Effect of Additive Manufacturing on β‐Phase Poly(Vinylidene Fluoride)‐Based Capacitive Temperature Sensors

Abstract

Additive manufacturing, commonly known as 3D printing, significantly simplifies the manufacturing process for soft electronics. This work demonstrates the feasibility of a fully 3D-printed flexible poly(vinylidene fluoride) (PVdF) capacitive temperature sensor. The sensor is constructed using fused deposition modeling (FDM)-printed PVdF film as the dielectric (thickness ≈180–280 μm) sandwiched between two parallel Direct Ink Writing (DIW) printed silver electrodes (entire device thickness ≈200–380 μm). The motion of the nozzle can facilitate mechanical drawing to the molten PVdF filament, which is a necessary condition to increase the β-phase content (critical for the sensitivity of the sensor). With optimized printing parameters, the highest β-phase content (21.30%) is achieved when printing with a nozzle temperature of 200 °C and a print speed of 70 mm s−1. The research demonstrates the application of the device as a temperature sensor by applying heating-and-cooling cycles from room temperature (25 °C) up to 140 °C while measuring the capacitance as a function of frequency under different temperatures. The sensor exhibits a stable sensitivity of 3 pF °C−1 at 102 Hz and higher frequencies and improved sensitivities at frequencies higher than 102 Hz after dielectric polarization via the corona poling method.