Implant Sensor-Actuator for Blood Flow Monitoring
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Solution Overview
Problem
Existing implantable sensors for monitoring blood flow often fail when overgrown with a bio-layer and are typically positioned near the lumen wall, causing occlusion and reducing their sensing ability, especially for long-term implants.
Innovation Solution
A sensor-actuator system that can deploy towards the center of the vessel, using an electroactive polymer sensor-actuator mounted on a stent-like support device, which can pivot into the flow to measure blood flow without occluding it, and has a bi-stable actuation mechanism to save power and prevent occlusion at the end of its life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the sensor is positioned near the lumen wall for implantation, then the insertion is simplified, but the sensor causes occlusion and reduces sensing ability
Solution Approach 1:
The sensor is designed to be movable between a retracted position (against the support device) and a deployed position (extending into the vessel lumen). This dynamic configuration allows the sensor to be inserted easily in the retracted state and then deployed to the optimal sensing position away from the wall, eliminating occlusion while maintaining sensing capability
Solution Approach 2:
The sensor-actuator device is divided into separate functional components: the support device (stent), the sensor element, and the actuator mechanism. This segmentation allows each component to be optimized independently - the support device provides structural support and easy insertion, while the sensor can be positioned optimally for measurement
2Duration of action of stationary object
If the sensor remains in place for long-term monitoring, then continuous unobtrusive sensing is achieved, but the sensor becomes overgrown with bio-layer and fails
Solution Approach 1:
The sensor can be dynamically repositioned or retrieved after initial deployment. This allows for periodic maintenance, cleaning, or replacement of the sensor element without requiring complete implant removal, thereby extending the operational lifespan while maintaining reliability
Solution Approach 2:
The sensor system incorporates self-diagnostic capabilities and can detect bio-layer accumulation. The actuator mechanism enables the sensor to self-adjust its position or trigger alerts when performance degradation is detected, allowing for proactive maintenance
3Measurement precision
If the sensor is deployed towards the center of the vessel for accurate measurement, then flow sensing ability is improved, but occlusion of the vessel occurs
Solution Approach 1:
The sensor-actuator mechanism enables dynamic positioning of the sensor element. The sensor can be extended into the vessel lumen to the optimal measurement position and then retracted when not in use, providing accurate flow measurements when deployed while minimizing occlusion when retracted
Solution Approach 2:
The sensor element is designed as a thin, flexible structure that can extend into the flow path without causing significant occlusion. The thin-film design allows the sensor to be positioned in the flow stream for accurate measurement while occupying minimal space in the vessel lumen
4Measurement precision
If the sensor-actuator is continuously actuated to maintain deployed position, then accurate flow monitoring is achieved, but energy consumption increases
Solution Approach 1:
Instead of continuous actuation, the sensor-actuator system uses periodic or on-demand actuation. The sensor can be deployed to the measurement position periodically for flow measurements and then retracted to a low-power state, significantly reducing energy consumption while maintaining monitoring capability
Solution Approach 2:
The actuation mechanism is replaced or supplemented with passive mechanical elements such as springs or elastic structures that can maintain the sensor in the deployed position without continuous energy input. The sensor naturally returns to a neutral position when actuation force is removed, eliminating the need for continuous power consumption
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 continuous, unobtrusive monitoring of blood flow away from the vessel wall, reducing occlusion and extending the lifespan of the implant by avoiding the need for frequent invasive procedures, while providing accurate flow measurements and early warning for potential issues.
Implementation Method 1
using an electroactive polymer sensor-actuator mounted on a stent-like support device
Data Source
AI summary
A monitoring system includes an implantable intra-vascular support device for positioning against a vessel wall and an implantable sensor-actuator mounted to the support device. The sensor-actuator is drivable between a non-deployed position in which it is against the support device and a deployed position in which it is displaced away from the support device. Sensor signals are generated when in the deployed position. This system is able to monitor flow away from the edge of a vessel by deploying the sensor-actuator towards the center of the vessel. When flow monitoring does not need to take place, it can be non-deployed so that it does not present an occlusion to the flow.