It reads the whole system
Not one metric — your entire baseline. Heart, sleep, breath, metabolism and movement, read together into a single live state instead of a lone number.
Timing is everything.
Built on Apple Watch + Apple Health
Health was never one number — it's a whole system staying in time with itself. Membrane Health listens to all of it at once, like a conductor hearing every instrument: what's in tune, where the timing is slipping, how it's holding together. Then it tells you, live, what today is for — go, caution, or recover. From the data your Apple Watch already collects.
What it does
A single number can't hold a living state. Membrane Health doesn't try to — it reads your whole system at once, on a stable mathematical ground that lets it see what nothing else can.
Not one metric — your entire baseline. Heart, sleep, breath, metabolism and movement, read together into a single live state instead of a lone number.
Over a rolling 28 days it builds a picture of your body and measures each day against it — your body compared to your body, not to an average — held against a formal ontology of what it actually means to be healthy.
A stable, formally-verified ontology for a living system. Every reading is computed and can show its work — nothing inferred, nothing guessed. See the science →
Coherence, phase, timing, recovery, amplitude, drift — real, defined quantities that only become measurable once you have the mathematics underneath. No other health app has it.
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 formally proven correct*. 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 physics of health, not the biology of disease.
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. Nearly 6,000 theorems, with no unproven assumptions at the core. One, in plain words: when your body turns strain into recovery, your health provably rises.
* 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.
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 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 restoration. Overnight, the body clears, repairs, and rebalances — its most powerful recovery tool.
Elevated demand. Healthy in bursts — it's how we grow — but sustained without recovery, it depletes you.
Recovery in progress. Low load, reserves rebuilding — the body quietly putting headroom back.
The Goldilocks zone — balanced and sustainable, reserves intact and nothing overheating. Where most of life goes well.
A rare alignment — deep reserve, no deficit anywhere, and surplus on top, every system clean at once. Reaching it, and holding it, is a genuine feat of attention.
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.
Pro Mode
Everything above is free. 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.
Plans
Free
Your honest daily read
Basic
More of the picture
Pro
The instrument & the tools
A research-grade Pro+ tier — for clinicians, coaches, and power users — is on the way.
The road ahead
The daily read you get today sits on top of a deeper research program. Its question is the same one the whole app is built around: not how high your numbers are, but how well your body keeps time with itself.
We're building a research-grade instrument that measures exactly that — a controlled pulse of light from your phone, and a map of how distributed parts of the body respond together, in phase. It's called phase-coherence imaging. It's patent-pending, and like everything here, it's measurement, not diagnosis.
A preview of work in development — not yet in the app. When it's ready, your phone will see something no wearable can.
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.