3D-printing-assisted flexible pressure sensor with concentric circles patterns and high sensitivity for health monitoring

Abstract

In this study, the flexible pressure sensor is fabricated using polydimethylsiloxane (PDMS) with concentric circles pattern (CCP) through a fused deposition modeling (FDM)-type three-dimensional (3D) printer, and poly (3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS) as the active layer. Through layer-by-layer additive manufacturing, the CCP surface is generated from a thin cone model with rough surfaces by the FDM-type 3D printer. A novel compression method is employed to convert the cone shape to planar microstructure over glass transition temperature of polylactic acid (PLA) filament. To endow the CCP surface, PDMS is replicated by compressed PLA with conductivity and the PEDOT: PSS is coated by drop-casting. The size of CCPs are controlled by changing printing layer height (PLH), which is one of the 3D printing parameters. Sensitivity enhances as the PLH increases, and the pressure sensor with 0.16-mm PLH exhibits outstanding sensitivity (160 kPa− 1), corresponding linear pressure range (0-0.577 kPa) with good linearity of (R2 = 0.978), compared to other PLHs. This pressure sensor exhibited stable and repeatable operation under various pressures and durability under 4.7 kPa for 2000 cycles. Finally, various health signal motions such as wrist pulse signals, swallowing, and pronunciation of words were demonstrated as an application. These results support the simple fabrication of high sensitive, flexible pressure sensor for human health monitoring.