Highly Sensitive Wearable Textile-Based Humidity Sensor Made of High-Strength, Single-Walled Carbon Nanotube/Poly(vinyl alcohol) Filaments

TLDR

Textile‑based humidity sensors are promising for smart wearables, offering applications in wound care, bed‑wetting management, skin pathologies, and microclimate control. We report, for the first time, a wearable humidity sensor fabricated from high‑strength, ultratough SWCNT/PVA filaments produced by a wet‑spinning process. The sensor’s conductive SWCNT networks are tuned by water‑induced swelling of the PVA chains, which alters intertube spacing and modulates resistance. It shows a diameter doubling when wet, a resistance increase of over 220× after water spray, and a 24× resistance change within 40 s at a 1:5 SWCNT/PVA ratio, enabling rapid detection of water leakage on hydrophobic textiles.

Abstract

Textile-based humidity sensors can be an important component of smart wearable electronic-textiles and have potential applications in the management of wounds, bed-wetting, and skin pathologies or for microclimate control in clothing. Here, we report a wearable textile-based humidity sensor for the first time using high strength (∼750 MPa) and ultratough (energy-to-break, 4300 J g-1) SWCNT/PVA filaments via a wet-spinning process. The conductive SWCNT networks in the filaments can be modulated by adjusting the intertube distance by swelling the PVA molecular chains via the absorption of water molecules. The diameter of a SWCNT/PVA filament under wet conditions can be as much as 2 times that under dry conditions. The electrical resistance of a fiber sensor stitched onto a hydrophobic textile increases significantly (by more than 220 times) after water sprayed. Textile-based humidity sensors using a 1:5 weight ratio of SWCNT/PVA filaments showed high sensitivity in high relative humidity. The electrical resistance increases by more than 24 times in a short response time of 40 s. We also demonstrated that our sensor can be used to monitor water leakage on a high hydrophobic textile (contact angle of 115.5°). These smart textiles will pave a new way for the design of novel wearable sensors for monitoring blood leakage, sweat, and underwear wetting.