scholarly journals The Effect of Humidity on the Electrical Resistance of Smart Sensor Based on Carbon Fibers

2019 ◽  
Author(s):  
Marcin Górski ◽  
Rafał Krzywoń ◽  
Sofija Kekez
Keyword(s):  
Carbon Fibers ◽  
Electrical Resistance ◽  
Bridge Circuit ◽  
High Sensitivity ◽  
Wheatstone Bridge ◽  
Smart Sensor ◽  
Building Structures ◽  
Humidity Resistance ◽  
Externally Bonded ◽  
Textile Sensor

The paper describes preliminary studies on the influence of humidity on the electrical resistance of a textile sensor made of carbon fibers. The concept of the sensor refers to externally bonded fiber reinforcement commonly used to strengthen building structures. However, the zig-zag arrangement of carbon fiber tow allows measuring strains, as it is done in popular resistive strain gauges. The sensor tests proved its effectiveness in the measurement of strains, but also showed a high sensitivity to changes in the temperature and humidity which unfavorably affects the readings and their interpretation. The influence of these factors must be compensated. Due to the size of the sensor, there is not possible electrical compensation by the combining of several sensors into the half or full Wheatstone bridge circuit. Only mathematical compensation based on known humidity resistance functions is possible. The described research is the first step to develop such relations. The tests were carried out at temperatures of 10 °C, 20 °C and 30 °C, with changing the humidity in the range of 30-90%.

scholarly journals Self-Monitoring Strengthening System Based on Carbon Fiber Laminate

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Rafal Krzywon ◽  
Marcin Gorski ◽  
Szymon Dawczynski ◽  
Leszek Szojda ◽  
Joao Castro Gomes ◽  
...  
Keyword(s):  
Carbon Fibers ◽  
Measurement Techniques ◽  
High Strength ◽  
Building Structures ◽  
Electrical Conductor ◽  
Self Monitoring ◽  
Carbon Fiber Laminate ◽  
Externally Bonded ◽  
Acrylic Fibers

Externally bonded composites reinforced with high-strength fibers are increasingly popular in construction, especially in structures’ strengthening, where the best possible mechanical properties are required. At the same time the ability to autodetect threats is one of the most desirable features of contemporary structures. The authors of the paper have developed an intelligent fabric, wherein the carbon fibers play the role of not only tensile reinforcement but also strain sensor. The idea is based on the construction of the strain gauge, where the thread of carbon fibers arranged in zig-zag pattern works as electrical conductor and is insulated by parallel thread of glass or acrylic fibers. Preliminary laboratory tests were designed to create effective measurement techniques and assess the effectiveness of the strengthening of selected building structures, as reinforced concrete and timber beams. Presented in the paper, selected results of these studies are very promising, although there were some noted problems to be considered in next steps. The main problem here is the control of the cross section of the fibers tow, affecting the total resistance of the fabric. One of the main deficiencies of the proposed solution is also sensitivity to moisture.

Activity response to oxygen in the brook trout, Salvelinus fontinalis (Mitchill)

1970 ◽  
Vol 48 (5) ◽  
pp. 1067-1072 ◽  
Author(s):  
J. W. T. Dandy
Keyword(s):  
Brook Trout ◽  
Bridge Circuit ◽  
Flow System ◽  
Wheatstone Bridge ◽  
Threshold Concentration ◽  
Response Threshold ◽  
Locomotory Activity ◽  
Absolute Concentration ◽  
Activity Response ◽  
Voltage Output

Locomotory activity of brook trout was measured at 10 °C in water of three different oxygen concentrations. Activity was sensed with a thermistor probe in a Wheatstone bridge circuit. Voltage output of the bridge was integrated automatically and recorded.Exposure to 6.0 and 1.7 p.p.m. oxygen induced tin activity response within minutes which reached a peak during the first hour then slowly waned. The intensity of response was greater to lower than to higher oxygen levels. Not all fish responded to 8.0 p.p.m. The response threshold concentration was estimated to be 8.3 p.p.m. oxygen. The response appeared to be made to the absolute concentration rather than to the rate of oxygen decrease.Various difficulties in estimating thresholds for dissolved substances in a constant flow system are considered. It is suggested that the response threshold found here be applied only in the specific circumstances of this experiment.

2. On the Measurement of Resistance to Electrolytes

1884 ◽  
Vol 12 ◽  
pp. 178-181
Author(s):  
Cargill G. Knott
Keyword(s):  
Rapid Growth ◽  
Electrical Resistance ◽  
Wheatstone Bridge ◽  
Bridge Method

The difficulties attending the measurement of the electrical resistance of electrolytes are well known, the rapid growth of the polarisation of the electrodes especially preventing the application of the ordinary Wheatstone Bridge method. The polarisation may be kept down by using alternating currents, as was done by Kohlrausch; and this method is no doubt the most general and most accurate which has yet been applied.

scholarly journals Development of Self-Sensing Textile Strengthening System Based on High-Strength Carbon Fiber

