Today's status
Go · Caution · Recover
One warmed light with today's recommendation and the things to watch out for. You'll know what kind of day to have in two seconds.
Timing is everything.
Built on Apple Watch + Apple Health
Membrane Health reads the signals your Apple Watch already measures and computes how coherently your systems are holding together under today's load. Your result — go, caution, or recover — is measured against a mathematical definition of health, calibrated to your own physiology.
Deterministic mathematics · No black-box AI · Private through Apple Health
Your day · Free
No wall of charts. The free home screen gives you a clear read at a glance — go, caution, or recover — with the whole picture it's listening to right behind it.
Today's status
One warmed light with today's recommendation and the things to watch out for. You'll know what kind of day to have in two seconds.
Today's recommendation
Beyond the light: a short, specific recommendation for the day — plus the areas to watch out for, so the read is something you can actually act on.
Mode detection
It names the state your system is actually in — Sleep, Stress, Rest, Flow, or a rare personal peak — so the day's advice fits where you are. Meet the five modes →
Membrane Resilience
A plain snapshot of how much room sits between today's load and the edge of what your body can comfortably take.
Step up to Basic for your personalized baselines, Health Dimensions, Body Load, Raw Metrics, and insights on coherence, timing, phase, amplitude, drift & recovery.
The difference
Most health apps ask whether today looks like your recent past. Membrane Health asks a deeper question — how is your system organizing load, recovery, timing, and reserve relative to a formally defined healthy state?
Your 28-day history calibrates the measurement to you. The definition stays fixed; your position within it changes. That is the difference between a personal average and a measurement.
What it measures
Four things have to hold for a living system to stay itself under load. Membrane Health reads each one — and turns it into something you can act on today.
Boundary
The limit within which today's load can still be organized and recovered from — and how much room sits between where you are and where that edge is.
Stability
Whether your system holds its organization as conditions change — keeping its shape under load, rather than beginning to fragment.
Coherence
Whether your processes stay coordinated with one another — in time and in phase — instead of pulling apart. The quantity nothing else measures.
Recovery
How load becomes restored capacity over time — which way you're moving, and how long until you're back. See the science →
measured signals → relations through time → a bounded physiological state → today's capacity
Why "membrane"?
A cell holds its shape with a membrane — a living boundary that flexes and stretches, but only so far. Your body works the same way. There's a limit to how much you can take and still bounce back.
Stay inside it and you adapt, recover, and grow. Push past it and you break down. Membrane Health finds your edge from your own data and shows you where you stand inside it — every single day. That space between where you are and where your edge is? That's how much you've got left.
— the light you find by going in.
Timing is everything
Timing reaches into far more than clocks or schedules. It shapes whether the movements of life arrive in an order the body can actually receive, organize, and use well.
Your body isn't a set of dials with good and bad levels — it's a web of rhythms that have to stay in time with one another, and when that timing slips you often feel it before any single number looks wrong. So Membrane Health reads your timing, not just your state: the order things arrive in, the window in the day when effort will land, how many days until you're recovered, and where you are in your own cycle. Timing isn't a feature here — it's the axis everything is built around.
What's under the hood
Membrane Health doesn't infer your state — it computes it, from explicit mathematics that has been machine-checked for the properties it claims*. That stable mathematical ground is the part nothing else has: hand an AI your entire health history and, with no stable ontology to read it from, the best it can return is a plausible story. Membrane Health reads the state itself. It's read against something medicine has never had: a formal definition of health — the observable physics of health.
Two different things, kept separate: formal verification establishes the integrity of the mathematics; physiological validation establishes how its measurements behave in people — tested against real human data, and ongoing.
Real signals
Actual readings from your Apple Watch — heart-rate variability, resting heart rate, recovery, VO₂ max, sleep stages, breathing rate, wrist temperature, blood oxygen, movement — sorted into four living systems, read from your own 28-day baseline and held against a formal ontology of what it actually means to be healthy.
Explicit math
Your state comes from named, inspectable formulas — a recovery "energy," a set of tolerance bands, the measured distance between you and your edge. No neural network deciding your day, and every reading can be traced back to the numbers behind it.
