WULPUS:

Wearable Ultra Low-Power Ultrasound

Introduction

This repository contains the work in progress on the WULPUS ultrasound probe.

WULPUS is a truly wearable ultra-low-power open research ultrasound platform.

The probe has the following features:

• 8 channels (time-multiplexed)
• 8 Msps Analog-to-Digital converter (12 bit resolution)
• 30.8 dB Programable-Gain Amplifier + 10 dB Operational Amplifier
• Bluetooth Low Energy (BLE) wireless link (320 kbps throughput)
• Up to 50 acquisitions per-second (APS) (400 samples per acquisition, raw data streaming mode)
• Compactness (46 x25 mm footprint)
• Ultra-Low Power consumption of 22 mW (raw data streaming mode, 50 APS)

WULPUS system diagram

WULPUS probe comprises two printed circuit boards (PCBs):

• Acquisition PCB: featuring an ultrasound MCU (MSP430FR5043) and BLE MCU (nRF52832)
• High-Voltage PCB: featuring a High-voltage multiplexer (HV MUX), a transmit/receive switch, and a MOSFET driver.

WULPUS System Diagram

Structure of the repository

This repository has the following folders:

• fw, containing the firmware source code, namely:

  • source code for the nRF52832 MCU of the WULPUS probe, located at fw/nrf52/ble_peripheral/US_probe_nRF52_firmware
  • source code for the nRF52840 USB dongle, located at fw/nrf52/peripheral/US_probe_dongle_firmware
  • source code for the MSP430 ultrasound MCU (will be added in the next release under the fw/msp430 folder)

• sw, containing the Python code for the WULPUS Graphical User Interface

• hw, containing the Altium designer source files and pdf schematics for

  • WULPUS Acquisition PCB (located at hw/wulpus_acquisition_pcb)
  • WULPUS High-Voltage PCB (located at hw/wulpus_hv_pcb)

• docs, containing the project documentation (e.g., images of the device, user guide, ...)

How to reproduce?

To build your own instance of WULPUS, the following steps should be completed:

1. PCBs manufacturing and assembly
   You can find the design files (Altium source files, schematics, bills of materials) under the hw folder.
2. Flashing MSP430 firmware
   You can find the instructions on seting-up the toolchain, compiling the firmware and flashing the MSP430 MCU in the fw/msp430 folder.
3. Flashing nRF52 MCU and USB dongle firmware
   You can find the instructions on setting-up the toolchain, compiling the firmware, flashing the nRF52 MCU and USB dongle in the fw/nrf52 folder.
4. Python dependencies installation on the host PC
   Follow the instructions in the sw folder to install the dependencies.

Usage

• Power up the probe, either from the micro-USB connector or from the battery connector
• Connect the USB dongle to the host PC
• Activate the Python environent, launch the Jupyter notebook located in sw folder, and follow the instructions in the notebook

Citation

If you would like to reference the project, please cite the following paper:

@inproceedings{frey2022wulpus,
  title={WULPUS: a Wearable Ultra Low-Power Ultrasound probe for multi-day monitoring of carotid artery and muscle activity},
  author={Frey, Sebastian and Vostrikov, Sergei and Benini, Luca and Cossettini, Andrea},
  booktitle={2022 IEEE International Ultrasonics Symposium (IUS)},
  pages={1--4},
  year={2022},
  organization={IEEE}
}

Authors

The WULPUS system was developed at the Integrated Systems Laboratory (IIS) at ETH Zurich by:

• Sergei Vostrikov (Firmware, Software, Open-Sourcing)
• Sebastian Frey (Firmware, PCB design)
• Luca Benini (Supervision, Conceptualization)
• Andrea Cossettini (Supervision, Project administration)

References

[1] - Frey, Sebastian, Sergei Vostrikov, Luca Benini, and Andrea Cossettini. "WULPUS: a Wearable Ultra Low-Power Ultrasound probe for multi-day monitoring of carotid artery and muscle activity." In 2022 IEEE International Ultrasonics Symposium (IUS), pp. 1-4. IEEE, 2022.

License

The following files are released under Apache License 2.0 (Apache-2.0) (see sw/LICENSE):

• sw/

The following files are released under Solderpad v0.51 (SHL-0.51) (see hw/LICENSE):

• hw/

The following files are released under Creative Commons Attribution 4.0 International License (CC-BY-4.0) (see docs/images/LICENSE):

• docs/images/

The fw/msp430/ and fw/nrf52/ directories contain third-party sources that come with their own licenses. See the respective folders and source files for the licenses used.