The electrical feedthrough for live testing of the prototype; (inset) prototype of the sensor
Researchers from the Photovoltaic Research Laboratory of Kerala University have developed self-powered sensors that can be integrated with portable electronic devices.
R. Jayakrishnan, Associate Professor, Department of Physics, and his student Jishad S. Salam invented a self-powered UV-visible zinc sulphide photodetector that displays greater photosensitivity than a similar sensing system developed earlier by researchers in China.
The invention, published in the peer-reviewed Journal of Materials Science, has brought a successful culmination to a six-year-long doctoral research undertaken by Mr. Salam and his guide as part of the former’s thesis.
Explaining the relevance of the research, Prof. Jayakrishnan says portable and wearable devices such as smartwatches provide enhanced convenience and paves the way for applications such as health monitoring, human machine interaction, and Internet of Things (IoT).
However, the source of energy supply for such devices has been a major obstacle in integration. Replaceable batteries are at present the most common power source for these electronic devices. The rigid characteristics, limited lifetime, and potential environmental pollution of these batteries do not conform to the principles of sustainable development. Hence, the ongoing research has been targeted towards environmentally friendly, renewable energy sources that can power such electronic devices, he says.
“The photodetector developed by us is a champion in terms of its photosensitivity to visible light,” claims the research team in the published paper.
“Our photosensitivity is 10 6, which is higher than the previously reported photosensitivity of 10 5 by the researchers from Fudan University in Shanghai, China, using the same material. The heart of the device is a thin film layer of zinc sulphide semiconducting material grown over a transparent conducting oxide layer grown over ordinary glass substrate,” Prof. Jayakrishnan says.
The architecture of the developed device can be utilised by the industry for different applications in accordance with its needs. “In the primary mode, active sensing can be realised by using the output electrical signal itself from the device as the sensing signal, whereas in the secondary mode, the device will double up as an energy harvester that can supply energy to a sensor module,” says the researchers.
