Non-Magnetic Piezoelectric Pumps for MRI Safety

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Solution Overview

Problem

Conventional medical devices, such as blood pressure and gas monitors, containing ferrous materials are unsafe for use in MRI environments due to magnetic attraction risks and interference with magnetic fields, which can cause safety hazards and image distortion.

Innovation Solution

Development of non-magnetic pumps, including piezoelectric and ultrasonic motor-driven pumps, designed to operate safely within MRI environments by using materials that avoid magnetic attraction and minimizing RF interference, such as piezoelectric discs and rotary ultrasonic motors with specific drive circuits to manage fluid flow and pressure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional motors and pumps with ferrous materials are used in blood pressure and gas analyzer monitors, then the devices can perform their monitoring functions, but they create safety hazards in MRI environments due to magnetic attraction and projectile risks

Engineering Contradiction:

Improvesafety in MRI environmentVSAvoidmagnetic attraction and projectile risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes ferrous materials and magnetic components from the pump design, extracting the harmful elements that cause magnetic attraction and projectile risks in MRI environments. The pump uses non-magnetic materials throughout, eliminating the safety hazards while maintaining pumping functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces traditional electromagnetic motors with a piezoelectric actuation system. The piezoelectric member converts electrical signals directly into mechanical motion to drive the pump, eliminating the need for ferrous motor components and their associated magnetic field problems in MRI environments.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Strength

If ferrous materials are used in pump construction, then structural strength and motor performance are achieved, but magnetic fields are produced that can become projectiles in MRI environments

Engineering Contradiction:

Improvestructural strengthVSAvoidmagnetic field projection

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent employs composite material construction, particularly using piezoelectric ceramics combined with non-magnetic metals or polymers. This composite approach provides the necessary structural strength while maintaining non-magnetic properties that prevent projectile behavior in MRI environments.

Inventive Principle:

Principle #40Composite materials

3Power

If common motors are used to drive the pump, then adequate power and speed are achieved, but radiofrequency interference is generated that disrupts MRI imaging

Engineering Contradiction:

Improvepump powerVSAvoidradiofrequency interference

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The patent substitutes electromagnetic motors with a piezoelectric actuation system that generates mechanical motion through crystal lattice expansion and contraction. This substitution eliminates the radiofrequency interference and electromagnetic emissions that disrupt MRI imaging, while the piezoelectric materials provide sufficient power for pump operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If piezoelectric members are used to eliminate magnetic materials, then safety in MRI environment is improved, but dead space in pump chamber increases reducing efficiency

Engineering Contradiction:

Improvesafety in MRI environmentVSAvoidpump efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent employs a dynamic pump chamber design where the piezoelectric member's expansion and contraction continuously alter the chamber volume. This dynamic operation minimizes dead space by ensuring the chamber is fully utilized during each pump cycle, maintaining high efficiency while using non-magnetic piezoelectric materials for safety.

Inventive Principle:

Principle #15Dynamics

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

These pumps enable continuous patient monitoring in MRI environments without safety hazards or image distortion, ensuring reliable operation and accurate data acquisition by avoiding magnetic attraction and RF interference.

Implementation Method 1

a piezoelectric member (e.g., plate, disc) positioned inside the pump housing, a drive circuit configured to energize the piezoelectric member. The piezoelectric member, when energized, is configured to deflect into the pump chamber

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS11268506B2Fluid pumps for use in MRI environment

Publication Date: 2022.03.08 IRADIMED CORP

AI summary

Embodiments of fluid pumps configured for use in a magnetic resonance imaging environment are disclosed. The pumps may include piezoelectric driven pumping mechanisms or ultrasonic motor driven pumping mechanisms. The pumps may be configured to pump fluid such as air or liquid. The pumps may be incorporated in a multi-parameter patient monitoring system.