Flexible electronics combined with new materials and fabrication processes offer unique characteristics such as mechanical flexibility, thin-form factor, large area scaling feasibility, and ...adaptability to irregular surfaces. In this work, a smart electronic skin adopting the hybrid system-in-foil concept is designed to monitor the uniaxial bending of a robotic gripper. The newly designed smart skin contains an array of printed strain gauges, organic thin-film transistor (TFT) addressing circuits and a 20 μm ultra-thin silicon readout chip, all integrated on the same polymeric foil. The silver-ink printed strain gauges achieve a relative resistance sensitivity ΔR/R of 2% and a gauge factor of 2. In addition, the organic TFT multiplexer containing a three-stage shift register and analogue switches operate at a frequency of 100 Hz and a supply voltage of 3 V. The ultra-thin silicon chip provides the functions of system control, strain gauge readout, analogue-to-digital conversion and serial communication.
Vibrating wire strain gauges are often the preferred technology for measuring strain in driven piles. However, measuring the residual strain after pile driving is challenging to accomplish using ...vibrating wire gauges. The driving process can cause a shift in the no-load reading from a relaxation of locked-in manufacturing strains in the pile or relaxation of the gauge wire tension. Also, there are temperature effects from installing piles below ground. A test pile program was developed using driven steel H-piles instrumented with vibrating wire strain gauges. The piles were subjected to dynamic forces by striking against a steel plate in an attempt to relax the locked-in manufacturing strain prior to installation. The strain gauges and thermistors were connected to a data logger during pile driving to record strain and temperature changes following installation. It was observed that applying a dynamic impact to the piles prior to installation resulted in a shift of 0–5 με (microstrain). Temperature effects from installing the piles in cooler ground resulted in a shift of strain in excess of 60 με in some strain gauges. It is concluded that temperature-induced shifts to strain must be measured following pile driving to interpret residual stresses.
We demonstrate a fully flexible micromachined cantilever-based aptasensor for sensitive and specific sensing of Staphylococcus Enterotoxin B (SEB). The proposed flexible cantilever was fabricated ...using parylene-C as surface passivation layers and poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT:PSS) as strain gauge for characterization of resistance. A spring constant of prepared cantilever was measured to be 12 nN/μm together with a deflection sensitivity of 1.42×10 -3 /μm. With assembled 78-mer 5'-biotinylated aptamers on the sensing cantilever surface, the fully flexible aptasensor is capable of specific recognition SEB with a limit detection of 0.3 ng/mL. To evaluate the applicability of the proposed aptasensor, detections on raw milk spiked with SEB were implemented. The comparison indicates the prepared aptasensor could be qualified for SEB recognition in food contaminants detections, and the fully flexible cantilever-based sensors have tremendous potential for applications in food safety evaluation.
Resistance strain force sensors have been applied to monitor the strains in various parts and structures for industrial use. Here, we review the working principles, structural forms, and fabrication ...processes for resistance strain gauges. In particular, we focus on recent developments in resistance stress transfer for resistance strain force sensors and the creep effect due to sustained loads and/or temperature variations. Various error compensation methods to reduce the creep effect are analyzed to develop a metrology standard for resistance strain force sensors. Additionally, the current status of carbon nanotubes (CNTs), silicon carbide (SiC), gallium nitride (GaN), and other wide band gap semiconductors for a wide range of strain sensors are reviewed. The technical requirements and key issues of resistance strain force sensors for future applications are presented.
Here we report on the fabrication and characterization of a novel type of strain gauge based on percolative networks of 2D materials. The high sensitivity of the percolative carrier transport to ...strain induced morphology changes was exploited in strain sensors that can be produced from a wide variety of materials. Highly reliable and sensitive graphene-based thin film strain gauges were produced from solution processed graphene flakes by spray deposition. Control of the gauge sensitivity could be exerted through deposition-induced changes to the film morphology. This exceptional property was explained through modeling of the strain induced changes to the flake–flake overlap for different percolation networks. The ability to directly deposit strain gauges on complex-shaped and transparent surfaces was presented. The demonstrated scalable fabrication, superior sensitivity over conventional sensors, and unique properties of the described strain gauges have the potential to improve existing technology and open up new fields of applications for strain sensors.
Flexible and transparent pressure sensor arrays can find applications in many places such as touch panels, artificial skin, or human motion detection. However, conventional strain gauges are rigid ...and opaque and are not suitable for such applications. Graphene‐based percolative strain gauges can overcome these challenges but currently are still in the infancy of their development. In this work, the performance of graphene‐based percolative strain gauges is investigated and guidelines to improve the durability and sensitivity of graphene films as sensing elements are developed. It is found that the gauge factor depends on the initial resistance of the graphene film. For the same film resistance, it is found that graphene flake size and film morphology also play a role in determining the gauge factor. Increasing the flake–flake resistance through assembly of surfactant molecules between graphene flakes provides an additional route to enhance the gauge factor. Furthermore, encapsulating the percolative film in micrometer‐thin Poly(methyl methacrylate) does not disrupt the sensing process but significantly improves the sensor's durability. Finally, thus enhanced graphene strain gauges are integrated into flexible and transparent pressure sensor arrays that exhibit high reproducibility and sensitivity.
