Design, Manufacture and Testing of Capacitive Pressure Sensors for Low-Pressure  Measurement Ranges

In the fields of humanoid robots, soft robotics, and wearable electronics, the development of artificial skins entails pressure sensors that are low in modulus, high in sensitivity, and minimal in hysteresis. However, few sensors in the literature can meet all the three requirements, especially in the low pressure range (<10 kPa). This article presents a design for such pressure sensors. The bioinspired liquid-filled cell-type structural design endows the sensor with appropriate softness (Young’s modulus < 230 kPa) and high sensitivity (highest at 0.7 kPa−1) to compression forces below 0.65 N (6.8 kPa). The low-end detection limit is ~0.0012 N (13 Pa), only triple the mass of a bee. Minimal resistance hysteresis of the pressure sensor is 7.7%. The low hysteresis is attributed to the study on the carbon/silicone nanocomposite, which reveals the effect of heat treatment on its mechanical and electromechanical hysteresis. Pressure measurement range and sensitivity of the sensor can be tuned by changing the structure and strain gauge parameters. This concept of sensor design, when combined with microfluidics technology, is expected to enable soft, stretchable, and highly precise touch-sensitive artificial skins.

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Bent belt-beam gauge: Extending low-pressure measurement limits in a hot-cathode ionization vacuum gauge by combining multiple methods

Journal of Vacuum Science & Technology A Vacuum Surfaces and Films ◽

10.1116/1.3400233 ◽

2010 ◽

Vol 28 (3) ◽

pp. 486-494 ◽

Cited By ~ 2

Author(s):

Fumio Watanabe

Keyword(s):

Pressure Measurement ◽

Low Pressure ◽

Multiple Methods ◽

Vacuum Gauge

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Development Of PVDF Thick Film Interdigitated Capacitors For Pressure Measurement On Flexible Melinex Substrates

MRS Proceedings ◽

10.1557/proc-870-h2.4 ◽

2005 ◽

Vol 870 ◽

Cited By ~ 1

Author(s):

Arous Arshak ◽

Khalil Arshak ◽

Deirdre Morris ◽

Olga Korostynska ◽

Essa Jafer

Keyword(s):

Polymer Film ◽

Thick Film ◽

Pressure Measurement ◽

Pressure Sensors ◽

High Sensitivity ◽

Strain Gauges ◽

Interdigitated Electrodes ◽

Higher Sensitivity

AbstractIn this work, a PVDF thick film paste was deposited onto interdigitated electrodes to form a capacitor. Two different substrates, alumina and Melinex® were used. Capacitors, fabricated on alumina substrates were tested as strain gauges, and showed a high sensitivity with low hysteresis. Capacitors on Melinex® substrates were tested as pressure sensors by adhering them to planar and cylindrical surfaces and subjecting them to pressures up to 300 kPa. Their sensitivity and hysteresis during cycling were examined and compared. It was found that sensors on cylindrical surfaces showed a higher sensitivity, however the hysteresis was also increased. It is thought that this is due to instabilities in the polymer film, accentuated by stretching of the substrate.

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Low pressure measurement using a Bayard-Alpert gauge with magnetic field modulation

Vacuum ◽

10.1016/s0042-207x(69)80002-3 ◽

1969 ◽

Vol 19 (2) ◽

pp. 65-67

Author(s):

J Visser ◽

J.W.J. van Zeist

Keyword(s):

Magnetic Field ◽

Pressure Measurement ◽

Low Pressure ◽

Magnetic Field Modulation ◽

Field Modulation

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Capacitive micromachined ultrasonic transducer for ultra-low pressure measurement: Theoretical study

AIP Advances ◽

10.1063/1.4939217 ◽

2015 ◽

Vol 5 (12) ◽

pp. 127231 ◽

Cited By ~ 5

Author(s):

Zhikang Li ◽

Libo Zhao ◽

Zhuangde Jiang ◽

Sina Akhbari ◽

Jianjun Ding ◽

...

Keyword(s):

Pressure Measurement ◽

Theoretical Study ◽

Ultrasonic Transducer ◽

Low Pressure ◽

Capacitive Micromachined Ultrasonic Transducer

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Highly-Sensitive Textile Pressure Sensors Enabled by Suspended-Type All Carbon Nanotube Fiber Transistor Architecture

Micromachines ◽

10.3390/mi11121103 ◽

2020 ◽

Vol 11 (12) ◽

pp. 1103

Author(s):

Jae Sang Heo ◽

Keon Woo Lee ◽

Jun Ho Lee ◽

Seung Beom Shin ◽

Jeong Wan Jo ◽

...

