Novel Application Fields of High-Voltage Electrostatic Flocking: Sensors (Part II) and (Part III)

Sensors (Part 2) — Pressure Sensors
Inspired by human skin and hair, electrostatic flocking technology has been applied in the fabrication of pressure sensors. [41] Similar to airflow sensors, when the fibers are subjected to pressure, conductive pathways form between the electrodes, resulting in changes in conductivity or resistance (Figure c). The vertical fiber surface formed by combining electrostatic flocking technology with silk exhibits high elasticity and sensitivity. This approach not only enables efficient mass production of sensors but also delivers outstanding performance—maintaining excellent responsiveness across a linear range (up to 2000 kPa) while achieving high sensitivity of 0.0285 kPa⁻¹. [41] Figure d displays dynamic response curves of the sensor under seven different pressure values ranging from 5 to 1500 kPa applied to the conductive material. [41] These results fully validate the sensor's sensitivity, operating pressure range, and consistency in electrical signal transmission.

Sensors (Part 3) — Self-Powered Sensors
Electrostatic flocking technology significantly enhances the charge transfer efficiency of triboelectric nanogenerators (TENGs) by dramatically increasing the surface area of the friction layers. [38] Inspired by the fish lateral line system and the gel-covered hair cells in neuromasts, Ma’s team developed an innovative fiber-based TENG device. This structure ingeniously integrates materials such as latex balloons, porous silicone rubber, nylon flock fibers, and silver-coated nylon yarn (Figure e). [38] When external force is applied, the contact area between the nylon flock and the silicone rubber increases, creating a potential difference that drives electrons to flow through the silver-coated nylon yarn to the ground, thereby generating an electric current (Figure f). [38] Leveraging the synergistic effect between the nylon flock and the porous silicone rubber, this fiber-based self-powered sensor demonstrates strong current output capability and high sensitivity to subtle mechanical displacements. This technology can contribute to the development of wearable systems for real-time respiratory monitoring and human-machine interaction. [38]

a) Manufacturing process diagram of the SCFN airflow sensor. Reprinted with permission. [13] Copyright ©2022 Wiley-VCH GmbH.
b) Two sets of cyclic sensing curves of the sensor under different airflow speeds. Reprinted with permission. [14] Copyright ©2022 Royal Society of Chemistry.
c) Working mechanism of the electrostatic flocking pressure sensor. Reprinted with permission. [41] Copyright ©2024 American Chemical Society.
d) Relative resistance change curves of the sensor under pressure applied to the conductive material. Reprinted with permission. [41] Copyright ©2024 American Chemical Society.
e) Schematic diagram of the FLLF-TENG structure. Reprinted with permission. [38] Copyright ©2024 The Author(s).
f) Microstructural analysis of the FLLF-TENG in原始状态 and compressed states. Reprinted with permission. [38] Copyright ©2024 The Author(s).

References
[38] G. Ma, M. Zhang, F. Gao, Y. Wang, L. Pu, Y. Song, J. She, D. Wang, B. Yu, K. Ba, Z. Han, L. Ren, Device 2024.
[41] A. Walter, A. Bernhardt, W. Pompe, M. Glinzky, B. Morozhik, G. Hoffmann, C. Cherif, H. Bertrand, W. Richter, G. Schmauch, J. Res. 2007, *77*.