Temple wearable faces medical scrutiny over unverified brain-flow claims
Deepinder Goyal's forehead-worn device, priced at Rs 85,000, has drawn criticism from doctors who question the scientific basis of its claimed brain-blood-flow metrics, while the founder defends its fitness-tracker status and cites pending validation.
A wearable device developed by Temple, the startup founded by former Zomato executive Deepinder Goyal, has come under scrutiny from medical professionals after it launched for pre-orders in India on November 1 at a price of Rs 85,000. Critics, including hepatologist Dr Cyriac Abby Philips, have challenged the company's claims that the device can reliably measure brain blood flow and provide longevity insights.
Temple’s technology relies on optical sensors placed near the temporal artery on the forehead and generates two proprietary scores: BrainFlow, which is intended to reflect changes in cerebral circulation, and Entropy, a metric the company says indicates overall physiological workload. The firm has released two pre-print studies suggesting that BrainFlow correlates with brain-specific blood-volume changes, but these reports have not yet undergone peer review or independent replication.
Doctors argue that the superficial temporal artery primarily supplies the scalp and face, not the brain, and that variations in scalp blood flow may not represent intracranial circulation. They note that established brain-blood-flow measurements typically involve internal carotid or vertebral arteries, raising doubts about the wearable’s anatomical basis.
Goyal responded on the social platform X, emphasizing that Temple is marketed as a fitness and wellness device rather than a medical instrument and that its metrics await clinical validation. He highlighted the company’s $30 million investment, including $20 million of his own funds, and pointed to a 14-day return policy as protection for consumers. Goyal also offered to loan devices to qualified researchers for independent testing and cited a pre-print comparison with near-infrared spectroscopy that showed a correlation of 0.91 with brain signals versus 0.49 with scalp signals.
The founder reiterated that Temple makes no diagnostic or disease-prevention claims and that regulatory clearances will be obtained before any such claims are made. He described Entropy as the product’s primary focus and said the company aims to compete globally, with India expected to represent a small share of sales. Goyal apologized for generalizing Indian doctors in earlier comments and invited users to evaluate the device based on forthcoming user reviews and scientific validation.