Self‐Assembled Wavy Optical Microfiber for Stretchable Wearable Sensor

Abstract

Smart wearable devices have made remarkable success in medical‐grade human vital signal monitoring and have promoted the realization of precision medicine and telemedicine. The flexibility and stretchability are significant for wearable devices, which determine the adhesion to the skin and influence the signal accuracy. Here, a stretchable and ultrathin optical sensor based on a self‐assembled wavy microfiber is proposed. Thanks to the “bottom–up” strategy, the wave structure of the microfiber can be adjusted artificially, paving the way for the design of stretchable optical devices. Due to the microbend loss of the microfiber, the optical sensor has a sensitivity of ≈257 per unit strain and a good repetition (the standard deviation is 1.7% over 100 cycles). With the great sensor performance, the wrist pulse with a high signal‐to‐noise ratio is detected and the blood pressure is monitored successfully via the pulse arrival time, showing a potential application for human health monitoring.

Recent advances in skin-like wearable sensors: sensor design, health monitoring, and intelligent auxiliary

“…Adjustable sensitivity (0.01 to 0.47%) was used for bending sensing, as well as high resolution for temperature detection so that it could monitor breathing, arm movement, and body temperature in real time. Zhu et al 59 proposed a stretchable wearable sensor of self-assembled wavy optical microfiber. The optical sensor had high sensitivity and good repeatability, which depended on the microfibril characteristics of the microfiber.…”

Wearable Optical Sensing in the Medical Internet of Things (MIoT) for Pervasive Medicine: Opportunities and Challenges

“…Additionally, some creative designs, such as skin-like and microfluidic-integrated sensors, have pointed to the emerging solutions. The skin-like WOS is composed of micro/nanofibers (MNFs) attached to a PDMS film and presents excellent tensile properties of about 10% (1% for normal fiber). , Such sensors rely on van der Waals force interaction and adhere tightly to human skin without any adhesives, resulting in advantages of high sensitivity and no skin irritation, which are an urgent need in long-time cardiac monitoring in ICUs. Another study proposed a graphene-based flow sensor (GFS) for blood flow velocity and pressure measurements .…”

“…Sensors placed on different body locations are framed using different colors corresponding to the diagram in the middle. (a–d) Optical sensors placed on the wrist (green dotted box) for HR detection, including FBG, PPG, and microfiber sensors . (e–g) Photrodes placed on the chest (red dotted box) for ECG monitoring.…”

Advances in Medical Wearable Biosensors: Design, Fabrication and Materials Strategies in Healthcare Monitoring

“…Their application in textiles will allow for novel wound-dressing fabrics with the ability to monitor healing without degradation in optical properties. A similar stretchable, wearable, ultrathin sensor was developed by using a wavy optical microfiber by Zhu et al (2021) using the bottom-up approach and was capable of successfully monitoring BP via wrist pulses [ 105 ]. Some other optical micro- and nanofiber-based wearable optical sensors used for monitoring respiration and bodily movements can be found in these papers [ 106 , 107 ].…”