The GSR Sensor we used to measure stress (arousal really)
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live skin conductance during a Glow session: stress rises, then settles back to calm
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One of the calming games Glowy supports
GIF
One of the calming games Glowy supports

Inspiration

Stress is invisible until it isn't. Most of us don't notice we're tense until our shoulders are up at our ears.
Your skin notices first. When stress hits, your sweat glands react within a second or two, before you feel anything.
Waiting for surgery is one of the most stressful moments in a hospital, and patients usually just sit there with it.
We wanted to make that hidden signal visible and turn calming down into a game.

What it does

A small board on your hand reads your skin through two finger straps and turns it into a live stress level.
It learns your own calm level in about a minute, then tracks how far you drift from it.
Lanturn is a calming game for patients waiting before surgery. It runs in any browser.
It has three activities:
- Roots: trace a glowing vine by pointing your finger.
- Sight: a 5-4-3-2-1 grounding game where you find hidden things.
- Glow: take a deep breath, and the lantern waits until your body responds.
The world reacts to you. Calm brings out an aurora and brighter stars. When stress stays high, the lantern steps in and makes the activity easier.
The lantern talks in a calm voice and asks you to say kind words back, like "I am safe right now."
The patient never sees a number. A separate nurse view shows the stress timeline and which activity calms that patient most.

Hardware: a Seeed XIAO nRF52840 Sense with a Grove GSR sensor. The board's built-in motion sensor turns your finger into a pointer.
Firmware: reads the skin sensor 500 times a second and averages that down to 10 readings a second. That averaging also cancels the hum from power lines, in both 50 Hz and 60 Hz countries.
Stress engine (Python):
- Throws out bad readings (no contact, loose straps, sudden jumps) instead of guessing.
- Spots each quick skin response, and checks its shape to tell it apart from a strap shifting.
- Compares everything to your own baseline, because skin readings vary a lot between people and between days.
- Combines how often you react with how much your overall level has risen into one 0 to 100 score.
- Waits a few seconds before switching between calm and stressed, so the game doesn't flicker.
Finger pointing: we track which way your finger points, not where it moves, because tracking position drifts within seconds.
Server: streams everything live to the game and records every session, so we can replay it and tune the thresholds.
Game: HTML and JavaScript in the browser.
Voice: Cartesia Sonic 3.6 gives the lantern its voice, and Cartesia ink-whisper hears the player's kind words.

The official formula was wrong by 10x. Seeed's wiki assumes a 20 kΩ resistor, but the board uses 200 kΩ. We only found it by reading the schematic.
New straps need time to settle. Dry pads can double their reading in the first few minutes, which looks like panic. We made the baseline wait until the signal settles.
Moving your hand looks like stress. We filter out readings that jump too fast and responses that start while the hand is moving.
Breathing and talking raise the reading too. The game tells the sensor when it asks for a breath or a spoken word, so those don't count as stress.
Two sensors on one tiny board. We had to read the motion sensor without throwing off the skin sensor's timing.
No ground truth. You can't label your own stress in the middle of a hackathon, so we built a simulator and wrote 31 tests against it.

A working wearable that goes all the way from raw sensor to a game that reacts live.
Getting the physics right when the official docs were wrong.
A game that adapts to your body without ever showing a stress number.
One device that does two jobs: it reads your stress and it's your controller.
A nurse view that shows which activity helps each patient most.

The sensor measures arousal, not stress. Excitement, talking, deep breaths and heat all raise it too.
About 10 to 20% of people barely react on this kind of sensor, so the system has to notice that and say so.
The body is slow. Skin responses lag 1 to 3 seconds and the overall level can lag up to a minute, so slow, calm games work better than fast ones.
Read the schematic, not the wiki.