gas, at room temperature using an electronic chip with self-oriented carbon nanotube microelectrode array. A remarkable capacitive response is observed owing to the dense entanglement of CNTs and the highly porous 3D structured CNT network on the surface of gold electrode. Such kind of nanotubes can be considered as extended and oriented electrodes. As compared with the effect of spray-casting MWCNTs, the relative capacitance change of the above-mentioned electronic chip is found to increase from 1.8 to 70 by taking ammonia as an example. A model is proposed to explain qualitatively the sensing mechanism of electronic chip. [Copyright &y& Elsevier]

A capacitive facial movement detection method designed for human–computer interaction is presented. Some point-and-click interfaces use facial electromyography for clicking. The presented method provides a contactless alternative. Electrodes with no galvanic coupling to the face are used to form electric fields. Changes in the electric fields due to facial movements are detected by measuring capacitances between the electrodes. A prototype device for measuring a capacitance signal affected by frowning and lifting eyebrows was constructed. A commercial integrated circuit for capacitive touch sensors is used in the measurement. The applied movement detection algorithm uses an adaptive approach to provide operation capability in noisy and dynamic environments. Experimentation with 10 test subjects proved that, under controlled circumstances, the movements are detected with good efficiency, but characterizing the movements into frowns and eyebrow lifts is more problematic. Integration with a two-dimensional (2D) pointing solution and further experiments are still required. [ABSTRACT FROM AUTHOR]

This paper reports a novel capacitive detection method, called the sideband-ratio (SBR) detection, which is robust to variations of such critical parameters as the nominal capacitance, frequency, and amplitude of the probing voltage and gain of the transimpedance amplifier. The approach constructively utilizes the inherent nonlinearity of parallel-plate sense capacitors in order to measure the amplitude of sinusoidal motion. In the case of parallel-plate detection signal, multiple harmonics exist and each carry information about the amplitude of mechanical motion. The SBR method robustly extracts the amplitude of motion from the ratio of multiple sidebands. This paper presents theoretical background and analysis of this nonlinear measurement method. A real-time measurement algorithm is implemented in software and simulated. Feasibility of the developed approach is demonstrated experimentally. [ABSTRACT FROM AUTHOR]

Abstract: Micro/nanomechanical resonators have been designed and fabricated with the aim to be used as distributed mass sensors for in situ measurement of the thickness of ultra-thin layers. First, we present a comparative study of three kinds of oscillating devices (cantilever, bridge and quad beam). The quad beam design has been selected for fabrication because it combines high sensitivity and good electrical response. The complete fabrication process of the device is based on electron beam lithography, lift-off and reactive ion etching. The frequency response has been characterized by means of electrical excitation and capacitive read-out. [Copyright &y& Elsevier]