Illustration explaining how the device works. Credit: Dalchand Ahirwar

A low-cost, sensitive device can detect early signs of stroke in which a blood clot in an artery disrupts blood flow to the brain1. It is an alternative point-of-care solution for diagnosing stroke, well before it becomes severe.

This device could potentially be used to reduce the number of deaths caused by strokes, says a team at the Indian Institute of Technology Mandi, in Himachal Pradesh. MRI and CT scans detect signs of strokes, but these techniques are expensive. To find a cheaper alternative, the scientists designed the device, that has a light emitting diode (LED), a photodiode and a microcontroller unit. The LED emits near-infrared light which interacts with oxygenated and deoxygenated blood by penetrating the tissue up to few centimetres.

The photodiode collects reflected light from the tissue and sends it to a microcontroller which converts analogue signals into digital signals, which are then displayed on a laptop or a mobile phone as readable signals for biomarkers of stroke.

The team, which included Shubhajit Roy Chowdhury and Dheeraj Khurana, mimicked stroke-forming ischaemic conditions on the forearm and the frontal lobe of an adult brain.

In all ischaemic conditions, the device detected biomarkers such as regional oxygen saturation and regional muscle oxygen consumption which decreased due to lack of oxygen-bound haemoglobin.

The biomarker regional blood volume index increased because of an increase in deoxygenated haemoglobin. The researchers say this reflects the dynamics of haemoglobin, which can help identify abnormal blood flow conditions at a local tissue.