sensing element
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Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 331
Author(s):  
Chung-Kun Yen ◽  
Karishma Dutt ◽  
Yu-Syuan Yao ◽  
Wen-Jeng Wu ◽  
Yow-Ling Shiue ◽  
...  

Polyvinylidene fluoride (PVDF) and AgNO3/PVDF composite piezoelectric fibers were prepared using near-field electrospinning technology. The prepared fibers are attached to the electrode sheet and encapsulated with polydimethylsiloxane to create an energy acquisition device and further fabricated into a dynamic sensing element. The addition of AgNO3 significantly increased the conductivity of the solution from 40.33 μS/cm to 883.59 μS/cm, which in turn made the fiber drawing condition smoother with the increase of high voltage electric field and reduced the fiber wire diameter size from 0.37 μm to 0.23 μm. The tapping test shows that the voltage signal can reach ~0.9 V at a frequency of 7 Hz, and the energy conversion efficiency is twice that of the PVDF output voltage. The addition of AgNO3 effectively enhances the molecular bonding ability, which effectively increases the piezoelectric constants of PVDF piezoelectric fibers. When the human body is exercised for a long period of time and the body is overloaded, the biceps muscle is found to produce 8 to 16 tremors/second through five arm flexion movements. The voltage output of the flexible dynamic soft sensor is between 0.7–0.9 V and shows an orderly alternating current waveform of voltage signals. The sensor can be used to detect muscle tremors after high-intensity training and to obtain advance information about changes in the symptoms of fasciculation, allowing for more accurate diagnosis and treatment.


Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 555
Author(s):  
Monica Miranda Mugica ◽  
Kay Louise McGuinness ◽  
Nathan Scott Lawrence

This work summarizes the electrochemical response of a salicylic acid-based carbon electrode for use as a novel solid-state reference electrode in a redox-based pH sensor. This novel reference produces a pH insensitive response over a range of pH 3–10 in solutions with low buffer concentrations, different compositions, conductivities, and ionic strengths is produced. The pH of the local environment is shown to be determined by the chemistry and the electrochemical response of the redox active species on the surface of the electrode; the local pH can be controlled by the electropolymerized salicylic acid moieties due to the acid concentration on the surface, avoiding any perturbation in environmental pH and leading to a stable novel reference system. Sensitivities of −7.1 mV/pH unit, −2.4 mV/pH unit, −0.2 mV/pH unit, and 2.5 mV/pH units were obtained for different food medias, hydroponic solution, seawater, and cell-culture media, respectively, confirming its ability to control the local pH of the electrode. This reference system is paired with a new pH sensing element based on electropolymerized flavanone to provide a calibration free, pH sensitive sensor to effectively and accurately measure the pH of various media with high viscosity, low conductivity, low/high buffer concentration or cell-culture environment, presenting a maximum error of +/−0.03 pH units.


Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 485
Author(s):  
Dominik Berndt ◽  
Josef Muggli ◽  
Robert Heckel ◽  
Mohd Fuad Rahiman ◽  
Matthias Lindner ◽  
...  

Gas concentration monitoring is essential in industrial or life science areas in order to address safety-relevant or process-related questions. Many of the sensors used in this context are based on the principle of thermal conductivity. The 3ω-method is a very accurate method to determine the thermal properties of materials. It has its origin in the thermal characterization of thin solid films. To date, there have been very few scientific investigations using this method to determine the thermal properties of gases and to apply it to gas measurement technology. In this article, we use two exemplary gases (H2 and CO2) for a systematical investigation of this method in the context of gas analysis. To perform our experiments, we use a robust, reliable sensing element that is already well established in vacuum measurement technology. This helix-shaped thin wire of tungsten exhibits high robustness against chemical and mechanical influences. Our setup features a compact measurement environment, where sensor operation and data acquisition are integrated into a single device. The experimental results show a good agreement with a simplified analytical model and FEM simulations. The sensor exhibits a lower detection limit of 0.62% in the case of CO2, and only 0.062% in case the of H2 at an excitation frequency of 1Hz. This is one of the lowest values reported in literature for thermal conductivity H2 sensors.


2022 ◽  
Vol 2 ◽  
Author(s):  
Federica Catania ◽  
Hugo De Souza Oliveira ◽  
Martina A. Costa Angeli ◽  
Manuela Ciocca ◽  
Salvador Pané ◽  
...  

Thin-film transistors (TFTs) based on amorphous indium-gallium-zinc-oxide (a-IGZO) have proved promising features for flexible and lightweight electronics. To achieve technological maturity for commercial and industrial applications, their stability under extreme environmental conditions is highly required. The combined effects of temperature (T) from −30.0°C to 50.0°C and relative humidity (RH) stress from 0 to 95% on a-IGZO TFT is presented. The TFT performances and the parameters variation were analysed in two different experiments. First, the TFT response was extracted while undergoing the most extreme climate conditions on Earth, ranging from the African Desert (50.0°C, 22%) to Antarctic (−30.0°C, 0%). Afterwards, the device functionality was demonstrated in three parts of the human body (forehand, arm and foot) at low (35%), medium (60%) and high (95%) relative humidity for on-skin and wearable applications. The sensitivity to T/RH variations suggests the suitability of these TFTs as sensing element for epidermal electronics and artificial skin.


Author(s):  
Chanakarn Sanguarnsak ◽  
Kiattisak Promsuwan ◽  
Jenjira Saichanapan ◽  
Asamee Soleh ◽  
Kasrin Saisahas ◽  
...  