Keyword(s):

Carbon Nanotube ◽

Pressure Sensor ◽

Pressure Range ◽

Pressure Sensors ◽

High Sensitivity ◽

Low Pressure ◽

Electronic Textiles ◽

Carbon Nanotube Fiber ◽

Cnt Fiber ◽

Walled Carbon Nanotubes

Among various wearable health-monitoring electronics, electronic textiles (e-textiles) have been considered as an appropriate alternative for a convenient self-diagnosis approach. However, for the realization of the wearable e-textiles capable of detecting subtle human physiological signals, the low-sensing performances still remain as a challenge. In this study, a fiber transistor-type ultra-sensitive pressure sensor (FTPS) with a new architecture that is thread-like suspended dry-spun carbon nanotube (CNT) fiber source (S)/drain (D) electrodes is proposed as the first proof of concept for the detection of very low-pressure stimuli. As a result, the pressure sensor shows an ultra-high sensitivity of ~3050 Pa−1 and a response/recovery time of 258/114 ms in the very low-pressure range of <300 Pa as the fiber transistor was operated in the linear region (VDS = −0.1 V). Also, it was observed that the pressure-sensing characteristics are highly dependent on the contact pressure between the top CNT fiber S/D electrodes and the single-walled carbon nanotubes (SWCNTs) channel layer due to the air-gap made by the suspended S/D electrode fibers on the channel layers of fiber transistors. Furthermore, due to their remarkable sensitivity in the low-pressure range, an acoustic wave that has a very tiny pressure could be detected using the FTPS.

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Flexible Ecoflex®/Graphene Nanoplatelet Foams for Highly Sensitive Low-Pressure Sensors

Sensors ◽

10.3390/s20164406 ◽

2020 ◽

Vol 20 (16) ◽

pp. 4406

Author(s):

Marco Fortunato ◽

Irene Bellagamba ◽

Alessio Tamburrano ◽

Maria Sabrina Sarto

Keyword(s):

High Performance ◽

Pressure Sensors ◽

High Sensitivity ◽

Cost Effective ◽

Low Pressure ◽

Human Motion ◽

Compression Tests ◽

Piezoresistive Sensors ◽

Human Motion Detection ◽

Pressure Regime

The high demand for multifunctional devices for smart clothing applications, human motion detection, soft robotics, and artificial electronic skins has encouraged researchers to develop new high-performance flexible sensors. In this work, we fabricated and tested new 3D squeezable Ecoflex® open cell foams loaded with different concentrations of graphene nanoplatelets (GNPs) in order to obtain lightweight, soft, and cost-effective piezoresistive sensors with high sensitivity in a low-pressure regime. We analyzed the morphology of the produced materials and characterized both the mechanical and piezoresistive response of samples through quasi-static cyclic compression tests. Results indicated that sensors infiltrated with 1 mg of ethanol/GNP solution with a GNP concentration of 3 mg/mL were more sensitive and stable compared to those infiltrated with the same amount of ethanol/GNP solution but with a lower GNP concentration. The electromechanical response of the sensors showed a negative piezoresistive behavior up to ~10 kPa and an opposite trend for the 10–40 kPa range. The sensors were particularly sensitive at very low deformations, thus obtaining a maximum sensitivity of 0.28 kPa−1 for pressures lower than 10 kPa.

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The Effect of Humidity on the Stability of LTCC Pressure Sensors

Metrology and Measurement Systems ◽

10.2478/v10178-012-0012-0 ◽

2012 ◽

Vol 19 (1) ◽

pp. 133-140 ◽

Cited By ~ 6

Author(s):

Marina Zarnik ◽

Darko Belavic

Keyword(s):

Pressure Sensors ◽

Low Pressure ◽

Numerical Analyses ◽

Capacitive Sensors ◽

Differential Mode ◽

Piezoresistive Sensors ◽

Mode Of Operation ◽

The Stability

The Effect of Humidity on the Stability of LTCC Pressure SensorsLTCC-based pressure sensors are promising candidates for wet-wet applications in which the effect of the surrounding media on the sensor's characteristics is of key importance. The effect of humidity on the sensor's stability can be a problem, particularly in the case of capacitive sensors. A differential mode of operation can be a good solution, but manufacturing the appropriate sensing capacitors remains a major challenge. In the case of piezoresistive sensors the influence of humidity is less critical, but it still should be considered as an important parameter when designing sensors for low-pressure ranges. In this paper we discuss the stability of the sensors' offset characteristics, which was inspected closely using experimental and numerical analyses.

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