The technology behind Cira
Your phone camera reads clinical vitals. Independently validated.
Cira's 30-second face scan captures 30+ health markers — heart rate, blood pressure, HRV, stress, and more — using your phone camera and nothing else. The technology is peer-reviewed, used by Allianz and Deutsche Telekom, and runs entirely on your device.
HR mean error vs ECG
0.13 bpm
Frontiers in Physiology, 2025
The short version
If you only read three things.
How it works
A 30-second face scan reads micro-changes in skin color (rPPG) and tiny head movements from your heartbeat (rBCG). AI analyzes both signals to extract clinical vitals — no contact, no wearable, no hardware required.
How accurate it is
Heart rate accuracy of 0.13 bpm mean error (peer-reviewed, Frontiers in Physiology, 2025). A clinical ECG and a Cira scan typically agree within 1 beat per minute.
How private it is
All processing happens on your device. Your video is never uploaded, never stored, never sent to a server. We only receive the final vitals — not your face.
Why we partnered with Shen AI
Cira is a triage tool. We let the experts handle the scan.
Building clinically-validated face scan technology takes years of computer vision research, terabytes of training data, and rigorous medical validation. That's not what Cira is for. Cira is for helping you decide what to do when you don't feel right.
So we partnered with Shen AI — the company that does build that technology, and is one of the global leaders in camera-based health monitoring.
Founded by serial entrepreneurs
Estonian company founded in 2020 by Remi Koscielny (CEO, took Vivid Games public) and Przemek Jaworski (CTO, founded Zmorph). The team includes researchers, computer vision engineers, and medical scientists.
Trusted by global leaders
In production with 60+ partners across 33 countries — including Allianz, Deutsche Telekom, Aster DM Healthcare, and Heartery, the #1 BP app on the Apple App Store in US, UK, Canada and Australia.
Peer-reviewed by independent scientists
Validated in Frontiers in Physiology (Sept 2025) by the Polish Academy of Sciences and Wroclaw Medical University — mean absolute error of just 0.1 bpm vs clinical ECG.
Trusted by
How the science works
Two technologies. One scan.
Most face-based health AI uses one signal. Shen AI combines two — which is why it works reliably across all skin tones and even in less-than-ideal lighting.
Signal 1
rPPG: Reading blood flow from skin color
Every heartbeat pushes a wave of blood through vessels just under your skin. That changes the way your skin reflects light — by tiny amounts the human eye can't see, but a camera can.
This is remote photoplethysmography (rPPG) — the same physics behind hospital pulse oximeters, applied through a regular phone camera.
Signal 2
rBCG: Reading micro-movements from your heartbeat
Each time your heart contracts, it produces a tiny mechanical movement in your head — far too small to see, but visible to a camera tracking your face frame by frame.
Combining rBCG with rPPG gives a more reliable signal — especially in low light or for darker skin tones, where rPPG alone can be less accurate.
Together, the two signals are processed by Shen AI's Multisensing Engine — the AI that turns raw camera data into clinical vitals.
How accurate is it?
Validated against clinical-grade equipment.
For context: in the 2025 Frontiers in Physiology study, Shen AI's heart rate estimates typically differed from clinical ECG by 1 bpm or less when averaged over 60 seconds, with a strong correlation to ECG (r > 0.99) across the study sample. Individual results can vary with lighting, skin tone, motion, and device quality.
Read the full peer-reviewed studyImportant. Cira presents these vitals as triage signals to inform our recommendations — not as medical diagnoses. The technology is currently undergoing EU Medical Device Regulation (MDR) conformity assessment. Not for emergencies — if you're experiencing a medical emergency, call your local emergency number immediately. For more on what Cira is and isn't, see our How It Works page.
What Cira measures
30+ health markers from one 30-second scan.
Vital Signs
Measured directly from the face scan
- Heart Rate
- Heart Rate Variability (HRV)
- Blood Pressure Estimate (Systolic + Diastolic)
- Cardiac Workload
- Breathing Rate
- Stress Index
- Parasympathetic Activity
- Body Mass Index
- SpO₂ (under research)
- HbA1c (under research)
- Hemoglobin (under research)
Health Indices
Face scan + your basic info
- Vascular Age
- Wellness Score
- Waist-to-Height Ratio
- Body Fat Percentage
- Basal Metabolic Rate
- Body Shape Index
- Conicity Index
- Body Roundness Index
- Total Daily Energy Expenditure
Cardiovascular & Metabolic Risks
Face scan + your basic info
- Cardiovascular Risk Score
- ASCVD Risk
- Coronary Heart Disease Risk
- Stroke Risk
- Heart Failure Risk
- Peripheral Vascular Disease Risk
- Coronary Death Risk
- Cardiovascular Event Risk
- Diabetes Risk
- Hypertension Risk
- Fatty Liver Disease Risk
All risk indices are calculated using established clinical models, including the Framingham Heart Study and 2024 European Society of Cardiology guidelines. Risk scores are population-based estimates, not individual diagnoses.
Privacy
Your face never leaves your phone.
Most face-based AI sends your video to a server, runs analysis there, and stores the data. Shen AI doesn't.
The entire scan runs on your device — in your browser or your phone — in real time. Your video is never uploaded, never stored, never sent anywhere. Cira only receives the final vitals data, not the raw video.
On-device
Your video stays on your phone.
No cloud, no storage
Nothing sent or kept.
GDPR compliant
Built for EU privacy.
Real-world results
What happens when this technology meets a product.
Case study · Heartery
#1 blood pressure app in 4 countries
Heartery is a hypertension management app. After integrating Shen AI's face scan technology, they became the #1 blood pressure app on the Apple App Store in the US, UK, Canada, and Australia. They report a 350% increase in user retention, and an average blood pressure reduction of 2.5–3 mmHg among users.
Case study · Dr.Digital
A virtual clinic without the hardware
Dr.Digital used to ship physical blood pressure cuffs and other devices to its patients. After integrating Shen AI, they removed the logistics of distributing hardware and scaled preventive care across their entire patient base — using only the phones their patients already had.
"Integrating Shen AI into our platform helped us scale preventive care without the operational burden of distributing and managing medical devices. That's a game-changer for a virtual clinic like ours."
From vitals to answer
Reading vitals is just the start. Cira tells you what to do.
Most camera-based health technologies stop at giving you a number. Cira goes further. Once Shen AI delivers your vitals, our AI assistant — powered by Anthropic's Claude — combines that objective data with your answers to a few targeted questions about how you're feeling.
Self-care at home
With clear notes on what to watch for.
Monitor and recheck
Re-scan in a few hours and compare.
See a doctor
Book one in 30 seconds via Air Doctor.
Seek urgent care
Calm, immediate steps to get help now.
Plus a structured visit summary you can email to any doctor, anywhere.
For the technically curious
Want to dig deeper?
Read the peer-reviewed validation study
Pstras et al., Frontiers in Physiology, September 2025.
See Shen AI's technology page
Detailed technical documentation on rPPG, rBCG, and the Multisensing Engine.
Try Shen AI's own demo
Test the underlying scan technology directly on Shen AI's site.
Real vitals. Real science. Real answers.
No hardware required. Your first scan is free. No credit card. No app to install.
Start your scan