Abstract A new electrode material of phosphorus-doped multi-walled carbon nanotubes (P-MWCNTs) was developed as an electrochemical sensing element for amitriptyline (AMT). P-MWCNTs were hydrothermally synthesized and drop casted on a glassy carbon electrode (P-MWCNTs/GCE). The P-MWCNTs were morphologically, chemically and structurally characterized. The electrochemical characteristics of the P-MWCNTs/GCE were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and adsorptive stripping voltammetry (AdSV). The P-MWCNTs increased electron transfer at the GCE and the electrochemical conductivity of the electrode. Electrocatalytic activity toward the oxidation of AMT was excellent. In the optimal voltammetric condition, the P-MWCNTs/GCE produced linear ranges of 0.50 to 10 µg mL-1 and 10 to 40 µg mL-1. The limit of detection (LOD) and limit of quantification (LOQ) were 0.15 µg mL-1 (0.54 µM) and 0.52 µg mL-1 (1.80 µM), respectively. The developed sensor displayed good repeatability, reproducibility and specificity. The sensor successfully quantified AMT in pharmaceutical tablets, giving results consistent with spectrophotometric analysis. The sensor achieved recoveries from 98±2% to 101±5% from spiked urine samples. The proposed sensor could be applied to determine AMT in pharmaceutical and urine samples for forensic toxicology.


2022 ◽  
Vol 2 ◽  
Author(s):  
Yanyan Fan ◽  
Hongbin Zhao ◽  
Yifan Yang ◽  
Yi Yang ◽  
Tianling Ren ◽  
...  

Graphene-based stretchable and flexible strain sensors are one of the promising “bridges” to the biomedical realm. However, enhancing graphene-based wearable strain sensors to meet the demand of high sensitivity, broad sensing range, and recoverable structure deformation simultaneously is still a great challenge. In this work, through structural design, we fabricated a simple Ecoflex/Overlapping Graphene/Ecoflex (EOGE) strain sensor by encapsulating a graphene sensing element on polymer Ecoflex substrates using a drop-casting method. The EOGE strain sensor can detect stretching with high sensitivity, a maximum gauge factor of 715 with a wide strain range up to 57%, and adequate reliability and stability over 1,000 cycles for stretching. Moreover, the EOGE strain sensor shows recoverable structure deformation, and the sensor has a steady response in the frequency disturbance test. The good property of the strain sensor is attributed to the resistance variation induced by the overlap and crack structure of graphene by structural design. The vibrations caused by sound and various body movements have been thoroughly detected, which exhibited that the EOGE strain sensor is a promising candidate for wearable biomedical electronic applications.


2022 ◽  
Vol 1215 (1) ◽  
pp. 012010
Author(s):  
A.V. Styazhkina ◽  
A.A. Belogurov ◽  
Ya.V. Belyaev ◽  
A.T. Tulaev

Abstract Development of micromechanical inertial sensors have made it possible to use them in the navigation and motion control systems. This application area imposes strict requirements on sensors. One of the ways to meet the requirements and to improve the gyroscope characteristics is to apply a dual- or multi-mass architecture of a gyroscope sensing element. This paper presents the results of dual-mass micromechanical gyroscope with a measurement range of ±450°/s design. The complex design method, including simulation at the system level, model refinement based on the results of finite element modelling, and modelling of individual electronic blocks at the circuit level, is described.


2022 ◽  
Vol 355 ◽  
pp. 01026
Author(s):  
Sikang Cai ◽  
Guicong Wang ◽  
Yingjun Li ◽  
Xiaoqi Yang

The high-frequency dynamic piezoelectric pressure sensor has the advantages of simple structure, long service life, high natural frequency, excellent signal-to-noise ratio and great sensitivity. It is appropriate for measuring high dynamic, dynamic or quasi-static pressure changes and pressure fluctuations. And this kind of sensor is widely utilized in the shock wave testing. The force-sensitive element is one of the main factors affecting the static and dynamic performance of piezoelectric pressure sensors. Basing on the piezoelectric equation and coupling effect between mechanics and electricity, in this paper, the finite element model of the high-frequency dynamic piezoelectric pressure sensor is established. The influences of the force-sensing element on the sensitivity of the sensor are analysed. Referential suggestions for choosing force-sensitive element of high-frequency dynamic piezoelectric pressure sensor are provided.


Author(s):  
Shang-Lin Yeh ◽  
Piyush Deval ◽  
Jhih-Guang Wu ◽  
Shyh-Chyang Luo ◽  
Wei-Bor Tsai

Electrochemical techniques are highly sensitive and label-free sensing methods for the detection of various biomarkers, toxins, or pathogens. An ideal sensing element should be electroconductive, nonfouling, and readily available for...


ACTA IMEKO ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 162
Author(s):  
Gianluca Caposciutti ◽  
Bernardo Tellini ◽  
Alfredo Cigada ◽  
Stefano Manzoni

New low-cost measuring devices require that the box housing and electronics have the cost aligned with the sensing system. Nowadays, metallic clips and/or glue are commonly used to fix the electronics to the box, thus providing the same motion of the structure to the sensing element. However, these systems may undergo daily or seasonal thermal cycles, and the combined effect of thermal and mechanical stress can determine significant uncertainties in the measurand evaluation. To study these effects, we prepared some parallel plates capacitors by using glue as a dielectric material. We used different types of fixing and sample assembly to separate the effects of glue softening on the capacitor active area and plates distance. Therefore, we assessed the sample modification by measuring the capacitance variation during controlled temperature cycles. We explored possible non-linear behaviour of the capacitance vs. temperature, and possible effects of thermal cycles on the glue geometry. Further work is still needed to properly assess the nature of this phenomenon and to study the effect of mechanical stress on the sample’s capacitance.


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