Highly Sensitive Microstructure-Based Flexible Pressure Sensor for Quantitative Evaluation of Motor Function Recovery after Spinal Cord Injury

Abstract

Behavioral assessment, such as systematic scoring or biomechanical measurement, is often used to evaluate the extent of the damage and the degree of recovery after spinal cord injury. However, the use of these methods in standardized evaluation is limited because they are subjective and require complex test systems to implement. Here, we report a novel, flexible, microstructure-based pressure sensor and demonstrate its superior sensitivity (235.12 kPa−1 for 5.5~135 Pa and 2.24 kPa−1 for 0.6~25 kPa), good waterproofness, fast response and recovery times (response time: 8 ms, recovery time: 12 ms), stable response over 8000 loading/unloading cycles, and wide sensing range. These features readily allow the sensor to be comfortably attached to the hindlimbs of mice for full-range, real-time detection of their behavior, such as crawling and swimming, helping to realize quantitative evaluation of animal motor function recovery after spinal cord injury.

Recent Progress in Flexible Microstructural Pressure Sensors toward Human–Machine Interaction and Healthcare Applications

“…The most common strategy is the template (e.g., silicon/AAO templates, and bionic patterns) assisted method. [ 34,35 ] The advantages of this strategy are low cost and mass production, and the templates usually can be reused. Besides, the magnetic field regulation method has also received extensive attention due to its advantages of controllability and simple preparation.…”

“…In general, the polymer (e.g., polydimethylsiloxane (PDMS)) gel is formed on a silica template to obtain a microstructural polymer film as an important part of FMPSs. [ 34,35 ] The silica template can be reused, and multiple operations will not affect the uniformity of the transferred microstructural film. For example, Fan et al.…”

“…Carbon materials (e.g., carbon black (CB), [ 101 ] graphene, [ 102 ] and carbon nanotubes [ 34 ] ) are frequently applied as induction elements and conductive layers in the preparation of FMPSs because of their excellent electrical and mechanical characteristics. The human skin can well sense changes in the outside world, such as pressure, temperature, and humidity due to a reticular layer.…”

“…Thus the flexible microstructural pressure sensors (FMPSs) prepared by various routes have the attractive advantages of wide contact area, strong recovery, and high sensitivity, which is becoming a research hotspot. [ 30–35 ]…”

A Flexible Pressure Sensor with Ink Printed Porous Graphene for Continuous Cardiovascular Status Monitoring

“…Due to high sensitivity and small volume, low dimensional materials are widely investigated in the flexible electronics community, such as metal nanomaterials, carbon nanotubes, and graphene. Metal nanomaterials such as AgNPs, AgNWs, and AuNWs process high sensitivity, yet their high costs prevent the sensor from having wide-range application [ 17 , 18 , 19 , 20 , 21 ]. Carbon nanotubes (CNT) such as single-wall CNT (SWCNT) and multi-wall CNT (MWCNT) are cheap, but their electromechanical properties are hard to control, which is still a dilemma in large-scale manufacturing [ 22 , 23 ].…”