A Wearable Electrowetting on Dielectrics Sensor for Real‐Time Human Sweat Monitor by Triboelectric Field Regulation

Abstract

Wearable sweat sensors can analyze the abundant composition of solutes and metabolites in sweat to reflect the health state of the wearers in real time. The realization of active motion control for sweat droplets is significant for a multifunctional sweat monitoring device with several analysis chambers. Here, a wearable droplet-based human sweat monitoring platform (WSMP), by combining an electrowetting on dielectrics (EWOD) device and a triboelectric nanogenerator (TENG), is demonstrated. It allows to collect and transport sweat droplets in different chambers by dielectric wetting effect and eventually merge and react with a pH indicator. The mechanical and electrical model of WSMP is introduced to describe the relationship between the open-circuit voltage of the TENG and the voltage applied on the EWOD device. The highvoltage electrical field generated by the TENG can change the wettability of solid-liquid interfaces and realize the controlling of droplet motion. The contact angle of electrolyte droplets changes over 30% with the triboelectric voltage of 5 kV. The driving, merging, and color reaction can be realized by actively controlling the motion of droplets. Finally, a wearable WSMP worn on the shank successfully demonstrates the preliminary detection of the pH level of human sweat.

Triboelectric Nanogenerator Enabled Wearable Sensors and Electronics for Sustainable Internet of Things Integrated Green Earth

“…Moving forward, in addition to the conventional working mechanisms including resistive, impedance, or electrochemical sensors that require external power supply, self-powered sensors enabled by TENG are also developed as wearable epidermal devices for healthcare applications. [146] In Figure 6e, Wang et al have proposed a stretchable, self-healing, and skin-mounted active sensor for muscle function assessment. [117] The stretchable TENG is composed of the self-healable ionic hydrogel as electrode layer, micropatterned silicone rubber and middle parylene-C as triboelectric layers, and dielectric elastomer (VHB) and top parylene as the substrate and encapsulating layers.…”

“…Moving forward, in addition to the conventional working mechanisms including resistive, impedance, or electrochemical sensors that require external power supply, self‐powered sensors enabled by TENG are also developed as wearable epidermal devices for healthcare applications. [ 146 ] In Figure 6e, Wang et al. have proposed a stretchable, self‐healing, and skin‐mounted active sensor for muscle function assessment.…”

Real‐Time Non‐Driving Behavior Recognition Using Deep Learning‐Assisted Triboelectric Sensors in Conditionally Automated Driving

“…TENGs based on triboelectric effect and electrostatic induction effectively collect and convert micromechanical energy into electricity. [28,29] Due to simple fabrication, low cost, high sensitivity, and selfpower, the TENGs-based sensors [30][31][32] have been widely used in various fields such as human-computer interaction, [33] respiratory, [34] vibration and sound detection, [35,36] tactile and pressure sensing, [37,38] wearable detection devices [39][40][41] and etc. Moreover, the TENG exhibits high electric output in low frequency and microscale motion detection that can catch tiny signals from the human body.…”

Triboelectric Nanogenerator-Based Near-Field Electrospinning System for Optimizing PVDF Fibers with High Piezoelectric Performance

“…As one of the new energy technologies, triboelectric nanogenerator (TENG) can directly convert various forms of micromechanical energy into electrical energy in life by using the triboelectrification and electrostatic induction effects. − Compared with commercial DC high voltage power supplies, TENG with high voltage and low current characteristics makes the circuit’s limited current and charge transfer per cycle better in protecting the safety of personnel. − In recent years, various potential applications of TENG in high voltage electrostatic fields have been developed, such as electrospinning, low-temperature triboelectric plasma, nano-electrospray ionization of mass spectrometry, microfluidic chips, sterilization, and other fields. − In terms of electrospinning, Wang et al designed a self-powered electrospinning system driven by a rotating-disc TENG in 2017 . This technology realizes the combination of TENG and electrospinning, which can provide 8 kV high voltages for the electrospinning of nanofibers.…”