Affordable PCR testing

When a problem encountered by researchers in the course of their work inspires them to develop a solution, then it value-adds to their effort.

Last year, researchers at the department of electrical engineering at IIT-Bombay, in collaboration with Strathclyde University, Glasgow, made news when they successfully developed an inexpensive sensor to detect the SARS-Cov-2 virus in wastewater. Once deployed in sewer systems in cities, the sensor serves as an early warning system of emerging outbreaks in communities. Work is currently on to finetune the technology for wider application.

While working on the sensor, the team realised that their lab had no PCR (polymerase chain reaction) test machine, which helps detect genetic material from a specific organism, like a virus. The IIT team was, thankfully, provided a portable PCR thermocycler by their collaborators in Strathclyde. It, however, got them thinking about how this basic tool for molecular sensing is out of reach for countless students, educators, and researchers in India because of its prohibitive cost.

This inspired the team to think of an affordable molecular sensing machine. Recalls Siddharth Tallur, associate professor, department of electrical engineering, IIT-Bombay, who headed the research, “My goal was to make a fully integrated system that could perform sample pre-processing, virus concentration, nucleic acid isolation and amplification, and sensing in one unit.” It would help research organisations as well as educational institutions focussed on molecular biology, genetics and engineering programmes in biosciences and biotechnology.

After two years of effort, Tallur and his team have developed the prototype of a low-cost PCR machine. It has been “lovingly named” WELPCR, since students and staff of Wadhwani Electronics Lab (WEL) in the electrical engineering department had played a big part in making it happen. The cost of components per unit is less than ₹10,000 — a fraction of the ₹4 lakh-plus needed to buy a commercially available PCR thermocycler.

Initially, the team toyed with the idea of buying and hacking a commercially available PCR thermocycler, but found that the software was proprietary and their mechanical designs unsuited for Indian conditions. Open-source PCR machine designs on the internet did not help either, since the cost of components and their availability in India posed a challenge. So, the answer was to build and design one indigenously. As Tallur says, “We took up the task of designing our own PCR machine, using components that we could purchase relatively easily through the series of lockdowns and Covid-19 restrictions in 2020 and 2021.”

The WELPCR prototype uses a Peltier cell for temperature cycling of samples and has specifications comparable to commercially available PCR machines. The unit has a touchscreen display for real-time read of live process parameters as well as built-in buttons for keying in and adjusting process setpoints.

The mechanical assembly and electronics were all designed in-house. Prototyping facilities in the department of electrical engineering at IIT-Bombay were used to manufacture the mechanical assembly using laser cutter and hand-held power tools, while PCB (printed circuit board) manufacturing was outsourced to a local vendor. Assembly and testing of the PCBs and integrated system were also performed in-house.

According to Tallur, in the absence of affordable testing equipment many students of molecular biology and bioengineering are usually shown only a demo of a PCR by lab technicians, with little or no hands-on practice. Also students undertaking microbiology, molecular biology and genetics-related projects that require amplified DNA usually get it done for a fee at diagnostic and testing labs. The WELPCR could change all that.

The IIT team needs support for producing moreWELPCR units for further testing and clinical validation. It welcomes collaborations, partnerships and sponsorship for research on DNA sensing applications. Tallur is optimistic, “If we can secure funding through CSR or philanthropic grants, we could offset costs and even provide the technology to end-users at a much lower or no price.” That would indeed be a big boon for researchers and students alike.

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