Medical devices & diagnostics · Stroke detection
Zeit Medical
A soft EEG headband built to notice a stroke while its wearer is asleep and raise the alarm before anyone else can. Five years after its seed round it has a registered study, two published patent applications and no FDA authorization.
The hours nobody was working on
A stroke does not hurt. There is no clutch at the chest, no warning ache. Someone in the United States has one every 40 seconds, by figures Advocate Health cites, and the ones that begin at two in the morning are close to invisible. The person finds out at seven, trying to stand up. By then the clot-dissolving drug and the catheter that could have pulled the clot out are off the table.
Orestis Vardoulis and Urs Naber named the company after the thing that gets wasted. Zeit is German for time.
“It used to be that you couldn’t do anything, but suddenly it really mattered how fast you got to the hospital,” Naber told TechCrunch in 2021. Millions have gone into shortening the ambulance ride and the door-to-needle time, he said, and nobody was working on the hours before the 911 call.
Their answer is a fabric headband with electrodes, worn overnight and paired to a phone. A model watches the EEG trace. If it sees the pattern it wakes the wearer, pings the caregivers on the list, and can call 911 on its own.
What the operating room taught them
The clinical premise is not exotic. Neurophysiologists already read EEG during carotid and cardiac surgery and watch ischemia arrive in the trace. That is where the training data came from.
“There are specific patterns that people are trained to catch with their eyes. We learned from the best neurologists out there how they process this data visually, and we built a tool to detect that automatically,” Vardoulis said in the same interview. Most of the data analyzed at that point came out of the operating room, where the answer can be checked against imaging the same day.
That origin is written into the company’s own trial registration. The ZASH protocol says the labeled home data will be used to further develop what it calls the existing operating room based stroke detection algorithm and adjust it for outpatient use. The model was born in a setting where a patient lies still under anesthesia with a technician watching. The home is a different problem, and the company’s patent filing lists what it has to survive there: medication status, sleep state, migraine, seizure, post-ictal states and other stroke mimics.
Asked on Hacker News in 2021 about the false positive rate, the founders answered: “We are optimizing our tools for zero false positives. Final product requirements will be set in communication with the FDA.” Five years on, no published number exists.
An engineer and an intensivist
Vardoulis grew up in Greece wanting to design aircraft, studied mechanical engineering at Thessaloniki, and wrote a doctoral thesis on non-invasive hemodynamic monitoring at EPFL in Switzerland. A Swiss grant carried him to Stanford, first into flexible electronics, then into the Biodesign Innovation Fellowship in 2017. Fifteen of his papers are indexed in PubMed. All predate Zeit, and none are about EEG.
Naber is a pediatric critical care physician trained at Dartmouth and Stanford who had already tried and failed at a needle-free vein access company during residency. The two met in the fellowship, where the clinical focus that year was orthopedics. On a visit to a rehabilitation center they watched a patient being treated for stroke-related imbalance, and started asking why the good treatments arrive too late.
Zeit went through Y Combinator in Summer 2021 and closed an oversubscribed $2 million seed that October, co-led by SeedtoB Capital and Digilife. Vardoulis became a Ferolyn Fellow the same season.
The timeline, and where it stops
In August 2021 the company said it was preparing to go commercial in 2023, on prescription, at a reported $35 a month. In December 2022 it registered ZASH, a feasibility study of 300 people who had just had an ischemic stroke, each wearing the headband for 90 nights. In September 2023 Advocate Lutheran General in Illinois and Aurora St. Luke’s in Wisconsin announced they were the first sites in their states.
Then the public record thins. The ZASH entry has not been updated since December 19, 2022 and still reads unknown. The last company blog post is from April 2024, the last post on X from March 2024. Two patent applications were published in May 2025, naming Vardoulis, Naber and Stylianos Kyriacou. The website is still up and still carries the line “Zeit Medical receives FDA breakthrough designation for its at-home stroke alert technology”. LinkedIn lists two to ten employees.
