PremiumThe controversy surrounding Deepinder Goyal’s Temple device raises a larger question about the science behind wearable health technology. Neurologists explain why measuring cerebral blood flow is more complicated than it appears.Deepinder Goyal sports the Temple wearable during a podcast. (YouTube/Raj Shamani)7 min readNew DelhiNov 12, 2026 06:37 AM IST First published on: Nov 12, 2026 at 06:30 AM ISTZomato founder Deepinder Goyal’s latest venture, a wearable device, has triggered a debate over how accurately technology can measure what happens inside the human brain. Called Temple, the device claims to track cerebral blood flow through a feature called BrainFlow, intended to show how factors such as exercise, sleep and meditation affect circulation.But hepatologist Dr Cyriac Abby Philips, popularly known as The Liver Doc, says there has been no clinical trial and has questioned whether a sensor placed against the skin can reliably distinguish blood flowing inside the brain from circulation in the scalp. ShareWhatsapptwitterFacebook