Carbon-laden foam makes super-sensitive pressure sensor: Page 2 of 2

April 10, 2019 //By Julien Happich
Carbon-laden foam makes super-sensitive pressure sensor
Using very simple process steps and cheap materials, a team of French researchers from the CNRS has devised thin capacitive sensors out of a carbon-laden elastomeric foam with exceptional pressure sensitivity.

What’s more, the high capacitance (over 100pF) can easily be measured with low-cost electronics, without any signal amplification. It only takes a 1V bias to record the device’s capacitive responses, and because the material’s resistivity is high, the sensor draws only about 100nW at 1 kPa of pressure sensing (then showing a resistance of 10MΩ). This is orders of magnitude more efficient than conventional silicon piezo-resistive pressure transducers, claim the researchers.

Taped to the patient’s wrist, the capacitive pressure sensor records pressure variations from the artery pulse, providing real-time and in-situ capacitive readings.

The authors anticipate that such ultrasensitive sensors could be designed as a simple patch to monitor blood-pressure by recording arterial pulse waves (as capacitive signals) and converting them into a pressure value using AI-based algorithms.

But such composite materials could also be used to design pressure sensitive artificial skins for robotics. One particular medical application mentioned in the paper is the use of robotics for the palpation of soft tissue organs, for the detection of embedded nodules in soft tissues. For millimetre-sized nodules, the variation of stiffness is below 0.1 kPa, the authors note, requiring highly sensitive sensors like the one they demonstrated.

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