A Highly Sensitive, Breathable, and Biocompatible Wearable Sensor Based on Nanofiber Membrane for Pressure and Humidity Monitoring

Abstract

With the advent of information technology, the progress of wound healing diagnosis and human health monitoring bring forward the need for sensitive humidity sensing. Simultaneously, developing a highly sensitive humidity sensor with multifunctional characteristics, especially pressure sensing, biosafety, and comfort, remains challenging so far. Herein, a wearable humidity‐pressure sensor based on an all‐nanofiber membrane with excellent sensitivity, breathability, and biosafety is fabricated by the combination of electrospinning and screen‐printing. The citric acid (CA) and sodium polystyrene sulfonate (PSS) are used as moisture‐sensitive materials to make thermoplastic polyurethane (TPU) nanofiber membranes sensitive to water molecules. The synergistic effect of the uneven surface and microstructure of the electrospun TPU nanofiber membrane confers the sensor with high sensitivity to both humidity and pressure stimuli. The CA/TPU humidity‐pressure sensor exhibits remarkable breathability and high sensitivity (2.15%/RH in the range of 50–90%RH, 10.53 kPa−1 in the range of 0–2.25 kPa), as well as fast humidity response (3.8 s) with little hysteresis and rapid pressure response (88 ms). The high biosafety makes it applicable to skin and wounds. Furthermore, the sensor can detect various human activities in real‐time and offer a new sensing platform for respiratory monitoring and smart wound dressings.

Washable and Breathable Electret Sensors Based on a Hydro-Charging Technique for Smart Textiles

“…The air permeability of the netting yarn spacer is not listed because it is almost completely breathable, with the measured air permeability value exceeding 10,000 mm/s. Figure b shows the comparison of the air permeability of breathable sensors reported in recent years. − It should be noted that the air permeability values measured at different test pressure drops are different, and the higher the test pressure drop, the higher the measured air permeability value. The results of the comparison show that the air permeability of the HCES outperforms the reported breathable sensors.…”

Piezoelectric Effect Polyvinylidene Fluoride (PVDF): From Energy Harvester to Smart Skin and Electronic Textiles

“…Ding et al. [ 174 ] prepared a humidity‐pressure sensor that exhibits remarkable breathability and high sensitivity. These properties make the sensor applicable to smart skin and wound dressing.…”

“…Moreover, the triboelectric nanogenerator performs excellent voltage output and short-circuit current. Ding et al [174] prepared a humidity-pressure sensor that exhibits remarkable breathability and high sensitivity. These properties make the sensor applicable to smart skin and wound dressing.…”

Integrating Ti3C2Tx MXene Nanosheets with Thermoplastic Polyurethane Nanofibers as Wearable Humidity Sensors for Noninvasive Sleep Monitoring and Noncontact Sensing

“…It is necessary to ensure the safety of the sensor. 30 According to the authors' previous report, 21 the biocompatibility is assessed using visible cell culture of human immortalized epidermal (HaCaT) cells (National Infrastructure of Cell Line Resource, China) in vitro (Figure 3e). There is no obvious cytotoxic effect against HaCaT cells, demonstrating that Ti 3 C 2 T x /TPU has excellent biocompatibility.…”

“…An inverted fluorescence microscope (IX81-ZDC, Olympius) was used to assess the cytotoxicity; the details are mentioned in the authors' previous study. 21 2.4. Sensing Performance Measurement.…”