Open-LIFU Verification Tank

A Python-based system for automated acoustic field verification and characterization of focused ultrasound transducers using the Open-LIFU platform.

Overview

The Open-LIFU Verification Tank provides a comprehensive solution for measuring and characterizing focused ultrasound acoustic fields. It integrates multiple instruments and provides high-level automation for common verification tasks, including beam profiling, frequency response measurement, and focus optimization.

Key Features

• Multi-instrument coordination: Seamless integration of transducer control, data acquisition, and power management
• Automated measurements: Built-in scanning, peak finding, and field mapping capabilities
• Calibrated pressure measurements: Support for calibrated hydrophones with frequency-dependent sensitivity
• High-speed data acquisition: Integration with PicoScope oscilloscopes for precision timing
• Flexible control: Programmable power supply control with voltage settling detection

System Components

Hardware

• Open-LIFU Transducer System: Multi-element focused ultrasound transducer with beam steering
• PicoScope 5000A Series: High-speed USB oscilloscope for data acquisition
• AIM TTi QPX600DP: Dual-channel programmable power supply for drive voltage control
• Calibrated Hydrophone: Precision pressure sensor with tank positioning system

Software

• Python API: Object-oriented interfaces for each system component
• Automation Scripts: Ready-to-use measurement scripts for common tasks
• Documentation: Comprehensive API documentation and examples

Installation

Prerequisites

1. Hardware Setup

   • Connect PicoScope via USB and install drivers from Pico Technology
   • Connect QPX600DP power supply via USB and install AIM TTi drivers
   • Set up Open-LIFU system according to the manufacturer's instructions
   • Install a hydrophone in the tank positioning system
   • Connect Channel A of the Picoscope to the Hydrophone Output, and channel B to the trigger output of the Open-LIFU system (optional)

2. Python Environment

   # Python 3.8+ recommended
   pip install numpy scipy pandas matplotlib
   pip install pyserial
   pip install picosdk
   pip install openlifu

3. Clone Repository

   git clone https://github.com/OpenwaterHealth/OpenLIFU-verification-tank.git
   cd OpenLIFU-verification-tank
   pip install -e .

Quick Start

Basic Pressure Measurement

from openlifu_verification import VerificationTank, Hydrophone
from pathlib import Path

# Load hydrophone calibration
hydrophone = Hydrophone(Path("hydrophone_calibrations/your_calibration.txt"))

# Measure pressure at focus
with VerificationTank(frequency=400) as tank:
    # Configure system
    tank.configure_lifu(
        frequency_kHz=400,
        voltage=50,
        duration_msec=1.0,
        interval_msec=100
    )
    
    # Set focus position  
    tank.set_focus(x=0, y=0, z=30)  # mm coordinates
    
    # Capture data
    data = tank.run_capture()
    
    # Convert to calibrated pressure
    sensitivity = hydrophone.get_sensitivity_pa_per_v(400e3)
    pressure_pa = data['A'] * sensitivity
    
    peak_pressure = np.max(pressure_pa)
    print(f"Peak pressure: {peak_pressure:.0f} Pa")

Automated Field Mapping

# 2D beam profile measurement
with VerificationTank() as tank:
    tank.configure_lifu(frequency_kHz=1000, voltage=75, duration_msec=0.5, interval_msec=50)
    
    # Define scan grid
    x_positions = np.linspace(-10, 10, 21)  # ±10 mm
    y_positions = np.linspace(-10, 10, 21)
    z_focus = 25
    
    # Automated scanning
    pressure_map = np.zeros((len(x_positions), len(y_positions)))
    
    for i, x in enumerate(x_positions):
        for j, y in enumerate(y_positions):
            pressure_map[i, j] = tank.get_peak_voltage(x, y, z_focus)
    
    # Analyze results
    peak_location = np.unravel_index(np.argmax(pressure_map), pressure_map.shape)
    print(f"Peak at ({x_positions[peak_location[0]]:.1f}, {y_positions[peak_location[1]]:.1f}) mm")

Example Scripts

The scripts/ directory contains ready-to-use measurement scripts:

• single_pulse.py: Single-point pressure measurement
• scan_2d.py: 2D beam profile mapping
• scan_frequency.py: Frequency response characterization
• scan_voltage.py: Drive voltage linearity measurement
• find_peak.py: Automated focus optimization
• plot_*.py: Visualization utilities for measurement data

API Documentation

Comprehensive API documentation is available in the docs/ directory:

• API Overview: Complete system documentation and usage guide
• Hydrophone Class: Calibrated pressure measurement interface
• Picoscope Class: High-speed data acquisition interface
• QPX600DP Class: Programmable power supply interface
• VerificationTank Class: High-level system coordination

Configuration

Transducer Setup

Transducer configurations are stored as JSON files in the transducers/ directory:

{
  "name": "OpenLIFU 1x180 EVT1",
  "frequency_hz": 1000000,
  "element_count": 180,
  "geometry": "...",
  "focus_distance_mm": 30.0
}

Hydrophone Calibration

Place hydrophone calibration files in hydrophone_calibrations/ directory. Supports standard formats from:

• Onda Corporation
• Precision Acoustics
• Other manufacturers using similar text-based formats

Safety and Best Practices

Safety Guidelines

• Always use appropriate drive voltage limits for your transducer
• Implement proper interlock systems for high-power operation
• Monitor for cavitation and heating effects during extended operation
• Ensure proper grounding and electrical safety measures

Measurement Best Practices

• Allow adequate settling time between measurements
• Use appropriate sampling rates for your frequency range
• Calibrate the positioning system regularly
• Account for temperature effects on sound speed and sensitivity
• Implement error handling for robust automated measurements

System Maintenance

• Regularly verify instrument calibration
• Check mechanical positioning accuracy
• Monitor cable connections and signal integrity
• Keep software and drivers updated

Contributing

We welcome contributions to improve the OpenLIFU Verification Tank system:

1. Fork the repository and create a feature branch
2. Add tests for new functionality in the tests/ directory
3. Update documentation for API changes
4. Submit a pull request with a clear description of changes

Development Setup

git clone https://github.com/OpenwaterHealth/OpenLIFU-verification-tank.git
cd OpenLIFU-verification-tank
pip install -e .[dev]  # Install with development dependencies
pytest tests/          # Run test suite

Troubleshooting

Common Issues

Instrument Connection Problems

• Verify USB connections and driver installations
• Check that no other software is using the instruments
• Ensure proper user permissions for device access

Measurement Accuracy Issues

• Verify hydrophone calibration and positioning
• Check for proper acoustic coupling
• Ensure stable temperature conditions
• Validate trigger settings and signal levels

Performance Problems

• Optimize sampling parameters for your application
• Use appropriate resolution modes based on signal amplitude
• Consider measurement time vs. spatial resolution trade-offs
• Implement efficient scanning patterns

Getting Help

• Check the API documentation for detailed usage information
• Review example scripts in the scripts/ directory
• Run the test suite to verify system functionality
• Submit issues on GitHub with detailed error descriptions

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• OpenLIFU development team for the core transducer control platform
• Pico Technology for PicoScope SDK and support
• AIM TTi for power supply control protocols
• Contributors to the open-source Python scientific computing ecosystem

Citation

If you use this software in your research, please cite:

@software{openlifu_verification_tank,
  title = {OpenLIFU Verification Tank},
  author = {Openwater Health},
  url = {https://github.com/OpenwaterHealth/OpenLIFU-verification-tank},
  year = {2024}
}