Surface Wettability for Skin‐Interfaced Sensors and Devices

Abstract

The practical applications of skin-interfaced sensors and devices in daily life hinge on the rational design of surface wettability to maintain device integrity and achieve improved sensing performance under complex hydrated conditions. Various bioinspired strategies have been implemented to engineer desired surface wettability for varying hydrated conditions. Although the bodily fluids can negatively affect the device performance, they also provide a rich reservoir of health-relevant information and sustained energy for next-generation stretchable self-powered devices. As a result, the design and manipulation of the surface wettability are critical to effectively control the liquid behavior on the device surface for enhanced performance. The sensors and devices with engineered surface wettability can collect and analyze health biomarkers while being minimally affected by bodily fluids or ambient humid environments. The energy harvesters also benefit from surface wettability design to achieve enhanced performance for powering on-body electronics. This review first summarizes the commonly used approaches to tune the surface wettability for target applications toward skin-interfaced sensors and devices. By considering the existing challenges, one also discusses the opportunities as a small fraction of potential future developments, which can lead to a new class of skin-interfaced devices for use in digital health and personalized medicine.

Wearable Pressure Sensor Array with Layer-by-Layer Assembled MXene Nanosheets/Ag Nanoflowers for Motion Monitoring and Human–Machine Interfaces

“…Figure i shows the curve of the pressure applied to 2.3 kPa at different speeds (15–60 mm/min), demonstrating the excellent uniformity and stability of the sensor. In the long-term use of flexible wearable devices, the variation of sensing performance under different humidity conditions must be considered . To improve the humidity resistance of the sensor, we encapsulate the pressure sensor with a PI film.…”

“…In the long-term use of flexible wearable devices, the variation of sensing performance under different humidity conditions must be considered. 41 To improve the humidity resistance of the sensor, we encapsulate the pressure sensor with a PI film. Its current response to the 1 kPa pressure is basically unchanged under different humidity, indicating that this encapsulation method is simple and effective (Figure S6).…”

A humidity-resistant bio-inspired microfibrillar adhesive fabricated using a phenyl-rich polysiloxane elastomer for reliable skin patches

“…17,22,[32][33][34] However, the varying humidity conditions of the skin surface due to changes in ambient humidity and the secretion of sweat have often led to lower adhesion and poor contact between the skin surface and the electrodes, further resulting in fluctuations of monitoring data. 18,35 In one experiment, we first continuously collected RH data close to the skin surface at various parts of the body, including the forehead, neck, chest, upper arm and wrist, via a humidity/temperature probe equipped with a cover (Fig. 5a, the environmental temperature and humidity were kept at 25 1C and 45 AE 5% RH, respectively).…”

Additively Manufactured Flexible Electronics with Ultrabroad Range and High Sensitivity for Multiple Physiological Signals’ Detection

“…MXene/tissue paper sensors and self-powered sensors are also high-performance flexible sensors, and they have drawn considerable attention [40,41]. They have low production costs, low energy consumption, and minimal environmental impact [4,42,43].…”