Researchers atGauhati Universityhave developed aflexible, low-cost sensorusing simple materials like pencil, paper, and graphene, marking a significant step towardaffordable and sustainable sensor technology. The innovation has potential applications inhealthcare, agriculture, and wearable monitoring.

Led byDr Hemen Kumar Kalitafrom the Department of Physics, along with PhD scholarsRajnandan LahkarandBiswajit Dehingia, the team designed agraphene-based capacitive sensoron a paper substrate by drawing interdigitated electrodes with ordinary pencils and using graphene oxide as the active sensing material. This approach eliminates the need for expensive metals, cleanroom facilities, and chemical-intensive fabrication, resulting in alightweight, environmentally friendly, and disposable sensorsuitable for large-scale use.

Published inACS Applied Electronic Materials, the sensor demonstratesexceptionally high sensitivity to humidity and moisture, with a response exceeding1,500%at high relative humidity. This outperforms many existing paper-based and flexible sensors, which often have limited sensitivity or single-function capability.

The device has been successfully tested inreal-world applicationsincluding soil moisture measurement, plant drought detection, human breathing and skin moisture monitoring, non-contact proximity sensing, and smart diaper wetness detection. Its ability to perform multiple functions at low cost highlights itstechnological and practical significance.

The project was supported by theDepartment of Science and Technology (DST)through theINSPIRE programme, Early Career Research Award, and DST-PURSE initiative, providing funding, materials, and manpower for the study. The researchers emphasize that this work demonstrates howlocally adaptable, low-cost methods can produce high-performance sensorswith broad impact in healthcare and agriculture.