Aspiration Flow Signal Bubble Filter
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Solution Overview
Problem
The measurement of aspiration flow rate in ophthalmic microsurgical pump systems is challenging due to the presence of air bubbles, which disrupt fluid flow and hinder accurate flow rate measurement.
Innovation Solution
An aspiration flow measurement system that includes a flow channel and a control system to detect and filter out signal disruptions caused by air bubbles, using a median filter and threshold-based algorithms to generate a filtered signal indicative of the flow rate exclusive of bubble-induced errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If air bubbles are present in the aspiration flow, then the flow rate measurement becomes disrupted and inaccurate, but removing air bubbles completely may require additional filtering components that increase device complexity
Solution Approach 1:
The patent extracts and removes air bubbles from the aspiration flow path using a filter component integrated into the surgical cassette. This extraction principle directly addresses the measurement accuracy problem by eliminating the harmful air bubbles that cause signal disruptions, while the integration into the existing cassette structure minimizes the added complexity
Solution Approach 2:
The patent introduces an intermediary filtering mechanism that mediates between the aspiration flow containing air bubbles and the flow rate sensor. This intermediary filter allows the sensor to measure only the fluid flow without direct exposure to air bubbles, resolving the contradiction by protecting the measurement system while maintaining overall system simplicity
2Measurement precision
If a filter is added to remove air bubbles, then measurement accuracy improves, but the filter may create additional pressure drop or flow resistance
Solution Approach 1:
The patent employs a porous filter material that allows fluid to pass through while trapping air bubbles. The porous structure provides effective bubble removal with minimal flow resistance, balancing measurement accuracy improvement against pressure drop concerns by allowing efficient fluid passage while blocking harmful air bubbles
Data Source
AI summary
In an aspiration flow measurement system, a flow channel is provided for receiving an aspiration fluid flow therethrough. The flow measurement system further includes an aspiration flow measurement chamber and a flow sensor that is configured to generate a raw signal indicative of the rate of fluid flow through the flow channel. A control system is configured to monitor the signals indicating the flow through the flow measurement chamber, and to determine when a value of the raw signal is indicative of a disruption caused by the presence of an air bubble, wherein the control system generates a filtered signal of the flow rate that is exclusive of any signal values that are indicative of a disruption.