Flexible and Wearable Optical System Based on U‐Shaped Cascaded Microfiber Interferometer

Abstract Future wearable devices for health monitoring, robotics, and ultraprecise industrial positioning necessitate flexible optical systems. Here, an optical microfiber interferometer‐based wearable system is demonstrated with wavelength interrogation that overcomes the limits of commonly reported electrical, optical, and material‐based flexible devices. The microfiber in a finely tuned configuration is enclosed in polydimethylsiloxane (PDMS) thin film to provide a means of controlling interference between fundamental and higher‐order modes. Using this approach, it is possible to create a simple, adaptable, and cost‐effective optical device with a direction recognizable bending sensitivity of up to 1.01 nm per degree, and remarkable temperature sensitivity of −3.07 nm °C −1 . The ultrahigh sensitivity, mechanical robustness, and outstanding flexible and biocompatible nature make this sensor system a leading candidate for wearable medical devices for elder‐care facilities, physiological monitoring, athletic training, and rehabilitation programs.