3D-Printed Flexible Microfluidic Health Monitor for In Situ Sweat Analysis and Biomarker Detection.

Wearable sweat biosensors have shown great progress in noninvasive, in situ, and continuous health monitoring to demonstrate individuals' physiological states. Advances in novel nanomaterials and fabrication methods promise to usher in a new era of wearable biosensors. Here, we introduce a three-dimensional (3D)-printed flexible wearable health monitor fabricated through a unique one-step continuous manufacturing process with self-supporting microfluidic channels and novel single-atom catalyst-based bioassays for measuring the sweat rate and concentration of three biomarkers. Direct ink writing is adapted to print the microfluidic device with self-supporting structures to harvest human sweat, which eliminates the need for removing sacrificial supporting materials and addresses the contamination and sweat evaporation issues associated with traditional sampling methods. Additionally, the pick-and-place strategy is employed during the printing process to accurately integrate the bioassays, improving manufacturing efficiency. A single-atom catalyst is developed and utilized in colorimetric bioassays to improve sensitivity and accuracy. A feasibility study on human skin successfully demonstrates the functionality and reliability of our health monitor, generating reliable and quantitative in situ results of sweat rate, glucose, lactate, and uric acid concentrations during physical exercise.

Superhydrophobic Foams with Chemical- and Mechanical-Damage-Healing Abilities Enabled by Self-Healing Polymers.

The fabrication of superhydrophobic materials capable of spontaneously healing both chemical and mechanical damages at ambient conditions has been a great challenge but highly desired. In this study, we propose that a self-healing hydrophobic polymer can be used to induce self-healing in a superhydrophobic material. As a demonstration, stable and porous self-healing superhydrophobic foams are fabricated by casting a mixture of healable poly(dimethylsiloxane) (PDMS)-based polyurea, multiwalled carbon nanotubes (MCNTs), and table salt, followed by solvent evaporation and removal of the salt template. The PDMS-based polyurea is able to heal mechanical damage by reforming hydrogen bonds and can also reverse chemical damage through surface reorganization. Thus, the chemically and mechanically damaged foams can spontaneously restore their superhydrophobicity and structural integrity at ambient conditions. Moreover, because of the satisfactory photothermal conversion of MCNTs, the temperature of the self-healing superhydrophobic foams can rapidly reach 60 °C under sunlight, which greatly increases the healing speed and healing efficiency of the foam.