Ultrastretchable and Stable Conductive Elastomer Based on Micro-Ionicgel for Wide-Working-Range Sensors

A liquid metal/polypyrrole electrospun TPU composite conductive network for highly sensitive strain sensing in human motion monitoring

Developing soft wearable sensors with high sensitivity, low cost, and a wide monitoring range is crucial for monitoring human health. Despite advances in strain sensor technology, achieving high sensitivity and a wide operating range in a single device remains a major challenge in its design and preparation. Herein, a liquid metal (LM) is innovatively ultrasonically anchored to the gaps and surfaces of thermoplastic polyurethane (TPU) electrospun fibers, and then a conductive pathway is constructed through polypyrrole (PPy) self-polymerization to prepare a composite film. The strain sensor developed by ultrasonic anchoring and original polymerization technology shows a high strain coefficient (GF = 4.36 at 12.5% strain) and a low detection limit (less than 1% strain). Importantly, this sensor can monitor joint motion and subtle skin deformations in real time. In addition, the integration of strain sensors and N95 masks enables real-time monitoring of human respiration.

High-sensitivity piezoresistive sensors based on cellulose handsheets using origami-inspired corrugated structures

Cellulose-based composites have attracted significant attention in the fabrication and advancement of wearable devices due to their sustainable, degradable, and cost-effective properties. However, achieving a cellulosic sensor with reliable sensory feedback remains challenging owing to the deficiency in reversible microstructures during response processes. In this study, we developed a piezoresistive sensor consisting of nearly pure cellulose handsheets using origami-inspired corrugated structures to achieve durable and sensitive piezoresistive responses. Multi-walled carbon nanotubes (MWCNTs) were used as conducting agents. With the addition of 7 wt% MWCNTs, 36.27 % of the cellulose fiber surface was covered and the conductivity of cellulose handsheets was increased to 8.7 S/m. The obtained conductive cellulose handsheets were transformed into corrugated structures and integrated orthogonally to construct the piezoresistive sensors with reversible electrical paths for electrons. The restorable corrugated structure endowed the sensors with a wide workable pressure range (0-10 kPa), high sensitivity (6.09 kPa-1 in a range of 0-0.92 kPa), fast response time (<280 ms), and good durability (>1000 cycles). Furthermore, the practical applications of the proposed sensors as wearable devices were demonstrated through phonation, real-time sports monitoring, and step pressure tests.

Facile Preparation of Dual Functional Wearable Devices Based on Hindered Urea Bond-Integrated Reprocessable Polyurea and AgNWs

With the advancement of material science and electronic technology, wearable devices have been integrated into daily lives, no longer just a stirring idea in science fiction. In the future, robust multifunctionalized wearable devices with low cost and long-term service life are urgently required. However, preparing multifunctional wearable devices robust enough to resist harsh conditions using a commercially available raw material through a simple process still remains challenging. In this work, reprocessable polyurea (HUBTPU) with a hard segment of hindered urea bonds (HUBs) and a soft segment of polyether is synthesized via a facile one-pot method. The robust dual functional wearable devices were obtained by simply spray-coating silver nanowires (AgNWs) on HUBTPU elastomer substrates. Due to the dynamic combination and decomposition of the HUBs and hydrogen bonds at 130 °C, the robust elastomer demonstrates favorable adhesion to various substrates. Especially, the partially embedded AgNW structure is also achieved by using ethanol as a spray solvent. The adhesion of HUBTPU substrates and embedded structure leads to stronger interfacial adhesion and stability compared to non-adhesive substrates. The as-obtained HUBTPU electrodes are able to be heated to 115 °C by applying a low voltage and sensing the strain deformation caused by human movement, which means that the electrodes are endowed with both electrical heating capability and strain sensing functionality. Therefore, this strategy reveals a potential way to prepare multifunctional wearable devices using other conductive particles and adhesive functional polymer substrates.

Tailor-made urethane-linked alkyl-celluloses: A Promising Stabilizer for Oil-in-oil Pickering Emulsions

Oil-in-oil emulsions or nonaqueous emulsions are formulated from two immiscible organic solvents, which provide an ideal platform for water-sensitive systems such as readily hydrolyzable reagents and polymerization in anhydrous conditions....