Microbot Control Using Pulsed Gradients in Commercial MRI
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Solution Overview
Problem
Commercial grade MRI scanners lack the necessary magnetic field gradients and compatibility with real-time imaging modalities to efficiently and safely control the motion of microbots within the body for localized drug delivery or minimally invasive surgery, posing safety hazards and inefficiencies in navigation and imaging.
Innovation Solution
The use of an MRI-safe lumen and adapter system within a commercial grade MRI scanner to introduce and control microbots, generating higher magnetic field gradients while ensuring safety through non-magnetic materials and mechanical guidance, and utilizing pre-scanned images with fiducial markers for real-time positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If commercial grade MRI scanner gradient coils are used to generate magnetic field gradients for microbot control, then the system can be operated with clinically approved hardware, but the maximum gradient strength is limited to below 100 mT/m which is insufficient for efficient microbot propulsion
Solution Approach 1:
The patent applies periodic pulsed gradient fields instead of continuous gradients. By delivering magnetic field gradients in repeated pulses at controlled intervals, the system accumulates propulsive effect on the microbot while allowing the gradient coils to rest between pulses, preventing overheating and staying within safe operational limits of clinically approved MRI hardware.
Solution Approach 2:
The patent dynamically adjusts gradient amplitude and pulse duration based on real-time microbot position and desired trajectory. The control system modulates the timing and strength of gradient pulses to optimize microbot propulsion efficiency while maintaining operation within the safety constraints of commercial MRI scanners.
2Productivity
If higher gradient amplitudes are applied to improve microbot propulsion efficiency, then faster and more effective navigation is achieved, but heat generation in gradient coils increases causing operational safety hazards
Solution Approach 1:
The system uses periodic pulsed gradients with controlled duty cycles to deliver propulsive force intermittently rather than continuously. This allows heat dissipation between pulses while maintaining effective average propulsion, resolving the contradiction between navigation speed and heat generation.
Solution Approach 2:
Through carefully designed pulse sequences and timing, the system maintains continuous useful propulsive action on the microbot while the gradient coils operate in a continuous-but-modulated manner that prevents overheating, ensuring both productivity and safety.
3Force
If custom-designed external hardware is used to generate high magnetic field gradients, then sufficient force for microbot control is achieved, but the complexity of the system increases and regulatory approval becomes more difficult
Solution Approach 1:
The patent makes the gradient coils perform dual functions: their primary function for MRI imaging and their secondary function for microbot propulsion. By utilizing existing multi-functional hardware, the system achieves high gradient capabilities without requiring separate custom-designed gradient generation equipment, reducing overall system complexity and regulatory burden.
Solution Approach 2:
The MRI scanner's existing gradient coil system serves itself by being repurposed for dual use in both imaging and microbot control. This self-service approach eliminates the need for additional dedicated hardware, simplifying the system architecture and regulatory approval process.
4Power
If the gradient coils operate at maximum capacity to provide sufficient magnetic force, then microbot control is effective, but the duty cycle is limited causing interruptions in control
Solution Approach 1:
The system employs periodic pulsed operation where gradient coils deliver maximum power in controlled pulses followed by rest periods for cooling. This allows effective microbot control during pulse intervals while managing thermal constraints, enabling sustained operation over extended durations through repeated pulse cycles.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient and safe control of microbots with gradients up to 500-1000 mT/m and real-time imaging, reducing heat generation and operational risks, allowing for sustained higher currents and extended duty cycles without overheating, and precise localization within the body.
Implementation Method 1
The background field magnetizes the ferrous components of the robot, and the gradient coils generate the magnetic gradient necessary to produce forces
Implementation Method 2
the gradient coils generate the magnetic gradient necessary to produce forces
Data Source
AI summary
The present disclosure provides methods of using a commercial grade magnetic resonance imaging (MRI) scanner to control and image motions of microbots in a subject. The method may further comprise a method of imaging to determine the location of the microbots in real time.