For multifunctional wearable sensing systems, problems related to wireless and continuous communication and soft, noninvasive, and disposable functionality issues should be solved for precise physiological signal detection. To measure the critical transitions of pressure, temperature, and skin impedance when continuous pressure is applied on skin and tissue, we developed a sensor for decubitus ulcers using conventional analog circuitry for wireless and continuous communication in a disposable, breathable fabric-based multifunctional sensing system capable of conformal contact. By integrating the designed wireless communication module into a multifunctional sensor, we obtained sensing data that were sent sequentially and continuously to a customized mobile phone app. With a small-sized and lightweight module, our sensing system operated over 24 h with a coin-cell battery consuming minimum energy for intermittent sensing and transmission. We conducted a pilot test on healthy subjects to evaluate the adequate wireless operation of the multifunctional sensing system when applied to the body. By solving the aforementioned practical problems, including those related to wireless and continuous communication and soft, noninvasive, and disposable functionality issues, our fabric-based multifunctional decubitus ulcer sensor successfully measured applied pressure, skin temperature, and electrical skin impedance.

Despite various strategies to address sticking failure in stainless steels (STSs), difficulties in understanding its fundamental mechanisms hinder precise solutions during STS fabrication. This study investigated the effect of chromium (Cr) content on the microstructures and failure modes of oxide scales under a tensile load, simulating the hot-rolling process. The dynamic, real-time behavior of crack initiation, propagation, and interfacial delamination in the oxide scales under tension was analyzed using an in situ scanning electron microscopy (SEM) tensile test. With a high Cr content, iron (Fe) oxide and chromium(III) oxide (Cr2O3) form a layered structure, which is delaminated along the interfaces between the thin Cr2O3 layer and the bulk after perpendicular cracking. The saturated crack densities obtained from in situ SEM provide interfacial strength, while the elastic modulus and hardness obtained from nanoindentation provide vertical fracture strength. In combination with an ex situ elemental image analysis, the in situ SEM results reveal three different failure modes of the four different STSs. The results confirm that sticking failure is more likely to occur as the Cr content increases.