Electroactive Polymer Valve for CSF Drainage Control

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Solution Overview

Problem

Conventional cerebrospinal fluid (CSF) shunts for conditions like hydrocephalus are prone to mechanical failures, infections, and require frequent interventions due to their unreliability, leading to short lifespans and complications.

Innovation Solution

A body fluid drainage system with a valve device that applies incremental forces to a catheter to regulate drainage rate, incorporating sensors and a controller to monitor and adjust flow based on pressure and flow rate measurements, and features like anti-fouling coatings to reduce infection risk, along with a power-saving design for extended operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional CSF shunts are used, then drainage function is provided, but reliability is poor due to mechanical failures and infections

Engineering Contradiction:

Improvedevice reliabilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The shunt system is divided into separate functional modules: a catheter module for fluid transport, a valve module for pressure-regulated flow control, and a control module for adjusting valve characteristics. This segmentation allows each component to be optimized independently for reliability while maintaining overall system functionality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces traditional purely mechanical valve mechanisms with an electroactive polymer-based actuation system. The electroactive polymer can change its mechanical properties in response to electrical stimuli, enabling dynamic adjustment of valve characteristics without complex mechanical linkages, thereby improving reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If frequent interventions are performed to address failures, then device reliability is maintained, but loss of time and patient burden increase

Engineering Contradiction:

Improveshunt reliabilityVSAvoidtime between interventions

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system incorporates pressure sensors and flow sensors that continuously monitor CSF pressure and flow rate. This feedback is processed by a control algorithm that dynamically adjusts valve characteristics to maintain optimal drainage, enabling the system to adapt to changing physiological conditions and preventing failures that would require intervention.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The shunt system transitions from static valve characteristics to dynamic, adjustable characteristics. The valve resistance and opening pressure can be modified in real-time based on sensor feedback and control algorithms, allowing the system to maintain effectiveness throughout its operational life without requiring replacement or adjustment interventions.

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If simple mechanical valves are used, then device complexity is reduced, but measurement precision and drainage regulation capability are insufficient

Engineering Contradiction:

Improvepressure and flow measurement accuracyVSAvoidvalve control complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The control module serves multiple functions: it processes sensor data from pressure and flow sensors, executes control algorithms to determine optimal valve characteristics, and actuates the electroactive polymer valve mechanism. This multi-functionality integrates measurement, processing, and control capabilities into a single module, reducing overall system complexity while maintaining high measurement precision.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Reliability

If continuous monitoring and adjustment are implemented, then drainage regulation is optimized, but power consumption increases

Engineering Contradiction:

Improvedrainage regulation reliabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Instead of continuous actuation, the system uses periodic control where the electroactive polymer valve is adjusted at discrete time intervals based on accumulated sensor data and control algorithm decisions. This periodic action maintains effective drainage regulation while significantly reducing power consumption compared to continuous adjustment.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11247030B2Body fluid drainage system

Publication Date: 2022.02.15 UNIV OF WASHINGTON

AI summary

Drainage systems for excess body fluids and associated methods are disclosed herein. A body fluid drainage system in accordance with an embodiment of the present technology, for example, can include a catheter that has an exterior surface, a proximal portion, and a distal portion opposite the proximal portion. The body fluid drainage system can further include a valve device, a pressure sensor, and a controller operatively coupled to the valve device and the pressure sensor. The valve device can include an actuator positioned over the exterior surface of the catheter. The actuator is movable between an open position that allows body fluid flow through the catheter, a closed position that at least substantially obstructs the body fluid flow through the catheter, and intermediate positions that partially obstruct the body fluid flow through the catheter. The controller can change the position of the actuator in response to a predetermined condition of the pressure sensor.