Pressure sensing is highly demanding in wearable devices,
robotics,
and artificial intelligence, whereas it is still a big challenge to
develop a pressure sensor with an excellent linear response in a broad
detection range. Herein, a flexible and porous carbon nanotube (CNT)/carbon
black (CB)/carbonyl iron powder (CIP)/silicone composite is proposed
by a simple strategy of mixing, curing, and washing. Due to the porous
structure induced by the sacrifice of sugar particles, an excellent
linear response (R
2 = 0.999) is achieved
for the composite sensor by manipulating the contributions of contact
resistance and tunnel resistance to the sensing performance via the
alternation of CB and CNT contents. Moreover, the porous structure
donates the composite sensor a low compressive modulus at a low pressure
level, while the CIPs introduced lead to a high compressive modulus
at a high pressure level with the assistance of an external magnetic
field. As a result, the sensor produced has a wide linear response
range of 80 Pa to 220 kPa, much wider than most of the linear response
pressure sensors reported previously. The wide detection range is
demonstrated by cyclic pressure tests in the frequency range of 0.1–5
Hz, durability tests, and monitoring human or robot motions including
breathing, walking, lifting, and boxing, etc. Taking the advantages
of low cost, high sensitivity, and excellent linear response in a
wide pressure range, the current composite sensor is promising for
precise monitoring of human motions and delicate controlling of robots.
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