IBBME researchers develop pill-sized heating device for diagnostic testing

U of T Engineering researchers have developed a ‘heater’ — the size of a pill tablet — that regulates temperature through the different stages of diagnostic testing. This technology enables resource-limited regions around the world to perform tests for infectious diseases without the need of a large device.

This invention was published in the journal of Proceedings of the National Academy of Sciences (PNAS).

Developed by PhD candidates Buddhisha Udugama and Pranav Kadhiresan (IBBME, Donnelly Centre), under the supervision of Professor Warren Chan (IBBME, Donnelly Centre), the miniaturized heater measures just 8 millimetres in diameter.

In a typical diagnostic test for infectious pathogens, multiple temperature-regulation steps are involved. The ability to control temperature is crucial to the accuracy of the test results — this is especially important in areas where access to large research facilities are limited.

“The lack of electricity adds a layer of complexity,” says Udugama. “Our miniature heater addresses that — it can be used in various settings to detect viruses without the need for electricity. If we were to summarize the benefits of our technology, it would be accessibility, portability and precision.”

The outside of the heater tablet is composed of a non-reactive acrylic mold that encapsulates lithium, a reactive component that is commonly found in battery cells. When dissolved in water, the reactive lithium interacts with the solution to release heat and hydrogen gas. This results in an increase of temperature for an extended period of time.

The researchers observed that the reproducibility of the temperature profile is controlled by constant gas release, which is dictated by the shape of the lithium mold. After testing multiple shapes of the lithium mold – from circles to triangles – they found the star shape to be the most ideal for precise heating.

The miniature heater significantly reduces the footprint of heating. Left: typical plate heater used in the laboratory. Right: Miniature heater. (Photo: Qin Dai)

Consolidating multiple steps into a single tablet also means specialized training is not required to operate any diagnostic testing, reducing the chance of human error and making the device accessible to the public.

“The precision and flexibility that our heaters opens the door to a future of do-it-yourself diagnostic kits,” says Kadhiresan. “We could combine the simplicity of a high school chemistry set with the precision of cutting-edge lab instruments.”

Picture of the miniaturized heaters with various lithium mold shapes. (Photo: PNAS)

“Tablets are conventionally used for medications such as aspirins. But we have now developed a series of tablets and pills that can diagnose diseases,” says Chan, principal investigator on this research and director of IBBME.

“Combined with smartphone technology, everyone would have a portable system that can track, monitor and diagnose infections. This is critical for preventing the spread of diseases.”