Indian billionaire, doctors spar over US$900 brain blood-flow tracker Temple

MUMBAI – A tiny, US$900 (S$1,150) wearable device being developed by an Indian billionaire entrepreneur and showcased by some of India’s top sportspersons has sparked criticism from doctors who say its claims of tracking blood flow to the brain are exaggerated.The Temple device is less than 2.54cm wide and weighs under 2 grams. It sticks to the side of the head between the forehead and the ear, or the temple area.Promotional materials for the device, developed by Deepinder Goyal, say its BrainFlow feature shows how well the brain is being supplied with blood in real time, and its Entropy feature can detect how hard the body works to shed heat.It can also measure thermal, immune, digestive, cognitive and emotional readings that help to transform how a person regulates their health, they say.Priced at US$907, the device comes in six colours. India’s cricket captain Shubman Gill and Olympic medal-winning badminton player P.V. Sindhu have worn it.Some well-known doctors in the country, however, are sceptical of the claims, saying the device’s capabilities are not backed by peer-reviewed research. In prime-time shows and on social media, they are calling for the device to come under the purview of medical regulators.Prominent Indian hepatologist Cyriac Philips, known as “TheLiverDoc”, has been criticising the device on his X account with 328,000 followers, calling Temple “the biggest health scam”.“People must be aware of wellness hacks such as wearables also, even though they are not marketed as health devices,” he said.On one prime-time TV discussion, paediatrician and nephrologist Sanjeev Bagai called Temple a “gimmick”, saying it has “no formal approval or clearance”.Goyal has hit back at the criticism from doctors, saying Temple is a “fitness tracker, and wellness device”, not a medical one.Indian doctor Jason Philip wrote on X that assessing blood flow to the brain is not easy, and optical signals placed over the temple skin will only give data on the “superficial temporal artery” that supplies blood to the face and skin.In a statement, Temple said BrainFlow and Entropy are new metrics “with emerging science”, and that more research will follow, adding that some metrics will eventually need regulatory approval.Scrutiny on makers of wearablesThe debate on Temple comes as wearable makers overseas also face questions on when a fitness feature becomes a medical one.Some Apple Watch features, such as hypertension notifications, have received US Food and Drug Administration (FDA) clearance as software-based medical features.In 2025, the US FDA warned Whoop, saying its wrist-worn fitness tracker’s blood-pressure feature looked like a medical one, a view the company disputes.Goyal is best known for co-founding Eternal, which houses India’s biggest listed food-delivery company Zomato and has a market value of about US$35 billion. The 43-year-old stepped down as chief executive of Eternal in 2026 to focus on Temple.Temple, which has professors from the University of Ottawa and Harvard on its advisory board, raised US$54 million in February at a valuation of about US$190 million.Goyal said Temple has received orders from more than 62 countries since Nov 1.On its website, Temple says it is also working on detecting conditions like snoring and jaw clenching. REUTERS