HealthyPi Move is an open-source biometric monitor in a watch form factor. It supports continuous or intermittent monitoring of vital biometric signals like ECG, heart rate, HRV, PPG, SpO₂, blood-pressure trends, and respiration. HealthyPi Move is designed as a platform for innovation and customization, enabling users to integrate health tracking into their projects and personal wellness routines. The HealthyPi Move comes ready for everyday use and advanced research applications, in one device.

We designed HealthyPi Move according to the same principles as our larger HealthyPi products: open hardware, open-source software, clinical-grade precision, ease-of-use, and standalone operation without dependence on cloud services or paid subscriptions. The Move can be used for a wide range of applications, including personal health tracking, the development of healthcare-related devices, and even clinical research – with institutional review board (IRB) approval. If you have the resources to Shepherd your device through the FDA (or equivalent) certification and clearance process, you can use it for medical patient monitoring as well, and it already supports most of the capabilities you would need!

Own Your Device & Your Data

Data is the single most valued and traded item in the health industry lately, in part because of the need to train AI models for data-research studies. With the exception of a few open data-sharing platforms such as Physionet, most collected data is locked within proprietary systems where companies can sell it to the highest bidder. With HealthyPi Move, you own your health data. We don’t collect or sell your data, we don’t have a cloud service on which to store your data, and we don’t have a subscription model through which you and others can access your data. You can choose to share it with your health-care provider or with a research study on your own. Or, if you wish to train your own models or carry out your own research studies, you can use our open-source platform to gather data from participants, including yourself.

Truly owning any electronic device today is a challenge, as most devices are designed to be disposable, rather than repairable, with hidden screws, glued parts, and proprietary software. HealthyPi Move is designed to be maintainable and upgradable to protect your right to repair. Broke the display? Simply buy a replacement from our site (or a screen with the same specs from wherever) and replace it yourself. We designed the Move so you can open it up and fix it, which means it’s held together by screws and snaps rather than by glue like most devices. It’s also designed with modularity in mind, so the main board, sensor board, and battery are all easy to replace. Finally, HealthyPi Move is user programmable, so you can write your own algorithms and applications for it.

Sensors & Biometric Signals

The HealthyPi Move is packed with sensors to monitor a wide range of biometric signals. Here are some of the key sensors onboard:

Electrocardiogram (ECG)

ECG uses the electrical activity of the heart to indicate heart health. HealthyPi Move contains a single-lead ECG with one set of electrodes on the back of the device, which touches the skin of one wrist, and another electrode on the top side of the the device which you can touch with the finger of your other hand, thus forming a Lead-II type ECG configuration.

HealthyPi Move ECG Side electrode

The ECG data is processed by the onboard SoC and can be visualized in realtime on the display or sent to a smartphone or computer via Bluetooth (BLE). Heart-rate and HRV is also calculated from the ECG data in realtime. Respiration rate is also indirectly derived from the ECG using the EDR method.

Parameters derived from the ECG data include:

• Heart-rate
• Heart-rate variability (HRV)
• Respiration rate
• Other parameters—such as QT interval, QRS duration, etc.—that can be derived using your own algorithms

Photoplethysomogram (PPG)

HealthyPi Move comes with two PPG sensors in different locations, which is a first for a wearable device in this form factor. The wrist-based PPG is located under the device and is used for everyday heart rate and SpO₂ monitoring. The finger-based PPG is optional and plugs into the device’s USB Type-C port. It can be used for more accurate SpO₂ monitoring, which is particularly useful under low-perfusion conditions and for blood-pressure trend monitoring. Below is a picture of the HealthyPi Move wrist and finger sensors. The finger sensor shown here is a prototype worn with a band, but the final version will be integrated into a small, flexible finger ring connected to the main board with a flexible cable.

HealthyPi Move work with either the wrist sensor or the finger sensor, and can even run both simultaneously. This dual location PPG configuration opens up a new range of interesting applications, starting from everyday fitness tracking to blood pressure trending and pulse transit time (PTT) measurement, all using the same device. HealthyPi Move has two MAX32664 sensor hubs, one for the wrist sensor and one for the finger sensor. They come with medical-grade PPG algorithm libraries that can be used to calculate HR, SpO₂, and BPT values in addition to outputting raw data. The wrist sensor has four LEDs—two green, one red, and one infrared—and two photodiodes for reliable PPG data acquisition. The finger sensor has a MAX30101 sensor module with red and infrared LEDs and a photodiode.

