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

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 approximate to 180-280 mu m) sandwiched between two parallel Direct Ink Writing (DIW) printed silver electrodes (entire device thickness approximate to 200-380 mu m). The motion of the nozzle can facilitate mechanical drawing to the molten PVdF filament, which is a necessary condition to increase the beta-phase content (critical for the sensitivity of the sensor). With optimized printing parameters, the highest beta-phase content (21.30%) is achieved when printing with a nozzle temperature of 200 degrees 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 degrees C) up to 140 degrees C while measuring the capacitance as a function of frequency under different temperatures. The sensor exhibits a stable sensitivity of 3 pF degrees C-1 at 10(2) Hz and higher frequencies and improved sensitivities at frequencies higher than 10(2) Hz after dielectric polarization via the corona poling method.

Automated summary

This study demonstrates the feasibility of a fully 3D-printed flexible temperature sensor using additive manufacturing. The sensor exhibits high sensitivity and stability in temperature measurement, and the printing parameters greatly affect the performance of the sensor. Dielectric polarization through the corona poling method improves the sensitivity at higher frequencies.