Three premier Indian technology institutions – IIT Bombay, Gauhati University and the Gandhinagar-based Dhirumbhai Ambani Institute of Information and Communication Technology – have joined hands to develop high-tech sensors for use in agriculture.

The use of sensors in agriculture is not entirely new. These tiny products, placed under the soil, detect parameters such as moisture and temperature and help fine-tune inputs for higher produce. Bosch, for example, has a suite of products for this purpose.

However, the sensors developed by the three institutions is more hi-tech and can be hooked on to compatible with Internet-of-Things (IoT). They feature ‘ultra-small graphene particles’, made from graphene quantum dots, which are nano-sized fragments of graphene. Graphene, by the way, is a material made of Carbon, where the Carbon atoms are arranged as a honey-comb sheet. The arrangement of atoms imparts the material a few fantastic properties—graphene has been described to be “harder than diamond but more elastic than rubber, tougher than steel, but lighter than aluminium.”

Graphene quantum dots are disc-shaped materials made of a few layers of graphene, measuring mere nanometers; they have been scoped for a variety of sensing applications. Synthesising graphene dots, however, is not easy.

The project was funded by the Department of Science and Technology, Government of India, the University Grants Commission, the Assam Science Technology and Environmental Council.

Graphene quantum dots

Researchers engaged with the project managed to produce graphene quantum dots of the size of about 3-5 nano meters from graphene oxide. Doing this involved a lot of scientific jiggery-poggery, such as coating graphene oxide onto a carbon electrode, placing it in an electrolyte and passing current through the set up. In the end, they got their graphene quantum dots and with it they made sensors, each no bigger than a grain of lentil. These sensors are purposed for measuring the moisture content in the soil, which is said to be the most critical parameter in agriculture.

How the sensors work is another subject by itself—the more the moisture the less they are resistant to current—but suffice to say that they give a reading in three minutes and are good to be used again after 20 seconds. The researchers have checked out the stability of the product by using it continuously for nearly six months. The sensors gave consistent reading throughout the period and was found suitable for a range of soil water levels.

Now that the product is ready, the researchers are rubbing their palms for “copious field testing”, Hemen Kumar Kalita, one of the researchers, told Business Line . Dr Kalita is an Assistant Professor of Physics a the Gauhati University.

Replying to an email, Kalita said that when produced on a commercial scale, these sensors would be very affordable to farmers—about Rs 1,500 apiece.

Asked how these sensors compare with those already in the market (such as Bosch’s), Kalita said they were better both in terms of accuracy and costs and could be interfaced with IoT “which makes this product technically more valuable.”

In terms of ‘Technology readiness level” (or TRL, which is measured on a scale of 1 to 10, ten being market-ready,) Kalita said the product was at TRL-7. “We will perform copies field testing to ensure reliability and stability of the product,” he said.

The institutions intend to license the technology to start-ups.