Pill‑Sized Heater: Portable, Precise Temperature Control for Diagnostics

Engineers have developed a heater — about the size of a pill tablet — that regulates the temperature of biological samples through the different stages of diagnostic testing. This technology could enable resource-limited regions around the world to test for infectious diseases without the need for specialized training or costly lab equipment.

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 and is especially important in areas where access to large research facilities is limited. The miniature heater can be used in various settings to detect viruses without the need for electricity.

The outside of the heater tablet is composed of a non-reactive acrylic mold that encapsulates lithium, a reactive element 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 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 — the star shape, measuring 8 millimeters in diameter, was found to be the most ideal for precise heating.

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.