Blood-pressure trending (BPT) is calculated in realtime using PPG data acquired from the finger sensor. A tiny sensor board integrated into the finger ring features a MAX30101 integrated optical sensor module, and the HealthyPi Move sensor board has an onboard MAX32664D biometric sensor hub, which provides a PPG algorithm library that can be used to calculate SpO₂ and BPT values. Several studies have shown that BPT values calculated from PPG data are comparable to values obtained using traditional cuff-based blood pressure monitors.

Parameters derived from PPG data include:

• Blood-oxygen levels (SpO₂)
• Blood-pressure trends (BPT) - finger sensor required
• Heart-rate
• Heart-rate variability (HRV)
• Other parameters—such as pulse transit time (PTT), sleep patterns, etc.—that can be derived using your own algorithms

Galvanic Skin Response (EDA/GSR)

EDA or GSR provide a measure of the electrical conductance of the skin, which varies with its moisture level. This is a good indicator of changes in mental state and can be used to monitor stress levels and emotional response. HealthyPi Move has two electrodes in the back that touch the skin of the wrist and measure the conductance of the skin, which correlates to EDA/GSR activity. GSR/EDA data can be recorded or visualized on the display.

Parameters derived from the EDA/GSR data include:

• Stress level (yet to be developed)
• Emotional response to stimuli (yet to be developed)
• Other parameters—such as skin conductance, body composition, etc.—that can be derived using your own algorithms

In addition to the above, HealthyPi Move has the following additional sensors onboard:

• A body temperature sensor (with a sensing pad on the back of the device)
• An inertial measurement unit (IMU) with 6-axis accelerometer and gyroscope to monitor your activity level. The IMU can be used to monitor physical activity, sleep patterns, and other parameters that requires motion sensing.

Onboard Computing & Interfaces

HealthyPi Move is powered by the Nordic nRF5340 dual-core SoC, which has a Cortex-M33 application processor and a Cortex-M33 network processor. The application processor runs the main application, and the network processor runs the BLE stack. The nRF5340 has 1 MB of on-chip flash and 512 KB of RAM, which is more than enough to run the HealthyPi Move application and user applications, with plenty of processing power to spare. The onboard 128 MB of flash is connected through a high speed QSPI interface and can be used to store up to 10 days of processed data, assuming a four-second sampling duration. The device can also be used to store raw data for shorter durations, making it perfect for stand-alone data collection without a smartphone or a computer.

Software Updates & Programming

Since the Zephyr software stack and the nRF Connect SDK both support the MCUBoot bootloader, HealthyPi Move can be updated with new software over the air (OTA) using the BLE interface from the HealthyPi mobile app or through the USB interface from a computer.

If you wish to program the nrf5340 directly with an nRF DK or any other J-Link programmer, you can do so by connecting the SWD pins to our programming adapter board which plugs into the USB Type-C port. The programming adapter board also has a UART interface that can be used to debug the application. The USB Type-C port is internally multiplexed to allow for SWD and UART access, charging, and data transfer. The multiplexing circuit on HealthyPi Move relies on the USB Sideband pins and Debug Accessory Mode (DAM) to achieve this functionality without hindering the normal operation of the USB Type-C port at full speed or fast charging with support for USB Power Delivery (PD).