What is proven, and what is still claimed
| Evidence | What the record shows | Source type |
|---|---|---|
| FDA marketing authorization | No 510(k), PMA, De Novo or registration listing for Zeit Medical appears in openFDA as of September 2026. The Halo Alert System is investigational. Nothing about it is FDA cleared or approved. | Public record |
| Breakthrough Device designation | Reported by TechCrunch in 2021 and by Neuro Rehab Times, and stated on the company website. It cannot be confirmed in any FDA database: the agency does not disclose designations before authorization, and lists them only once a device is authorized. Zeit is not on that list. | Independent |
| ZASH study, as registered | First posted Dec 30, 2022. Single-arm observational feasibility study, 300 planned, enrollment within two weeks of a confirmed ischemic stroke, 90 nights of wear. Primary outcome is feasibility of collecting EEG for algorithm development, not detection accuracy. Primary completion estimated June 2024. Status unknown since Dec 2022. | Public record |
| ZASH study, as announced | Advocate Health said in September 2023 that two of its hospitals had joined as the first sites in Illinois and Wisconsin. The registry lists no sites and no investigator, and was never updated. | Differs from registry |
| Published clinical evidence | No peer-reviewed paper on the Halo Alert System or the algorithm was found in PubMed in September 2026. No results posted to the registry. | Not found |
| Intellectual property | Two US applications published in 2025: Stroke Monitor (2025/0169768), filed May 30, 2023 with priority to a May 2022 provisional, and EEG Signal Detecting Headband (2025/0160715), filed Nov 19, 2024. Applications, not grants. No granted patent names Zeit Medical. | Public record |
| Federal funding | No NIH award in RePORTER and no matching NSF award found. | Not found |
| Commercial availability | A 2023 launch on prescription at about $35 a month was described in 2021 reporting. No evidence of a sale, a customer or revenue. | Not found |
Read plainly: the clinical logic is sound and the founders are credible, but the evidence base sits where it did in 2021. What exists is an algorithm trained largely on operating room EEG, a feasibility study built to collect home data rather than measure accuracy, and a designation that confers attention rather than proof. Missing publicly: a sensitivity figure, a false positive rate, a paper, a trial result, an FDA submission. For a device whose failure mode is a missed stroke or an ambulance sent to someone who is fine, those are the numbers that matter.
What to watch
- Any update to NCT05669456. An entry left at unknown for nearly four years is either a finished study nobody reported or one that stalled.
- A first FDA submission appearing in openFDA. A breakthrough designation only pays off once a marketing submission is filed.
- A published sensitivity and false positive rate at home, measured against imaging.
- New capital. The last disclosed financing was the October 2021 seed, and no Form D has ever been filed.
- Whether the hospital market moves first. Rivals with cleared EEG systems are selling into emergency departments while this one waits.
In their words
“It used to be that you couldn’t do anything, but suddenly it really mattered how fast you got to the hospital.”
Urs Naber, co-founder, TechCrunch, 2021 · Independent
“There are specific patterns that people are trained to catch with their eyes. We learned from the best neurologists out there how they process this data visually, and we built a tool to detect that automatically.”
Orestis Vardoulis, co-founder and CEO, TechCrunch, 2021 · Independent
“We are optimizing our tools for zero false positives. Final product requirements will be set in communication with the FDA.”
Zeit Medical founders, Hacker News launch thread, 2021 · Company-stated
“Yet because strokes cause no pain, can be difficult to identify and often happen while sleeping, the longest delays to treatment occur before a patient ever calls 911.”
Demetrius Lopes, MD, neurosurgeon and site principal investigator, Advocate Health, 2023 · Independent
“But if researchers can develop new technologies that automatically alert patients when they are having a stroke, we can take the burden of self-assessment off of our patients and hopefully provide faster treatment.”
Melissa Kadar, Advocate Aurora Research Institute, 2023 · Independent
“We really do see this as the missing puzzle piece in the stroke care continuum.”
Orestis Vardoulis, TechCrunch, 2021 · Independent
Related companies
Sources
- Public recordClinicalTrials.gov NCT05669456, Zeit Alert for Stroke at Home (ZASH)
- Public recordopenFDA 510(k), PMA and device registration queries for Zeit Medical, no matches
- Public recordBreakthrough Devices Program, disclosure policy and designation count
- Public recordUS patent applications 2025/0169768 A1 and 2025/0160715 A1
- Public recordDenali Capital Acquisition Corp. DEF 14A, director biographies
- Public recordSEC EDGAR searches, no Form D under Zeit Medical
- Public recordNIH RePORTER and PubMed searches, no awards and no papers
- Public recordFDA 510(k) K242306 and K251726, Forest Devices SignalNED System
- IndependentZeit’s early warning wearable for sleep strokes could save hours and lives
- IndependentZeit secures $2M in seed funding for its stroke-detecting wearable
- InterviewInterview with Orestis Vardoulis, Ph.D., Ferolyn Fellow
- IndependentStudy investigates whether headband device can detect strokes
- CompanyZeit Medical Announces $2m Seed Round
- CompanyZeit Medical home and team pages, and the launch thread on Hacker News
Profile researched and written by Healthcare Discovery. Last updated September 29, 2026.
