Advances in flexible piezoresistive pressure sensor

Abstract

In recent years, the flexible piezoresistive pressure sensor has attracted widespread attention due to the trend of improved wearable electronics applied to the field of electronic skin, disease diagnosis, motion detection and health monitoring. Here in this paper, the latest progress of the exploitation of flexible piezoresistive pressure sensors is reviewed in terms of sensing mechanism, selection of sensing materials, structural design and their advanced application. Firstly, the sensing mechanism of piezoresistive pressure sensors is generally introduced from the band structure of semiconductor materials, seepage theory and tunneling effect of conductive polymer composites and changes in interface contact resistance. Based on these sensing mechanisms, various flexible piezoresistive pressure sensors with high sensitivity, broad sensing range and fast response time have been developed. The selection of composition materials and microstructural design in flexible piezoresistive pressure sensor to implement the optimization of sensing performance are emphatically presented in this review. The composition materials including organic polymer material and inorganic nanomaterial based on two-dimensional (2D) materials such as graphene and MXene are intensively exhibited. In addition to the above characteristics, these kinds of pressure sensors exhibit high mechanical reversibility and low detection limit, which is essential for detecting the minor motions like respiratory rate and pulse. Moreover, the well-designed structures applied to the composition analysis are also overviewed, such as the sea urchin-like structure, spongy porous structure and regular structure. Various designed structures provide further properties like stability for the flexible pressure sensor. However, comparing with traditional pressure sensor, the mass production and application of flexible pressure sensor are confronting several barriers, like the high cost of raw materials and relatively complex manufacturing processes. How to achieve the low cost and low energy consumption simultaneously on the basis of excellent performance is still a challenge to expanding the applications of flexible pressure sensor. Novel sensing mechanism, functional materials and synthetic integration are expected to be developed in the future. And also, the potential application of flexible pressure sensor will be further expanded after endowing it with more functions.

Enhancing Part-to-Part Repeatability of Force-Sensing Resistors Using a Lean Six Sigma Approach

“…Compensating voltages for the sensors in Region (A) and (C) can also be found from (8). Nonetheless, we cannot directly replace U o 0N in ( 8) and set a targeted sensitivity, m, to obtain the new U.…”

“…Finally, given the mean sensitivity at 3 V for the sensors in Region (A), µ A , the model from (8), the target sensitivity, µ 3V , and the average rate of change of U o 0N as a function of U, we computed the new U resulting in U A = 2.5 V. Similarly, the same procedure was performed for the sensors in Region (C), but using µ C and the average rate of change of U o 0N for these sensors; this resulted in the new voltage of U C = 3.15 V. Later, experimental sensor characterization was performed at the new voltages U A and U C ; this was done for the sensors belonging to Regions (A) and (C), respectively. The experimental results are plotted in Figure 7.…”

“…The resulting nanocomposite exhibits a piezoresistive response that can be used to either measure compressive forces [6] or tensile loads [3,4,7]. Given the low profile and low cost of FSRs, their usage in research and industrial applications is currently increasing [8]. Multiple studies related to gait analysis [9][10][11], robotics [12,13], and other disciplines have reported the usage of polymer nanocomposites to perform strain/stress measurements [14][15][16][17].…”

“…Parameters resulting from the fit. Parameters a through c were obtained from a least-squares fit to(8) with coefficient of correlation R 2 . The mean sensitivity (µ) for each region (µ A , µ C ) was measured at U = 3 V.…”

Flexible BaTiO3-PDMS Capacitive Pressure Sensor of High Sensitivity with Gradient Micro-Structure by Laser Engraving and Molding

“…The sensitivity of traditional capacitive sensors utilizing solid dielectric layers is hindered by their restricted deformation capacity [ 23 , 24 , 25 ]. In order to enhance sensitivity, extensive research has been conducted on diverse micro-structures such as micro-spheres [ 26 ], micro-pillars [ 27 ], porous structures [ 28 ], micro-pyramids [ 29 ], nanoparticles [ 30 , 31 , 32 ], and micro-array structures [ 33 , 34 ]. However, it has been observed that these micro-structures primarily operate within the low-pressure range, thereby diminishing their sensitivity in the high-pressure range and consequently limiting the linear range [ 21 , 35 , 36 , 37 , 38 , 39 ].…”