Massachusetts-based Stat Health has emerged from stealth to introduce a round-the-clock in-ear wearable that measures blood flow to the head.

The aim is to understand symptoms such as dizziness, brain fog, headaches, fainting and fatigue that occur when standing.

These are common symptoms for illnesses such as long Covid, postural orthostatic tachycardia syndrome (pots), myalgic encephalomyelitis chronic fatigue syndrome (ME/CFS), and other orthostatic (caused by standing) syndromes that affect more than 13 million Americans.

Clinically tested at Johns Hopkins and peer-reviewed in Journal of the American College of Cardiology, the device has been shown to predict fainting minutes before it happens.

The company is backed by $5.1m in seed funding from J2 Ventures, BonAngels Venture Partners and a group of angel investors. The company has also received grant funding from the US Air Force.

Many people with illnesses such as long Covid, pots and ME/CFS suffer from symptoms caused by reduced blood flow to the brain upon standing. While theoretically understood, this has been difficult to prove experimentally, until now.

Doctors at Johns Hopkins, Brigham & Women’s, and Harvard Medical School have used ultrasound to demonstrate that cerebral blood flow (CBF) – ultrasound-measured flow in cerebral arteries as a method of quantifying blood flow to the head – is a key biomarker that objectively measures the presence and severity of many of these invisible illnesses.

“CBF is the critical missing vital sign,” said Peter Rowe from Johns Hopkins Medicine. “Poor CBF is the cause of common orthostatic symptoms such as dizziness and brain fog. My Dutch colleagues have measured this with ultrasound on over a thousand patients. However, it’s not easy to measure CBF, so most clinics approximate using secondary metrics of heart rate and blood pressure, which often mislead. Unfortunately, this frequently leads to the wrong conclusion that the symptoms are just psychological, when in fact there are physiological abnormalities.”

To fit into a wearable form factor, Stat uses an optical sensor instead of ultrasound and taps into a shallow ear artery to measure a proxy to ultrasound-derived CBF.

“It’s well understood that the ear is a biometric gold mine because of its close proximity to the brain and major arteries,” said Daniel Lee, CEO of Stat Health. “This allows for new biometrics such as blood flow to head and blood pressure trend* to be possible. In addition, the ear is largely isolated from data corruption caused by arm motion, a problem that plagues current wearables and prevents them from monitoring heart metrics during many daily tasks. The ear is really the ideal window into the brain and heart.”

Stat is said to be the world’s smallest wearable, half the rigid volume of Bose sleepbuds, and even smaller than some invisible-in-the-canal hearing aids. In addition to the optical sensors, the device incorporates an accelerometer, pressure sensor, temperature sensors, AI edge computing, multi-day battery life and a micro solar panel.

It can be worn in-ear round the clock and co-exists with more than 90% of devices that go in or around the ear, and can be left in while sleeping and showering. And because it can charge using solar while in-ear, some may never have to take it out to charge.

The earpiece auto-detects a user’s every stand to track how heart rate, blood pressure trend and blood flow to head change in response. It distils that into an up score to track time spent upright, and a flow score to help users pace their recovery by watching for blood flow abnormalities. It then learns about each user’s unique body over time to provide personalised coaching to promote healthy lifestyle choices, such as informed hydration and salt intake, and paced rehab.

“Nobody has realised the ear’s true potential due to the miniaturisation and complex systems design needed to make a practical and user-friendly ear wearable,” said Lee. “I’ve been pioneering ultra miniature in-ear electronics for about a decade including my work bringing Bose sleepbuds to market, and it still took us three years to figure this out. After multiple engineering breakthroughs, we’ve succeeded in unlocking the ear to combine the convenience and long-term nature of wearables with the high-fidelity nature of obtrusive clinical monitors. No other device comes close along the axes of wearability and cardiac signal quality, which is why we believe Stat is truly the world’s most advanced wearable.”

Founded in 2020, Stat Health has received more than $5.1m in financing. Founders Daniel Lee and Paul Jin previously ran Bose’s health product innovation group, and Lee was the inventor of Bose sleepbuds.

* Stat’s BP trend algorithm does not output mmHg, but instead provides a 0 to 20 trend score. It is not intended for diagnostic use and intentionally cannot be compared with diagnostic criteria such as the 130/80mmHg threshold.