posted on 2024-02-03, 14:05authored byZhikang Li, Kang Zhao, Jiaxiang Wang, Bin Wang, Jijian Lu, Boqing Jia, Tian Ji, Xiangguang Han, Guoxi Luo, Yilin Yu, Lu Wang, Min Li, Zhengjin Wang, Libo Zhao
Flexible capacitive tactile sensors show great promise
in personalized
healthcare monitoring and human–machine interfaces, but their
practical application is normally hindered because they rarely possess
the required comprehensive performance, that is, high pressure sensitivity
and fast response within a broad pressure range, high structure robustness,
performance consistency, etc. This paper aims to engineer flexible
capacitive pressure sensors with highly ordered porous dielectric
microstructures and a 3D-printing-based fully solution-processable
fabrication process. The proposed dielectric layer with uniformly
distributed interior microporous can not only increase its compressibility
and dynamic response within an extended pressure range but also enlarge
its contact area with electrodes, contributing to a simultaneous improvement
in the sensitivity, response speed, detection range, and structure
robustness. Meanwhile, owing to its superior abilities in complex
structure manufacturing and dimension controlling, the proposed 3D-printing-based
fabrication process enables the consistent fabrication of the porous
microstructure and thus guarantees device consistency. As a result,
the prepared pressure sensors exhibit a high sensitivity of 0.21 kPa–1, fast response and relaxation times of 112 and 152
ms, an interface bonding strength of more than 455.2 kPa, and excellent
performance consistency (≤5.47% deviation among different batches
of sensors) and tunability. Encouraged by this, the pressure sensor
is further integrated with a wireless readout circuit and realizes
wireless wearable monitoring of various biosignals (pulse waves and
heart rate) and body movements (from slight finger touch to large
knee bending). Finally, the influence law of the feature parameters
of the porous microstructure on device performance is established
by the finite element method, paving the way for sensor optimization.
This study motivates the development of flexible capacitive pressure
sensors toward practical application.