Hardware Design Engineer focused on wearable sensor integration and PCB design. This page documents the R&D process, design methodology, and troubleshooting logs for my current hardware projects.

• PCB Design: KiCad, Altium Designer (Schematic Capture, Layout, DFM)
• Embedded Systems: nRF5340, STM32WB, BLE Firmware integration
• Analog/Mixed Signal: ECG/EMG AFE designs, Audio/Optical systems
• Instrumentation: Oscilloscopes, Multimeters, Logic Analyzers

Redesign of previous wearable design for a more flexible form factor across muscle groups

• Objective: Design a wireless EMG sticker to enable any user to access physical activity data.
• Key Components: ADI MAX86178, nRF5340 MDBT53V-1M SOC, USB, rechargeable Li-Ion battery, nickel-free gold electrodes.

• Design Philosophy: Focus on a flexible "sticker" design to easily place on any muscle belly for improved performance tracking and muscle asymmetry detection on opposite limbs.

4-layer layout, 25 × 40 mm — top copper and silkscreen.	Flex electrode arm — nickel-free gold skin pad.
Fabricated board, top — MAX86178 AFE, nRF5340 module, USB-C charging.	Fabricated board, bottom — electrode pad and battery contacts.

• Debug Log / Lessons Learned:
  • Issue: None yet, in transit after fabrication.
  • Future Iteration: Improve flexibility by making the entire board a flex PCB with rigid fills as needed for BGA components.

• Current Phase: In transit from manufacturer, needs bring-up and verification. A companion iOS app is in development in parallel.

An initial prototype of a neural-feedback system for reading movement/muscle data and notifying the user of biomechanical events

• Objective: Design a wireless, multi-channel EMG to enable any user to access every-day movement patterns.
• Key Components: nRF5340 MDBT53-1M SOC, USB, rechargeable Li-Ion battery.

• Design Philosophy: Focus on design validation to improve the form factor in later iterations.
• Debug Log / Lessons Learned:
  • Issue: Button is not readable.
  • Root Cause: Self-assembly at hot-air bench was not sufficient for making electrical contact between the nRF5240 Module and the related button detection GPIO.
  • Resolution: Solder reflow with hot plate and hot air created the proper reflow profile at the module GPIO pin.
  • Future Iteration: Significantly reduce form factor to fit in mechanical housing and support adhesion to various body locations. WIrelessly connect to applications.

• Current Phase: Design verified to ensure functionality before intended final revision.

A compact, wall outlet compatible device for creating dynamic, color changing LED's that travel across the entire length of an LED Strip.

• Objective: Design an audio based system for reading audio signals, deriving the base frequencies, and changing the color of LEDs on the strip.
• Key Components: nRF5340 MDBT53-1M SOC, analog front end, buck converter, LDO.

• Design Philosophy: Focused on filtering out sound for ease of signal processing and FFT analysis.
• Debug Log / Lessons Learned:
  • Issue: Could detect target device when programming, but could not flash to the core.
  • Root Cause: Inadequate pad-to-pour clearance in the initial layout - short between GND and SWDCLK.
  • Resolution: Validated via continuity testing.
  • Future Iteration: Relocate GND via near SWDCLK on MDBT53-1M pads, reduce GND pour coverage near pads.

• Current Phase: Power/digital architecture validated. AFE and firmware validated on breadboard for full LED control. Redesign to relocate via and pour profile.

A compact, low-power wearable device for EMG signal acquisition.

• Objective: Design a small-scale wearable EMG sensor node with integrated BLE for remote monitoring.
• Key Components: STM32 MCU, Custom Analog Front End (AFE), LiPo Battery.

• Design Philosophy: Focused on miniaturization and high SNR for biosignals.
• CAD/Layout:
  
  
  
• Debug Log / Lessons Learned:
  • Issue: Encountered configuration issues when setting up STM32WB through STM32CubeIDE.
  • Root Cause: Inadequate reflow on STM32 during assembly.
  • Resolution: Validated via continuity testing.
  • Future Iteration: Design around reflow, select another chip.

• LinkedIn: www.linkedin.com/in/michael-miller-4b3918201
• Email: mmille7497@gmail.com