Temple 1st Validation Study: Deepinder Goyal Shares Brain Flow Validation Study of Wearable Health Device

Deepinder Goyal has announced the first validation study for Temple, the forehead-worn wearable developed by his healthtech startup. The study tested the device’s Brain Flow index against Transcranial Doppler ultrasound, the established clinical method for measuring cerebrovascular function.

Researchers examined 23 healthy adults under two conditions: cycling exercise and a shift from standing to lying down. The paper has been posted as a preprint and submitted for peer review. PV Sindhu Spotted Wearing AI-Powered Temple Device: What Is It and What Does It Monitor?.

Deepinder Goyal Shares Temple Brain Flow Validation Study 

Temple's first validation study is out.

Researchers tested Temple's Brain Flow index head-to-head against Transcranial Doppler (TCD), the gold standard for measuring cerebrovascular function. 23 healthy adults, two challenges: cycling and a standing-to-supine postural shift.… pic.twitter.com/LKFT5MWp4W

— Deepinder Goyal (@deepigoyal) September 7, 2026

Temple Brain Flow Study Results

Across both challenges the Brain Flow index tracked middle cerebral artery velocity with a within-subject temporal correlation of approximately 0.8. The result was statistically significant.

One finding stood out. When participants lay down, heart rate fell while brain blood flow rose. Temple recorded the rise in brain blood flow in line with the Doppler readings. Devices that rely only on heart rate would have misinterpreted the change.

The study involved healthy adults only and two specific interventions. Goyal described it as an initial step rather than a complete clinical validation.

Further Temple Validation Work Planned

Additional studies examining Brain Flow and the company’s Entropy metric are already under way in different locations. Goyal said the team will continue to publish results as they become available.

He invited independent researchers to replicate the work and offered to lend Temple devices to qualified investigators who wish to test the metrics themselves.

Background on Temple Wearable Device

Temple sits on the side of the forehead and aims to provide continuous, non-invasive signals related to cerebral blood flow and a proprietary recovery metric called Entropy. The startup has been developing the device as a tool for tracking physiological responses during everyday activity, exercise and rest. Temple Device in Small Size: Deepinder Goyal Unveils Limited Edition Temple Wearable With Enhanced Performance; Pre-Orders Will Begin Soon.

The latest study provides the first published comparison against a recognised medical reference standard. Further research in broader populations and with complementary measurement methods will be needed to determine the wider usefulness of the Brain Flow index.