Recovery sensing,
under the watch you already own.

Dimple is a prototype in development. It is designed to sit between your wrist and your current watch and record pulse, skin temperature and motion overnight. No second device on your wrist, no subscription planned.

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Render of the Dimple case v0.2 from CAD: zirconia shell, sapphire sensor bump and four gold contacts

30 mm across. About 2.9 mm at the edge. Designed to disappear under a watch.

30mm: diameter
~2.9mm: edge thickness, CAD
0 subscriptions: planned

Thickness is from the case v0.2 CAD (2.855 mm nominal). A worst-case tolerance stack still interferes, so it may grow. Nothing has been built or worn yet.

Designed to read three things.

PulseOptical PPG with green LEDs and a photodiode, through a sapphire bump.
Skin temperatureA digital temperature sensor on the skin side.
MotionA 3-axis accelerometer, for rest and movement.
Bluetooth LETo the Dimple iPhone app. Standard heart rate for Strava, Zwift and watches is planned, not built.

Prototype, not a medical device. Dimple makes no accuracy claims, and there is no SpO2 and no ECG. Heart rate from the pod has not been demonstrated yet.

Positioning

Not another thing on your wrist.

Works under your watchKeep the watch you like. Screenless recovery bands such as WHOOP and Oura replace it or add a second strap or ring.
No subscriptionThe plan is a one-time purchase. WHOOP sells recovery as a membership.
Open standardsPlanned: standard BLE heart rate, so Strava, Zwift and your watch can read it. HIYD is the closest rival and also targets under-watch use.

Inside

Five layers in a sealed case.

A zirconia ceramic shell with three sapphire lenses, a four-layer main board, an optical flex, a 40 mAh cell and a thin metal lid. Rendered from the project CAD. Concept stage.

Zirconia shell Sapphire sensor bump, four gold contacts
Optical flex Green LEDs, photodiode, temperature
Main board nRF52840 Bluetooth LE, accelerometer
Cell 40 mAh
Metal lid Faces the watch

Exploded view of the five layers of the Dimple pod

Render of the case v0.2 parts separated: lid, shell and sensor lenses

Materials

Ceramic, sapphire, metal.

The v0.2 case is designed as a zirconia shell, a 316L lid and sapphire lenses over the sensor. It is designed in CAD only and has not been quoted or made. A carbon fibre lid is an optional cosmetic edition under study. It would not change function.

Charging is through a small dock with four contacts. The dock board and the phone app are in development. The app has only been run against a simulated pod.

Status

Honest status: electronics, case and dock are designed and checked in CAD. Firmware builds and is simulated. The iPhone app runs in the simulator. Nothing has been built, powered or worn on a person yet.

Early access

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