RayMing Physical Therapy Device PCBA

Key Components

1. Microcontroller: e.g., ARM Cortex-M4 or similar

   • Controls all device functions
   • Manages user interface
   • Handles data processing and storage

2. Power Management:

   • Battery management IC (for portable use)
   • AC-DC converter (for mains operation)
   • Multiple voltage regulators for different subsystems

3. Electrical Stimulation Module:

   • Digital-to-Analog Converter (DAC)
   • High-voltage amplifier circuit
   • Current-limiting safety circuit
   • Electrode connection interface

4. Ultrasound Therapy Module:

   • Ultrasound transducer driver circuit
   • Impedance matching network
   • Safety monitoring circuit

5. Biofeedback Module:

   • Analog-to-Digital Converter (ADC)
   • Instrumentation amplifiers
   • Filters for noise reduction

6. User Interface:

   • LCD or OLED display
   • Touch panel or membrane keypad
   • Status LEDs

7. Connectivity:

   • Bluetooth Low Energy (BLE) for wireless control and data transfer
   • USB for data transfer and potential charging

8. Storage:

   • EEPROM or Flash memory for settings and treatment protocols

 PCB Considerations

1. Layer Stack: 6-layer PCB recommended

   • Top layer: Components and signal routing
   • Inner layer 1: Ground plane
   • Inner layer 2: Power plane
   • Inner layer 3: Signal routing
   • Inner layer 4: Signal routing
   • Bottom layer: Components and signal routing

2. Component Placement:

   • Separate high-voltage sections from low-voltage control circuitry
   • Group analog and digital sections
   • Place sensitive components (e.g., ADCs) away from noise sources
   • Consider thermal management for power components

3. Signal Integrity:

   • Use controlled impedance for high-speed signals
   • Implement proper grounding and shielding techniques
   • Minimize crosstalk between different functional blocks

4. Power Distribution:

   • Implement star grounding technique
   • Use separate analog and digital grounds, joined at a single point
   • Consider split power planes for different voltage domains

5. Safety Considerations:

   • Implement isolation between mains-connected and patient-connected circuits
   • Use redundant safety mechanisms for critical functions
   • Design for fail-safe operation

6. Mechanical Considerations:

   • Plan for heat dissipation (especially for ultrasound module)
   • Include mounting points for enclosure and modules
   • Consider ergonomics and ease of assembly

Firmware Considerations

1. Implement different therapy modes (TENS, EMS, ultrasound, biofeedback)
2. Develop user-friendly interface for therapy selection and control
3. Implement safety checks and limits for all therapies
4. Data logging and analysis features
5. Bluetooth connectivity for remote control and data transfer
6. Calibration routines for accurate therapy delivery

Safety and Regulatory Considerations

1. Comply with medical device standards (e.g., IEC 60601-1, IEC 60601-2-10 for electrical stimulation)
2. Implement comprehensive electrical safety measures
3. Consider biocompatibility of materials for patient-contacting parts
4. Plan for EMC/EMI testing and certification
5. Implement software validation processes
6. Prepare risk management documentation
7. Plan for regulatory submissions (FDA, CE marking, etc.)