No more finger pricks, IISC invents painless way to check blood sugar

Millions of diabetic patients who rely on invasive methods involving needle pricks to check their blood sugar levels may soon experience relief from pain. Researchers at the Indian Institute of Science (IISc) have developed a painless technique to measure glucose levels.

Photoacoustic sensing

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It’s a non-invasive technique that uses laser beams to measure glucose in biological tissues

A laser is projected onto skin which absorbs light, generating sound waves through vibrations

Waves are then detected by sensors, enabling accurate measurements without pain

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Jaya Prakash, Assistant Professor at IISc’s Department of Instrumentation and Applied Physics, explained that diabetic patients often needed to test their glucose levels multiple times a day. “Repeated use of needles is not only inconvenient but also poses a risk of infections. To address this, our team has introduced a novel method called photoacoustic sensing, which uses laser beams to measure glucose levels,” she said.

Photoacoustic sensing involves the generation of sound waves when skin absorbs light. In this technique, a laser beam is projected onto the skin, where it is absorbed. The tissue expands due to the absorption of light, creating vibrations which are then picked by sensors. Glucose changes the intensity of these sound waves, allowing them to measure blood sugar levels accurately.

The intensity of the sound waves allows the researchers to estimate the concentration of glucose. Moreover, this procedure does not damage the skin.

“When a laser beam is shined on biological tissue (the outer layer of the skin), the tissue absorbs the light and heats up slightly. This causes the tissue to expand and contract, creating vibrations which can be picked up as ultrasonic sound waves by sensitive detectors. Importantly, this process does not harm the tissue,” Prakash explained.

The researchers successfully estimated glucose concentrations in water, serum solutions and animal tissue slices with near-clinical accuracy. They also demonstrated the ability to measure glucose levels at various tissue depths.

“If we know the speed of sound in this tissue, we can use the time series data to map our acoustic signals to the depth at which they are coming from. Since sound waves don’t scatter much inside tissue, the researchers were able to get accurate measurements at various tissue depths,” said Swathi Padmanabhan, a PhD student at the IISc.

The team conducted a pilot study using the sensor setup to track blood glucose levels in a healthy participant before and after meals over three days.  “Finding the right setup to do this experiment was very challenging. Currently, the laser source we use has to generate very small nanosecond pulses, so it is expensive and bulky. We need to make it more compact to put it to clinical use. My lab mates have already started work on this,” added Padmanabhan.