A Flexible Pressure Sensor With Sandwiched Carpets of Vertically Aligned Carbon Nanotubes Partially Embedded in Polydimethylsiloxane Substrates
Runzhi Zhang, Anthony Palumbo, Grzegorz Hader, Kang Yan, Jason Chang, Hongjun Wang, Eui‐Hyeok Yang
Abstract
This paper presents a flexible pressure sensor composed of two face-to-face electrodes of vertically aligned carbon nanotubes (VACNTs) carpets partially embedded in polydimethylsiloxane(PDMS) substrates. VACNTs were grown using atmospheric pressure chemical vapor deposition (APCVD) on a Si/SiO2 substrate and transferred onto PDMS for partial embedment. This unique synthesis permitted a rapid and facile integration of a flexible and stretchable platform for the pressure sensor. The change of resistance occurs due to the external pressure applied orthogonal to the surface. The substrate was stretched to 180% and bent at bending radii of 87 mm and 105 mm. The pressure sensor exhibited the response times of 40 ms during loading and 60 ms during unloading. As a proof-of-concept, the sensor was attached on human skin; the heart rate, muscle flexing, and walking signals of an individual have been measured. In respect to durability, this sensor also showed a stable performance for 10,000 loading/unloading cycles with a resistance retention of 82% demonstrating its long-term use for repeated cycles toward practical applications.