Formally proven
The science is verified in Lean — the same kind of proof system used to check aerospace and cryptographic software. Over 15,000 theorems and lemmas, with no unproven assumptions at the core. One, in plain words: when your body turns strain into recovery, your health provably rises.
Want to go deeper? The whole picture — from the human idea to the mathematics to the proof — The science of Membrane Health →
* Formally proven is not a statement of physiological truth or a disease diagnosis. What it does mean: our mathematics doesn't drift or contradict itself. Our formal mathematical ontology of health is stable, structured, auditable, and fully transparent — which is exactly what makes it reliable.
The five modes
Each reading resolves your whole system into one of five modes, from deep restoration to a rare personal peak. The last two have to be earned.
Deep overnight restoration.
Elevated demand — healthy in bursts.
Recovery in progress, reserves rebuilding.
Balanced and sustainable — the zone.
A rare, earned alignment.
Flow and Nova aren't luck. The mathematics only resolves to Nova when your whole system aligns at once — deep reserve, clean across every signal, surplus to spend.
How it works
Membrane Health is built on the data your Apple Watch already collects, read straight through Apple Health. It uses your history to form a first picture of you, on day one.
It learns your real rhythm — sleep, recovery, the way your normal moves. Readings are live from the start and sharpen as it learns.
Each morning it gives you a clear read — go, caution, or recover — and shows you how it's all holding together behind it.
In closed beta since February 2026 — with its model calibrated against real human physiology.
Basic
Free gives you the honest daily call — glance and go. Basic takes that very same measurement and opens it up: your personal baselines, every system scored, the raw signals behind them, and short reads on what’s moving today.
Same math as the daily call — shown in more depth. Basic is where the reading starts to explain itself.
Plans
Every tier is the same measurement — the formal math read against your own 28-day baseline. Free is a quick glance-and-go; each tier above it opens that same reading into greater depth and detail.
Free
"What kind of day should I have?"
Basic
"What's shaping today's state?"
Pro
"How is my physiology changing over time?"
A research-grade Pro+ tier — for clinicians, coaches, and power users — is on the way.
Pro Mode
Pro is for the days you want to look under the hood — deeper trends, a live instrument panel, and a way to hand it all to someone who can help.
You'll never need to decode any of this to use the app. It's a real instrument panel — proof there's an engine here, not a vibe.
And four tools that come with Pro
A full report from your month of data — trends, outliers, and a clean PDF you can keep or send.
Hand your data to a clinician, coach, or trainer in a form they can actually read and act on.
A simple map of where you are in your body's cycle right now — and what it's ready for.
Guided audio journeys that train recovery from the inside — the one tool that doesn't just measure you, it does something for you. A growing atlas of places, each soundscape tuned to you.
One foundation, two scales
Available at launch, Membrane Health computes your whole-system state from the signals your Apple Watch already measures. The same mathematical foundation reaches a second scale — a research instrument that measures boundary response directly.
A controlled pulse of light from your phone, and a map of how distributed parts of the body respond together, in phase — phase-coherence imaging. It's patent-pending, in research and development, and like everything here, it's measurement, not diagnosis.
A preview of work in development — not yet in the app. The full research program lives on the company site — the platform at Fieldflux Biosystems →
Your data
Membrane Health is built on Apple Health — it reads the signals your Apple Watch already writes into Apple's ecosystem, with your permission. It doesn't assemble a second copy of your life on our servers to mine or resell. The reading happens on your data; the data stays yours.
Read, don't hoard
We read the metrics your watch already stores in Apple Health, right where they live — not into a parallel database of you, assembled to be monetized.
Never sold
Fieldflux does not sell your personal information, to anyone. There's no advertising business here that depends on your data leaving your hands.
Consent-driven
Hand a 28-day snapshot to a clinician or coach and it carries no name, age, sex, or contact details — and self-destructs after three days. You choose what's shared, with whom, and for how long.
Your controls
Every permission lives in Apple Health, under your control. Grant it, narrow it, or revoke it whenever you like — the app reads only what you allow.
The whole picture lives in our Privacy Policy — plainly written, and honest about the one time your data moves: a share you choose to send.
Coming soon
Membrane Health is in closed beta now, with its calibration confirmed against real human physiology. It opens to everyone on launch day.
You're on the list. Check your inbox to confirm — we'll see you on launch day.
For iPhone & Apple Watch.