Capacitive sensor measurement rate improves by pre-stretching

Porte, Elze; Sipple, Thomas; Botero, Lina Sanchez; Shah, Dylan; Kramer‐Bottiglio, Rebecca

doi:10.1109/robosoft51838.2021.9479328

Cited by 2 publications

(4 citation statements)

References 33 publications

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“…S7 ), which is in line with observations on other conductive polymers, although at temperatures above 0°C. 15 A high electrode resistance can affect the maximum measurement range of elastomer capacitance sensors, 52 , 53 and the increasing resistance with temperature explains the reduced performance of the sensors. The breakdown voltage of dielectric elastomers is also temperature dependent, 54 but this is unlikely to affect the sensor performance since these breakdown voltages are of a different order of magnitude (kV) compared with the voltages that are relevant to capacitive sensors (several V).…”

Section: Resultsmentioning

confidence: 99%

Characterization of Temperature and Humidity Dependence in Soft Elastomer Behavior

Porte,

Eristoff,

Agrawala

et al. 2024

Soft Robotics

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Soft robots are predicted to operate well in unstructured environments due to their resilience to impacts, embodied intelligence, and potential ability to adapt to uncertain circumstances. Soft robots are of further interest for space and extraterrestrial missions, owing to their lightweight and compressible construction. Most soft robots in the literature to-date are made of elastomer bodies. However, limited data are available on the material characteristics of commonly used elastomers in extreme environments. In this study, we characterize four commonly used elastomers in the soft robotics literature—EcoFlex 00-30, Dragon Skin 10, Smooth-Sil 950, and Sylgard 184—in a temperature range of −40°C to 80°C and humidity range of 5–95% RH. We perform pull-to-failure, stiffness, and stress-relaxation tests. Furthermore, we perform a case study on soft elastomers used in stretchable capacitive sensors to evaluate the implications of the constituent material behavior on component performance. We find that all elastomers show temperature-dependent behavior, with typical stiffening of the material and a lower strain at failure with increasing temperature. The stress-relaxation response to temperature depends on the type of elastomer. Limited material effects are observed in response to different humidity conditions. The mechanical properties of the capacitive sensors are only dependent on temperature, but the measured capacitance shows changes related to both humidity and temperature changes, indicating that component-specific properties need to be considered in tandem with the mechanical design. This study provides essential insights into elastomer behavior for the design and successful operation of soft robots in varied environmental conditions.

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Section: Resultsmentioning

confidence: 99%

Characterization of Temperature and Humidity Dependence in Soft Elastomer Behavior

Porte,

Eristoff,

Agrawala

et al. 2024

Soft Robotics

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show abstract

“…Dynamic electromechanical characterization of the sensors was carried out through 5000 cycles of straining up to 60% using a custom‐built cyclic tester, as described by Porte and co‐authors. [ 36 ] For cyclic testing, representative data from one sensor was selected for each dielectric material and sensor configuration.…”

Section: Methodsmentioning

confidence: 99%

“…Although there are many capacitive strain sensors in existing literature, [29,33,34] including previous works from our lab, [35][36][37] there remain several key ongoing challenges in the field regarding breathability, maximum measurement frequency, and sensor-garment integration. Here, we present a wearable capacitive sensor that addresses these identified limitations.…”

Section: Doi: 101002/admt202300378mentioning

confidence: 99%

“…Second, prior work has established that electrode resistance can affect the maximum frequency at which capacitance can be accurately measured, with characteristic frequencies around 5 kHz. [ 36 ] In this work, we demonstrate stable capacitance measurements up to 1 MHz, such that our sensor data can be easily read using standard Arduino hardware. The fidelity of the sensor response at high frequencies indicates its suitability for broader translation into soft robotics applications.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Stretchable, Breathable, and Washable Fabric Sensor for Human Motion Monitoring

Sánchez-Botero

Agrawala

Kramer‐Bottiglio

2023

Adv Materials Technologies

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Wearable strain sensors for movement tracking are a promising paradigm to improve clinical care for patients with neurological or musculoskeletal conditions, with further applicability to athletic wear, virtual reality, and next‐generation game controllers. Clothing‐like wearable strain sensors can support these use cases, as the fabrics used for clothing are generally lightweight and breathable, and interface with the skin in a manner that is mechanically and thermally familiar. Herein, a fabric capacitive strain sensor is presented and integrated into everyday clothing to measure human motions. The sensor is made of thin layers of breathable fabrics and exhibits high strains (>90%), excellent cyclic stability (>5000 cycles), and high water vapor transmission rates (≈50 g/h m2), the latter of which allows for sweat evaporation, an essential parameter of comfort. The sensor's functionality is verified under conditions similar to those experienced on the surface of the human body (35°C and % relative humidity) and after washing with fabric detergent. In addition, the fabric sensor shows stable capacitance at excitation frequencies up to 1 MHz, facilitating its low‐cost implementation in the Arduino environment. Finally, as a proof of concept, multiple fabric sensors are seamlessly integrated with commercial activewear to collect movement data. With the prioritization of breathability (air permeability and water vapor transmission), the fabric sensor design presented herein paves the way for future comfortable, unobtrusive, and discrete sensory clothing.

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Capacitive sensor measurement rate improves by pre-stretching

Cited by 2 publications

References 33 publications

Characterization of Temperature and Humidity Dependence in Soft Elastomer Behavior

Characterization of Temperature and Humidity Dependence in Soft Elastomer Behavior

Stretchable, Breathable, and Washable Fabric Sensor for Human Motion Monitoring

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