Flexible PDMS-based triboelectric nanogenerator for instantaneous force sensing and human joint movement monitoring

Abstract

Flexible wearable sensors with excellent electric response and self-powered capability have become an appealing hotspot for personal healthcare and human-machine interfaces. Here, based on triboelectric nanogenerator (TENG), a flexible self-powered tactile sensor composed of micro-frustum-arrays-structured polydimethylsiloxane (PDMS) film/copper (Cu) electrodes, and poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) nanofibers has been demonstrated. The TENG-based self-powered tactile sensor can generate electrical signals through the contact-separation process of two triboelectric layers under external mechanical stimuli. Due to the uniform and controllable micro-frustum-arrays structure fabricated by micro-electro-mechanical system (MEMS) process and the P(VDF-TrFE) nanofibers fabricated by electrostatic spinning, the flexible PDMS-based sensor presents high sensitivity of 2.97 V kPa −1 , stability of 40,000 cycles (no significant decay), response time of 60 ms at 1 Hz, low detection pressure of a water drop (~4 Pa, 35 mg) and good linearity of 0.99231 in low pressure region. Since the PDMS film presents ultra-flexibility and excellent-biocompatibility, the sensor can be comfortably attached on human body. Furthermore, the tactile sensor can recognize various types of human body movements by the corresponding electrical signals. Therefore, the as-prepared TENGs are potential on the prospects of gesture detection, health assessment, human-machine interfaces and so on.

Design and engineering of high‐performance triboelectric nanogenerator for ubiquitous unattended devices

“…We have comprehensively reviewed the recent advances of the optimization strategies for improving the output performance of the triboelectric devices, including but not limited to theoretical simulation, 13,37,49,52 materials engineering, [56][57][58][59][60] device engineering, 89,162,[164][165][166] and power management strategies. 211,[213][214][215] TENG has been proved to be a powerful energy technology for harvesting low-frequency, irregular, and distributed mechanical energy that is widely used in micro/high power sources for small electronic devices and sensors, [223][224][225][226] self-powered unattended systems for monitoring vital signs, human motion or environmental conditions, 45,187,192,[231][232][233][234][235] blue energy harvesting, [236][237][238] and electrochemical processes, and so forth.…”

“…Studies show that the surface charge density could be effectively enhanced by constructing microscopic structures or engineering the functional groups on the surfaces of triboelectric materials. [56][57][58][59][60][61][62][63] To study the influence of microstructure morphology and adhesion force on the output performance of TENGs, Jin et al 64 used an interaction potential to represent the adhesive interactions and half-space Green's functions that describe the surface deformations between the polydimethylsiloxane (PDMS) surface with pyramid array structure and a rigid metal plate. The results indicated that the deformation of interfacial structures directly determines TENG's voltage-pressure relationship.…”

“…• Micropattern template: The prepatterned substrate (eg, Si wafer) with designed micro/nanostructures by photolithography can be used as the template for producing textured triboelectric surfaces. [56][57][58][59][60] For instance, Fan et al 56 developed a transparent and flexible TENG with various patterned PDMS and PET as the two triboelectric layers. Line, cube, and pyramid structures were patterned on the PDMS films using the micropatterned Si wafer templates ( Figure 3D).…”

Wearable triboelectric sensors for biomedical monitoring and human-machine interface

“…Because the separate surface area is linearly correlated to the bending angles, the amplitude of output voltage can directly reflect the bending state. This quantification based on amplitude has been adopted in many researches ( Alam et al., 2020 ; Han et al., 2019 ; Liu et al., 2020 ; Yu et al., 2019 ). As a demonstration, five such kind of sensors are attached on to the fingers to monitor the motion of each finger and different gestures.…”

A Voiceprint Recognition Sensor Based on a Fully 3D‐Printed Triboelectric Nanogenerator via a One‐Step Molding Route

“…Through the AFM imaging technique, we can find that the surface of the PDMS is very smooth, with a surface roughness of 5 μm, providing a good guarantee for the smooth progress of the experiment. By the coupling of triboelectrification and electrostatic induction between tribolayers and the electrode, the output voltage and current can reach 0.1 V and 0.26 nA, respectively, when the PDMS film is pressed, which are shown in Figure b,c. The remarkable output characteristic implies that the fabricated device can be treated as a self‐powered sensor.…”