The performance of graphene‐based percolative strain gauges is investigated and guidelines to improve the durability and sensitivity of graphene films as sensing elements are developed. The enhanced graphene strain gauges are encapsulated in micrometer‐thin Poly(methyl methacrylate) (PMMA) and integrated into flexible and transparent pressure sensor arrays that exhibit high reproducibility and sensitivity.
•The amplitude of out-put signal reflects the torque and frequency reflects the rotational speed.•It solves the problem of power supply and signal output of sensitive elements on the shaft.•This ...sensing method cleverly uses the non-contact principle of capacitance.
Torque and rotational speed are important parameters to characterize the power of rotating parts for mechanical systems, so a rotational shaft’s torque and rotational speed sensing method and real-time signal processing are key technologies for mechanized equipment, such as vehicles, ships, etc. Hence an advanced torque and speed sensing technology and a data processing technology are very important for improving the performance of mechanical equipment. However, the power transmission device’s rotational shaft has a compact structure and narrow space, so it is difficult to install a signal transmission and power supply device of a sensor on the rotational shaft. To solve these difficult problems, this paper proposes a rotational shaft torque and rotational speed measurement method coupling resistance and capacitance. This method uses two resistance strain gauges and a capacitive grating, and the capacitive grating transmits signals in a non-contact coupling manner. The sensor on the rotational shaft needs no power supply and the signals are transmitted to a measurement circuit from a stationary sleeve, so this method essentially solves the difficult problems in signal transmission and power supply. Simulation and measurement experiments show that the resistance strain gauges obtain information and the capacitive grating sensor transfers information. The method coupling resistance and capacitance for realizing information sensing is feasible, which is suitable for measuring the torque and rotational speed of the rotational shaft of mechanical equipment in spite of the compact structure and narrow space.
In this paper, we propose a novel tactile sensor with a “fingerprint” design, named due to its spiral shape and dimensions of 3.80 mm × 3.80 mm. The sensor is duplicated in a four-by-four array ...containing 16 tactile sensors to form a “SkinCell” pad of approximately 45 mm by 29 mm. The SkinCell was fabricated using a custom-built microfabrication platform called the NeXus which contains additive deposition tools and several robotic systems. We used the NeXus’ six-degrees-of-freedom robotic platform with two different inkjet printers to deposit a conductive silver ink sensor electrode as well as the organic piezoresistive polymer PEDOT:PSS-Poly (3,4-ethylene dioxythiophene)-poly(styrene sulfonate) of our tactile sensor. Printing deposition profiles of 100-micron- and 250-micron-thick layers were measured using microscopy. The resulting structure was sintered in an oven and laminated. The lamination consisted of two different sensor sheets placed back-to-back to create a half-Wheatstone-bridge configuration, doubling the sensitivity and accomplishing temperature compensation. The resulting sensor array was then sandwiched between two layers of silicone elastomer that had protrusions and inner cavities to concentrate stresses and strains and increase the detection resolution. Furthermore, the tactile sensor was characterized under static and dynamic force loading. Over 180,000 cycles of indentation were conducted to establish its durability and repeatability. The results demonstrate that the SkinCell has an average spatial resolution of 0.827 mm, an average sensitivity of 0.328 mΩ/Ω/N, expressed as the change in resistance per force in Newtons, an average sensitivity of 1.795 µV/N at a loading pressure of 2.365 PSI, and a dynamic response time constant of 63 ms which make it suitable for both large area skins and fingertip human–robot interaction applications.
Design and verification of FBG strain gauge Wang, Zhinan; Hua, Shihai; Wang, Dajian ...
Journal of engineering (Stevenage, England),
December 2019, Letnik:
2019, Številka:
23
Journal Article
Recenzirano
Odprti dostop
Compared with the traditional electrical resistance strain gauge, the fibre Bragg grating (FBG) is a new material that can be used to produce the strain sensor, which has many advantages such as ...convenient installation, low temperature drifting, less signal interference and higher transmitted quality. In this study, FBG sensor system configuration, design principle, numerical simulation and loading tests for the FBG strain gauge are expatiated extensively. At the last, one-axial and three-axial strain gauges are produced and some conclusions have been put forward. So the FBG strain gauge can meet the precision of the structure monitoring and replace the traditional sensors.
Data gloves with strain gauges are a widely used technology to record hand kinematics. Several researchers have experienced problems when using data glove models to record distal interphalangeal ...(DIP) joints, mainly in relation to bad glove fitting. The aim of this work is to report the problems that arise when using one of these gloves (CyberGlove) and to determine an appropriate hand size to avoid these problems. First, static controlled postures of DIP joints and dynamic recordings while closing/opening the fist were taken using the data gloves on participants with different hand sizes, in order to establish the minimum hand length that does not pose recording problems. The minimum obtained hand length that allowed proper recording was 184 mm. Then, validation was performed, which consisted of recording the functional range of motion of the DIP joints in a sample of eight healthy participants with hand lengths longer than the minimum obtained one. These results were then compared to the results found in the literature. Although the glove fit properly, some problems remained: difficulty to record small flexion angles or a diminished touch sensitivity. Its usability would improve if two or three different glove sizes were commercially available.
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