Features & Specifications

• Microcontroller: Nordic nRF5340 dual-core ARM M33
• Sensors
  • MAX30001 ECG and bio-impedance front-end
  • MAX30101 Optical PPG Sensor
  • MAX32664 Sensor Hub
  • MAXM86146 wrist PPG sensor front-end with motion compensation
  • LSM6DSO 6-DoF IMU
  • MAX30205 Body Temperature Sensor
• Memory: 128 MB NOR QSPI flash memory for data storage
• Display: 1.28 inch TFT display with capacitive touchscreen
• Interfaces
  • Bluetooth Low Energy (BLE) 5.2
  • USB Type-C for data transfer, charging, JTAG and UART access (via USB Type-C Debug Accessory Mode)
  • 2x side push buttons for user input
• Power management: Nordic nPM1300 Single chip PMIC
  • Integrated 800 mA battery charger with USB Type-C Power Delivery support
  • 2x Integrated programmable buck converters for efficient power management
  • Integrated fuel gauge for battery monitoring
  • Integrated load switches for selective power management
  • 200 mAh Li-Po battery
  • USB Type-C charging port
• On-board realtime clock with super-capacitor backup
• Parameters Monitored
  • ECG
  • Heart-rate (from ECG or PPG Wrist or Finger sensor)
  • Heart-rate variability (HRV) (from ECG or PPG Wrist or Finger sensor)
  • PPG (from wrist or/and finger PPG sensor)
  • SpO₂ (from wrist or finger PPG sensor)
  • Blood Pressure (from finger PPG sensor only)
  • EDA/GSR
  • Respiration Rate (ECG derived)
  • Temperature
  • Activity levels and step count
  • Energy expenditure (calories burned)
• Software
  • Firmware based on Zephyr RTOS and nRF Connect SDK
  • Companion apps written in Flutter for Android, iOS, macOS, Windows and Linux
• Dimensions: 43 mm diameter, 16 mm thickness, compatible with 22 mm watch straps

Enclosure Design

The HealthyPi Move enclosure is designed to be simple, slim, accessible, and as light as possible while still being robust enough to hold the necessary sensors and electronics. The current version (shown in various pictures above) is an SLA 3D-printed version that we’ve been using for prototyping and testing. The final version of the enclosure will be injection molded and will be made of a biocompatible ABS-type material. The enclosure is designed so that the entire PCB and battery assembly can be inserted in one go from the back and secured with screws. The enclosure will include a strap-attachment mechanism that will accommodate any standard, 22 mm watch strap. Our enclosure has gone through numerous iterations (and is still undergoing changes) to ensure that it is comfortable to wear and easy to use. Several of those iterations are shown below:

We eventually plan to manufacture a premium, metal version of the enclosure that will be even more durable and stylish. This alloy enclosure will be made of a biocompatible material and will be sold as an accessory when it is available.

The finger ring sensor will be molded into a silicone-based material that will be flexible and comfortable to wear. It will connect to the main board using a flexible, detachable cable. Both enclosure designs are being developed in-house on Autodesk Fusion 360 and the source is available on our GitHub repo. Manufacturing of the enclosures will be carried out by trusted partners.

Comparisons

Support & Documentation

HealthyPi Move’s hardware and software are fully open-source, and we will provide extensive documentation to help you get started with your own projects. Our design files and software are available in our GitHub repositories:

• HealthyPi Move Hardware
• HealthyPi Move Software
• ProtoCentral OpenView 2 Mobile & Desktop Apps

Manufacturing Plan

We manufacture our own devices in-house, which allows us to maintain a high level of quality control and ensure that each device meets standards, with some parts such as enclosures produced by trusted partners. We have a well-established supply chain for key components, and we have already produced five prototype revisions and small testing batches.

Fulfillment & Logistics

Due to the high cost of shipping, and given the high volume of orders expected, the amazing people at Crowd Supply and Mouser Electronics will be handling fulfillment. All orders will ship from Mouser’s warehouse in the United States. Please see Ordering, Paying, and Shipping in Crowd Supply’s guide to learn more about their fulfillment service. Backers are responsible for paying import duties and taxes, if applicable.

Risks & Challenges

Our in-house production capability significantly reduces the risks associated with quality control and testing. In case we exceed our capacity, we have established relationships with reliable fabrication, assembly, and enclosure partners. HealthyPi Move went through several hardware iterations and multiple rounds of testing with different components before landing on this final design. Several of those iterations are shown below:

Although all hardware projects are exposed to risks associated with component shortages, shipping delays, and equipment breakdowns, we have gained valuable knowledge from previous projects. We are familiar with the factors that can cause delays and take preemptive action to avoid them. If such issues arise, we will do our best to resolve them promptly and keep you updated regarding any changes to our estimated schedule.

Important Warning

Although HealthyPi Move has many of the features of a medical-grade patient monitoring system, it does NOT have any certifications for medical use and is considered a consumer device for CE and UKCA marking purposes. It is NOT officially approved for medical or diagnostic use. It is your responsibility to ensure your safety when using the device. Furthermore, you should never power the device from a non-isolated power source or connect it to any other medical devices that are not isolated from the mains power supply. If you are planning to use the device for medical purposes, FDA or IRB approval is required. Please consult with your local regulatory authorities for more information.