Leveraging a temperature-tunable, scale-like microstructure to produce multimodal, supersensitive sensors

Abstract

The microstructure of a flexible film plays an important role in its sensing capability. Here, we fabricate a temperature-dependent wrinkled single-walled carbon nanotube (SWCNT)/polydimethyl-siloxane (PDMS) film (WSPF) and a wrinkle-dependent scale-like SWCNT/PDMS film (SSPF) successfully, and address the formation and evolution mechanisms of each film. The low elastic modulus and high coefficient of thermal expansion of the PDMS layer combined with the excellent piezoresistive behavior of the SWCNT film motivated us to investigate how the scale-like microstructure of the SSPF could be used to design multimodal-sensing devices with outstanding capabilities. The results show that SSPFs present supersensitive performance in mechanical loading (an effective sensitivity of up to 740.7 kPa) and in temperature (a tunable thermal index of up to 29.9 × 10 K). These exceptional properties were demonstrated in practical applications in a programmable flexile pressure sensor, thermal/light monitor or switch, etc., and were further explained through the macroscopic and microscopic piezoresistive behaviors of scale-like SWCNT coatings.

Flexible Normal‐Tangential Force Sensor with Opposite Resistance Responding for Highly Sensitive Artificial Skin

“…For example, by placing a piece of e‐skin on the artery of a human wrist, it can monitor the wrist pulse with high accuracy. As presented in Figure b, the collected pulsing waveforms clearly show an accurate recording of wrist pulse over tens of pulse periods, in which a characteristic pulse pressure shape was obtained with three clearly distinguishable peaks (Figure c; Movie S4, Supporting Information), implying potential applications for detailed medical heart diagnostics . On the other hand, our e‐skin can feel very gentle tickling with an ultrahigh sensitivity.…”

Carbon Nanotube‐Modified Fabric for Wearable Smart Electronic‐skin with Exclusive Normal‐Tangential Force Sensing Ability

“…For example, wrist pulse signals can be acquired with high accuracy by attaching a piece of the e‐skin on the artery of a human wrist (Figure a). As presented in Figure b and Video S4 in the Supporting Information, the collected data of pulsing waveforms demonstrated a precise corresponding relationship between the signal and the wrist pulse, and a characteristic pulse pressure shape with three distinguishable peaks was observed (the inset in Figure b), implying potential applications in precise medical heart diagnostics . Due to its unique response to tangential shearing force loading, the fabric can “feel” gentle friction.…”

Artificial Sensory Memory

“…To achieve this, specific structures and materials were exploited. For example, a mass of microstructures was utilized such as micropyramidal, microdome, microcavity, microcracks, thickness‐gradient structures, even metamaterial structure . Biomaterials, nanocomposites, triboelectric and piezoelectric materials, stimuli‐responsive polymers, hydrogels, and so on, were exploited to enhance the functionalities and to extend the limits owned by traditional silicon‐based materials .…”