Rational Design of All Resistive Multifunctional Sensors with Stimulus Discriminability

Abstract

A rational approach is proposed to design soft multifunctional sensors capable of detection and discrimination of different physical stimuli. Herein, a flexible multifunctional sensor concurrently detecting and distinguishing minute temperature and pressure stimuli in real time is developed using electrospun carbon nanofiber (CNF) films as the sole sensing material and electrical resistance as the only output signal. The stimuli sensitivity and discriminability are coordinated by tailoring the atomic-and device-level structures of CNF films to deliver outstanding pressure and temperature sensitivities of −0.96 kPa −1 and −2.44% °C−1 , respectively, enabling mutually exclusive sensing performance without signal cross-interference. The CNF multifunctional sensor is considered the first of its kind to accomplish the stimulus discriminability using only the electrical resistance as the output signal, which is most convenient to monitor and process for device applications. As such, it has distinct advantages over other reported sensors in its simple, cost-effective fabrication and readout system. It also possesses other invaluable traits, including good bending stability, fast response time, and long-term durability. Importantly, the ability to simultaneously detect and decouple temperature and pressure stimuli is demonstrated through novel applications as a skin-mountable device and a flexible game controller.

Electrospun Nanofibers for Periodontal Treatment: A Recent Progress

“…43,44 The process has the benefits of having a basic apparatus, simple operation, and cost-effectiveness. Consequently, electrospinning has been widely used in many fields, such as medical engineering, [45][46][47] environmental treatment, 48,49 biosensors, 50,51 food packaging and herbal medicine. 52,53 The nanofibrous membranes prepared via electrospinning has a small pore diameter, high specific surface area, and easy surface modification, which is highly suitable for use in periodontal barrier membranes.…”

Highly Sensitive Temperature–Pressure Bimodal Aerogel with Stimulus Discriminability for Human Physiological Monitoring

“…However, these dual-sensing materials usually produce fused signals of relative resistance or current changes without discrimination . Till now, dual-sensing materials with combined pyro-piezoresistive effects to simultaneously detect and discriminate pressure and thermal signals have rarely been reported …”

“…3 Among the reported electromechanical and electrothermal sensors, the piezoresistive and pyroresistive sensors, which produce similar signals of relative resistance changes in response to pressure and thermal stimuli, have attracted much interest in practical wearable sensing applications because of their simple and scalable fabrication processes, easy signal collection methods, and broad selection of applicable piezoresistive and pyroresistive materials. 16,23,24 Blending conductive nanomaterials with soft polymers to prepare thermosensitive conductive composites can be a facile method to make pyroresistive and piezoresistive composites. However, these dual-sensing materials usually produce fused signals of relative resistance or current changes without discrimination.…”

“…24 Till now, dual-sensing materials with combined pyro-piezoresistive effects to simultaneously detect and discriminate pressure and thermal signals have rarely been reported. 16 Herein, we report the design and fabrication of a dualsensing material with combined but independent pyroresistive and piezoresistive effects that can simultaneously detect and discriminate temperature and pressure stimuli in the narrow physiological temperature range of 30−40 °C with both high sensitivity and accuracy (Figure 1). The dual-sensing material is based on a conductive nanocomposite aerogel consisting of a conductive nanomaterial, Ti 3 C 2 T x MXene nanosheet as the main building block, and a thermoresponsive material, semicrystalline poly(ethylene oxide) (PEO) as the intercalation material, which were used to fabricate the pyroresistive and piezoresistive MXene/PEO aerogel.…”

“…One common strategy to develop wearable multimodal sensors is to integrate multiple single-modal sensors into one sensing array. − Although this strategy has been achieved for simultaneous and discriminable multisignal sensing, the complex and expensive fabrication processes required for these sensing arrays limit their use for real-world commercial applications. , Recently, one effective approach has been proposed as an alternative approach to fabricate consolidated multimodal sensors with decoupled force and temperature sensing ability by utilizing functional materials with inherent electromechanical and electrothermal effects as a single sensing material. ,,,, Three types of such functional materials exhibit dual-sensing capability: thermoelectric materials (e.g., PEDOT:PSS) with inherent thermoelectric and piezoresistive features, , ferroelectric materials (e.g., BaTiO 3 ) with intrinsic pyroelectric and piezoelectric properties, and dedicatedly designed composite materials (such as our previously reported conductive nanocomposite) with combined piezoresistive and thermoelectric effects, or piezoresistive and pyroelectric effects . Among the reported electromechanical and electrothermal sensors, the piezoresistive and pyroresistive sensors, which produce similar signals of relative resistance changes in response to pressure and thermal stimuli, have attracted much interest in practical wearable sensing applications because of their simple and scalable fabrication processes, easy signal collection methods, and broad selection of applicable piezoresistive and pyroresistive materials. ,, Blending conductive nanomaterials with soft polymers to prepare thermosensitive conductive composites can be a facile method to make pyroresistive and piezoresistive composites. However, these dual-sensing materials usually produce fused signals of relative resistance or current changes without discrimination .…”