An Indian researcher from IIT Bombay has developed low-cost soft, flexible, and wearable sensors that can be used to diagnose pulse rate variations in humans. Being a high sensitivity flexible pressure/strain sensor, it may also be utilised for small and large-scale motion monitoring, with applications in robotics, prosthetics, minimally invasive surgery, and identification of tumor/cancerous cells.
Dr. Dipti Gupta of IIT Bombay used low-cost polyurethane foam and nanomaterial-based inks that can coat many substrates to create these tactile (pressure and strain) sensors with funding from the Department of Science and Technology (DST) under the Advanced Manufacturing Technologies programme. Reduced graphene oxide (rGO) was used as the sensing material.
The fabrication of sensors based on reduced graphene oxide (rGO) as the sensing material was arduous due to the intrinsic hydrophobic behavior of graphene oxide inks, as well as the clusters of graphene oxide flakes following the reduction.
To make rGO ink with a hydrophilic nature, researchers utilised hydrazine as a reducing agent and a dual-component additive containing the chemicals benzisothiazolinone and methylisothiazolinone in suitable proportions.
A very simple, low-cost approach for fabricating a pressure sensor based on polyurethane (PU) foam coated with the MWNTrGO ink (MWNT [email protected] foam) was discovered using this hydrophilic rGO ink combined with multiwalled carbon nanotubes (MWNTs). The [email protected] foam-based devices were demonstrated to be versatile pressure sensors capable of detecting both tiny and large-scale motions.
Boost to Make in India initiative
The findings were published in the journal Applied Materials and Interfaces(ACS). Dr. Gupta has also submitted three national patents for these sensors. The technology can be used to monitor the pulse waveform of a human radial artery in real-time and is aligned with the ‘Make in India’ initiative.
The sensors have been tested for different levels of strains including micro and large-scale motion tracking and can be used in biomedical devices, skin electronics, and minimally invasive surgery. This cutting-edge technology for wearable and robotic device applications is in the third level of the Technology Readiness Level, and Dr. Gupta intends to produce a prototype for an array of sensors in the future.