From skin to curve, every 5 seconds.
P20 turns temperature from a number you go get into a stream that comes to you. Here's the path a reading takes.
1 · Apply
The 2g sensor sticks under the armpit with a hypoallergenic medical patch. Correct placement takes under a minute and holds for days.
2 · Sense
A calibrated thermistor samples axillary temperature every 5 seconds at 0.01°C resolution, with clinically validated ±0.2°C accuracy.
3 · Transmit
Readings stream over low-energy Bluetooth to whichever receiver fits the setting: the companion app, the bedside terminal, or a ward gateway.
4 · Watch & alert
The receiving device builds the live curve, applies your alert threshold, and notifies the moment it's crossed — phone push, terminal alarm, or nurse console.
What makes continuous temperature measurement accurate
Individually calibrated sensors
Every unit is calibrated against reference standards before leaving the line — accuracy is a manufacturing step, not a spec-sheet claim.
Axillary site, continuous context
Underarm measurement is gentle and stable for long wear, and continuous sampling smooths out the position sensitivity that makes single spot-checks unreliable.
500M+ readings of real-world tuning
Alert logic like kick-blanket detection is trained on the RESYS platform's half-billion real-world data points, not lab assumptions.
Seven days of continuous monitoring on one coin cell
The whole pipeline is engineered for a CR1225 coin battery to last a full week of 5-second sampling — a fever episode, a post-op recovery window, or a BBT cycle segment on a single battery.
The engineering behind a smart wearable thermometer
Why axillary temperature sensor placement was chosen
Ear and forehead readings are fast but sensitive to positioning, ambient airflow and technique — which is fine for a single spot-check but produces inconsistent results if you tried to wear one continuously. An axillary temperature sensor placement under the arm is gentler and more stable for multi-day wear, and continuous sampling further smooths out the small variations that would otherwise show up between individual manual readings taken by different people.
How Bluetooth thermometer connectivity handles three different receivers
The sensor doesn't decide who's watching — it broadcasts readings over low-energy Bluetooth to whatever is listening: the companion app on a phone, a bedside terminal, or a ward gateway feeding a nurse console. This is a deliberate architecture choice so the same physical sensor supports a parent's phone and a hospital's monitoring dashboard without any hardware difference between the two use cases.
What actually determines continuous measurement accuracy
Sensor accuracy isn't a single spec — it's the result of calibrating each individual unit against reference standards before it ships, rather than sampling a batch and assuming consistency. Combined with 0.01°C resolution and 5-second sampling, this is what allows P20 to hold ±0.2°C clinically validated accuracy over days of continuous wear rather than just at the moment it left the factory.
Why the battery lasts a week, not a day
Continuous 5-second sampling and constant Bluetooth transmission are both power-hungry by wearable standards, so the whole pipeline — sensor, radio and firmware — is engineered specifically to stretch a single CR1225 coin battery across roughly 7 days. That duration is not arbitrary: it's built to cover a typical fever episode, a post-operative recovery window, or a multi-night segment of a BBT cycle without needing a battery change partway through.
How a wearable thermometer works — your questions
How does a wearable thermometer measure temperature continuously?
A calibrated thermistor under the arm samples temperature every 5 seconds and transmits each reading over Bluetooth Low Energy to a receiving device — the app, a bedside terminal, or a ward gateway — which builds a continuous curve rather than a single value.
Why is the sensor worn under the arm instead of in the ear?
Axillary (underarm) placement is comfortable and stable for continuous multi-day wear, whereas ear and forehead methods are optimised for a single fast reading and are more sensitive to technique and positioning if repeated.
What gives P20 its ±0.2°C accuracy?
Each sensor is individually calibrated against reference standards during manufacturing, combined with 0.01°C measurement resolution. Accuracy is validated clinically rather than estimated from a datasheet.
Does the sensor need to be paired with a specific app to work?
No single receiver is required — the sensor broadcasts over Bluetooth to whichever device is set up to receive it: the companion app, the bedside terminal, or a facility gateway, depending on the deployment.
How long does the battery last during continuous 5-second sampling?
Up to 7 days on a single CR1225 coin battery, engineered specifically to support continuous sampling and Bluetooth transmission across a full week without a battery change.