Low‐Cost, Highly Sensitive, and Flexible Piezoresistive Pressure Sensor Characterized by Low‐Temperature Interfacial Polymerization of Polypyrrole on Latex Sponge

Abstract

Piezoresistive pressure sensors based on sponge are widely concerned because of their wide strain range, convenient signal acquisition, and good compressibility, yet it is still a challenge to acquire sponge‐based pressure sensors with low cost and excellent sensing performance. Herein, low‐priced FeCl3.6H2O and pyrrole (Py) are dispersed in deionized water to form FeCl3.6H2O/Py solution. Commercial latex sponge is impregnated into this solution to prepare conductive polypyrrole/latex (PPy/latex) sponge through low‐temperature interfacial polymerization. The surface of latex sponge is covered by the micro‐wrinkled PPy, which endows the PPy/latex sponge with a certain electrical conductivity. The specific porous structure and high elasticity of the latex sponge are the basic conditions for PPy/latex sponge excellent piezoresistive behaviors. PPy/latex sponge based piezoresistive pressure sensor shows high sensitivity (0.084 kPa−1 at below 3.12 kPa), wider sensing range (0–85.0%) and long durability over 3800 s (1800 cycles). At the same time, the ability of the PPy/latex sponge based piezoresistive pressure sensor to monitor human movement has been successfully evaluated in some application scenarios, such as bending fingers, grabbing objects, tiptoe rising, and crouching.

Flexible Sensors Based on Conductive Polymers

“…To lower the mechanical and electromechanical hysteresis of the fabric bases Sponge-based piezoresistive sensors have gained a lot of interest due to their 3D typical porous structure, good elasticity, and large thickness. Low-temperature interfacial polymerization of polypyrene film doped with FeCl 3 on a commercial latex sponge as the base material led to a cheap, pressure sensor able to detect human movements (grabbing objects and bending fingers, crouching and standing on tiptoes) [60]. Py monomers were inserted by diffusion into the porous PU elastomer substrates and were in situ polymerized to prepare a stretchable electric material with a thin layer of polypyrrole (PPy) strongly anchored on PU surfaces.…”

High‐Sensitivity, Long‐Durability, and Wearable Pressure Sensor Based on the Polypyrrole/Reduced Graphene Oxide/(Fabric–Sponge–Fabric) for Human Motion Monitoring

“…To evaluate performance of the PPy/rGO/FSF pressure sensor, we list some performance indicators of the pressure sensor based on the 3D structure reported in recent literatures. These sensors include sponges (such as poly(vinyl alcohol) (PVA)/H 2 SO 4 @thermoplastic polyurethane (TPU) sponge, rGO/TPU sponge, and PPy@Latex sponge), [38][39][40] fabrics (such as PPy/cotton fabric, and two-layer thiolated graphene(GSH)@polyester (PET) fabric), [41,42] and aerogel (such as poly(3,4-thylenedioxythiophene) (PEDOT): poly(styrenesulfonate) (PSS)/polyimide (PI) aerogel, and polyimide nanofiber (PINF)/2D transition metal carbides and nitrides(MXene) aerogel). [43,44] The comparison of recently reported piezoresistive pressure sensors with our work is listed in Table 1.…”

Development of High-Sensitivity Piezoresistive Sensors Based on Highly Breathable Spacer Fabric with TPU/PPy/PDA Coating

“…Commonly used conductive polymers include polypyrrole (PPy) [ 30 , 31 , 32 ], polythiophene [ 33 ], polyaniline [ 34 ], etc. Among these, polypyrrole (PPy) is a good candidate for the preparation of sensors due to its simple synthesis process, low cost, high oxidation resistance, high conductivity and specific capacitance values, and easy film formation [ 35 , 36 ]. Through in situ polymerization, PPy can form continuous coatings or thin films on a variety of materials.…”