Effects of Three-Dimensional Circular Truncated Cone Microstructures on the Performance of Flexible Pressure Sensors

Abstract

Three-dimensional microstructures play a key role in the fabrication of flexible electronic products. However, the development of flexible electronics is limited in further applications due to low positioning accuracy, the complex process, and low production efficiency. In this study, a novel method for fabricating three-dimensional circular truncated cone microstructures via low-frequency ultrasonic resonance printing is proposed. Simultaneously, to simplify the manufacturing process of flexible sensors, the microstructure and printed interdigital electrodes were fabricated into an integrated structure, and a flexible pressure sensor with microstructures was fabricated. Additionally, the effects of flexible pressure sensors with and without microstructures on performance were studied. The results show that the overall performance of the designed sensor with microstructures could be effectively improved by 69%. Moreover, the sensitivity of the flexible pressure sensor with microstructures was 0.042 kPa−1 in the working range of pressure from 2.5 to 10 kPa, and the sensitivity was as low as 0.013 kPa−1 within the pressure range of 10 to 30 kPa. Meanwhile, the sensor showed a fast response time, which was 112 ms. The stability remained good after the 100 cycles of testing. The performance was better than that of the flexible sensor fabricated by the traditional inverted mold method. This lays a foundation for the development of flexible electronic technology in the future.

Resonant printing flexible piezoresistive pressure sensor with spherical microstructures

“…Inverted template [50] 0.02 / 1-100 Inverted template [51] 0.0143 / 25-60 Inverted template [52] 0.831 30-60 0-0.5 Printing [53] 0.0069 / 0-100 Printing [49] 0.013 112 2.5-30 Printing in this work 0.024 72 1-100 in table 1. The sensor prepared by Zhang et al [42] had a high sensitivity and fast response, while, its working pressure and pressure range were smaller.…”

“…where S is the sensitivity of sensor, R is the output resistance of sensor when stimulated, R 0 is the initial resistance of sensor when not stimulated, ∆P is sensor pressure per unit area, ∆R and ρ R are the resistance change and resistance change rate, respectively, which mainly influences sensitivity. Based on our previous work [49], the sensitivity of the sensor with micro-structures could be improved by 133%. Figure 7(b) plots sensitivity of the manufactured FPP sensor, showing that the sensitivity reached 0.024 kPa −1 under working pressures between 1 kPa and 20 kPa.…”

A flexible piezoresistive pressure sensor comprising a microstructure printed with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) copolymers@graphene hybrid ink

“…11 At present, there are three main pressure sensor technologies on the market: capacitive, 12 piezoelectric, 13,14 and piezoresistive pressure sensors. 15,16 Piezoresistive sensors are most widely used because they are more sensitive and cheaper than the other types of sensors.…”