PPG module
Optical pulse sensing for heart rate, HRV, and SpO2-related research signals.
- For pilots
- recovery, exertion, safety context
- Chip
- MAXM86161
Hardware
Three sensor positions. One configurable band.
OpenPulse combines two modules that touch the wrist for body signals with one module that faces outward for context like gas, heat, or humidity. The same band can become a research wearable, safety monitor, or wellness pilot device.
swap sensor module
upgrade without replacing the band
open signal path
Main PCB: Seeed XIAO nRF52840 Sense
environment sensor faces outward
body sensors touch the wrist
Architecture at a glance
One core board. Three places to measure.
The main PCB handles power, BLE, compute, and the sensor bus. The round modules define what the band measures: two collect wrist-contact body signals, while one looks outward at the surrounding environment.
2wrist-contact modules for body signals
1outward module for environment context
36x20mm class main PCB footprint target
Modularity is the product
The sensor module comes out. The use case changes.
For a layperson, this means a wearable that can be configured instead of replaced. For a technical partner, it means a repeatable hardware interface for new sensors, validation runs, and specialized signal stacks.
Specializeresearch, safety, wellness, open-source builds
Repairreplace a sensor module instead of the whole band
Upgradenew sensor generation, same core architecture
Sensor modules
Simple explanation first. Chip-level detail second.
Each round module is a small replaceable sensor board. First we explain what it measures and why a pilot might need it; then the chip-level detail is available for engineers.
EDA / Bioimpedance
Skin conductance and impedance signals for stress, arousal, and response studies.
- For pilots
- research, neuromarketing, GBU-Psyche
- Chip
- MAX30009
Skin temperature
High-resolution temperature tracking as context for recovery, environment, and safety.
- For pilots
- wellness, heat exposure, trend tracking
- Chip
- TMP117
IMU
Movement, posture, and activity context that helps interpret physiological signals.
- For pilots
- sports, safety, artifacts, activity context
- Stack
- accelerometer / motion primitives
Microphone
Acoustic context for controlled pilots where sound events matter to the measurement setup.
- For pilots
- environmental context, interaction studies
- Status
- configuration-dependent
Environment module
Sensing that faces away from the wrist for gas, humidity, temperature, or other workplace context.
- For pilots
- workplace safety, industrial environments
- Position
- faces away from the wrist
Full specs
Enough detail for engineers. Still skippable for everyone else.
OpenPulse should never bury the product in jargon. But serious pilot partners need to see that the architecture has real engineering decisions behind it.
Firmware and connectivity
- Seeed XIAO nRF52840 Sense as the current main compute/BLE platform.
- Zephyr RTOS target for structured firmware development.
- BLE for device communication, MQTT in the data path from day one.
Signal processing
- NeuroKit2 primitives for transparent biosignal processing where applicable.1
- Classical DSP first, narrow ML use only where it adds measurable value.
- Pipeline goal: acquisition -> primitives -> composite metrics -> use-case outputs.
Power, housing, and status
- Approx. 120 mAh battery class and 30+ hour target depending on configuration.
- IP54 target for pilot hardware.
- ECG is framed as a V2 housing/band-closure contact concept, not as a removable module claim.
Open software architecture
The hardware is modular. The signal path should be modular too.
01
Acquisition
Raw sensor channels from module-specific drivers.
02
Primitives
EDA, PPG, temperature, motion, and environment processing blocks.
03
Composite
Use-case-aware signal combinations, not one uniform algorithm for all.
04
YAML pipelines
Configurable recipes for pilots and repeatable studies.
05
Outputs
MQTT, dashboards, exports, app integrations, or local alerts.
Data sovereignty
No forced cloud as the center of the product.
OpenPulse is designed for local processing, open APIs, exportable data, and pilots where the partner can understand what is measured and how the signal is transformed.