Self‐Powered Wearable Electronics Based on Moisture Enabled Electricity Generation

• Published in: Advanced materials (Weinheim) 2018-05, Vol.30 (18), p.e1705925-n/a
• Main Authors: Shen, Daozhi, Xiao, Ming, Zou, Guisheng, Liu, Lei, Duley, Walter W., Zhou, Y. Norman
• Format: Article
• Language: English
• Subjects: Batteries; Breathing; Electric generators; Electric potential; Electricity; Electronic devices; Environmental management; fluidic electricity; Generators; Humidity; Materials science; Moisture; nanogenerators; Nanowires; self‐powered sensors; Sensors; Titanium dioxide; Wearable technology
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201705925

Most state‐of‐the‐art electronic wearable sensors are powered by batteries that require regular charging and eventual replacement, which would cause environmental issues and complex management problems. Here, a device concept is reported that can break this paradigm in ambient moisture monitoring—a new class of simple sensors themselves can generate moisture‐dependent voltage that can be used to determine the ambient humidity level directly. It is demonstrated that a moisture‐driven electrical generator, based on the diffusive flow of water in titanium dioxide (TiO2) nanowire networks, can yield an output power density of up to 4 µW cm−2 when exposed to a highly moist environment. This performance is two orders of magnitude better than that reported for carbon‐black generators. The output voltage is strongly dependent on humidity of ambient environment. As a big breakthrough, this new type of device is successfully used as self‐powered wearable human‐breathing monitors and touch pads, which is not achievable by any existing moisture‐induced‐electricity technology. The availability of high‐output self‐powered electrical generators will facilitate the design and application of a wide range of new innovative flexible electronic devices. A highly efficient moisture‐driven electrical generator based on diffusive flow of water in flexible TiO2 3D frameworks is reported. The electricity provided by human breath to the device can light a commercial light‐emitting diode. This new type of device is used as self‐powered wearable human‐breathing monitors and touch pads, which is not achievable by way of any existing moisture‐induced‐electricity technology.