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2062
Author(s):  
Marcin Górski ◽  
Rafał Krzywoń ◽  
Magdalena Borodeńko
Keyword(s):  
Carbon Fiber ◽  
Carbon Fibers ◽  
High Efficiency ◽  
High Strength ◽  
Strain Gauges ◽  
Building Structures ◽  
Climatic Chamber ◽  
Daily Cycle ◽  
Temperature Changes ◽  
Temperature And Humidity

The monitoring of structures is one of the most difficult challenges of engineering in the 21st century. As a result of changes in conditions of use, as well as design errors, many building structures require strengthening. This article presents research on the development of an externally strengthening carbon-fiber textile with a self-sensing option, which is an idea is based on the pattern of resistive strain gauges, where thread is presented in the form of zig-zagging parallel lines. The first laboratory tests showed the system’s high efficiency in the measurement of strains, but also revealed its sensitivity to environmental conditions. This article also presents studies on the influence of temperature and humidity on the measurement, and to separate the two effects, resistance changes were tested on unloaded concrete and wooden samples. The models were then placed in a climatic chamber, and the daily cycle of temperature and humidity changes was simulated. The research results confirmed preliminary observations of resistivity growths along with temperature. This effect is more visible on concrete samples, presumably due to its greater amount of natural humidity. The strain measurement with carbon fibers is very sensitive to temperature changes, and applications of this method in practice require compensation.

scholarly journals Pressure Sensor with New Electrical Circuit Utilizing Bipolar Junction Transistor

2021 ◽  
Author(s):  
Mikhail
Keyword(s):  
Theoretical Model ◽  
Pressure Sensor ◽  
High Sensitivity ◽  
Wheatstone Bridge ◽  
Electrical Circuit ◽  
Sensor Chip ◽  
Chip Size ◽  
Junction Transistor ◽  
Developed Pressure ◽  
P Type

High sensitivity MEMS pressure sensor chip for different ranges (1 to 60 kPa) utilizing the novel electrical circuit of piezosensitive differential amplifier with negative feedback loop (PDA-NFL) is developed. Pressure sensor chip PDA-NFL utilizes two bipolar-junction transistors (BJT) with vertical n-p-n type structure (V-NPN) and eight piezoresistors (p-type). Both theoretical model of sensor response to pressure and temperature and experimental data are presented. Data confirms the applicability of theoretical model. Introduction of the amplifier allows for decreasing chip size while keeping the same sensitivity as a chip with classic Wheatstone bridge circuit.

scholarly journals Multifunctional Textile Platform for Fiber Optic Wearable Temperature-Monitoring Application

Micromachines ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 866 ◽  
Author(s):  
Ziyang Xiang ◽  
Liuwei Wan ◽  
Zidan Gong ◽  
Zhuxin Zhou ◽  
Zhengyi Ma ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Temperature Sensor ◽  
High Sensitivity ◽  
Wavelength Shift ◽  
Heat Sources ◽  
Time Dynamic ◽  
Textile Sensor ◽  
Fbg Sensors ◽  
Comfort Parameters ◽  
Monitoring Application

Wearable sensing technologies have been developed rapidly in the last decades for physiological and biomechanical signal monitoring. Much attention has been paid to functions of wearable applications, but comfort parameters have been overlooked. This research presents a developed fabric temperature sensor by adopting fiber Bragg grating (FBG) sensors and processing via a textile platform. This FBG-based quasi-distributed sensing system demonstrated a sensitivity of 10.61 ± 0.08 pm/°C with high stability in various temperature environments. No obvious wavelength shift occurred under the curvatures varying from 0 to 50.48 m−1 and in different integration methods with textiles. The temperature distribution monitored by the developed textile sensor in a complex environment with multiple heat sources was deduced using MATLAB to present a real-time dynamic temperature distribution in the wearing environment. This novel fabric temperature sensor shows high sensitivity, stability, and usability with comfort textile properties that are of great potential in wearable applications.

scholarly journals High-sensitivity tunneling magneto-resistive micro-gyroscope with immunity to external magnetic interference

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Li Jin ◽  
Shi-Yang Qin ◽  
Rui Zhang ◽  
Meng-Wei Li
Keyword(s):  
Bridge Circuit ◽  
High Sensitivity ◽  
Micro Electro Mechanical System ◽  
Detection Sensitivity ◽  
Force Detection ◽  
Mems Gyroscope ◽  
Mems Gyroscopes ◽  
Potential Applications ◽  
Magneto Resistance ◽  
Total Sensitivity

Abstract Micro-electro-mechanical system (MEMS) gyroscopes have numerous potential applications including guidance, robotics, tactical-grade navigation, and automotive applications fields. The methods with ability of the weak Coriolis force detection are critical for MEMS gyroscopes. In this paper, we presented a design of MEMS gyroscope based on the tunneling magneto-resistance effect with higher detection sensitivity. Of all these designed parameters, the structural, magnetic field, and magneto-resistance sensitivity values reach to 21.6 nm/°/s, 0.0023 Oe/nm, and 29.5 mV/Oe, thus, with total sensitivity of 1.47 mV/°/s. Multi-bridge circuit method is employed to suppress external magnetic interference and avoid the integration error of the TMR devices effectively. The proposed tunneling magneto-resistive micro-gyroscope shows a possibility to make an inertial grade MEMS gyroscope in the future.

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