Phaco Probe Flow Sensing for Stable Intraocular Pressure
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Solution Overview
Problem
Existing phacoemulsification systems face challenges in accurately measuring aspiration and irrigation flow rates, which affect intra-ocular pressure, leading to potential eye damage due to fluctuations and pressure differences.
Innovation Solution
Incorporation of pressure sensors at proximal and distal locations within the aspiration and irrigation channels of the phacoemulsification probe, coupled with a processor to calculate flow rates by analyzing pressure variations and channel dimensions, enabling precise control of fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate aspiration and irrigation pumps are used to control fluid flow, then the ability to independently control aspiration and irrigation rates is improved, but the accuracy of flow rate measurement deteriorates due to oscillations and pressure differences
Solution Approach 1:
The patent introduces flow meters as intermediary devices in the fluid pathways between the pumps and the eye. These flow meters directly measure the actual flow rates of aspiration and irrigation fluids, providing accurate measurement data that is fed back to the processor. This intermediary measurement mechanism resolves the contradiction by decoupling the control function (pumps) from the measurement function (flow meters), allowing independent control while achieving precise measurement.
Solution Approach 2:
The system implements feedback control by continuously monitoring flow rates with flow meters and using this information to adjust pump operations. The processor receives real-time flow rate data from the flow meters and uses this feedback to maintain accurate flow control, compensating for oscillations and pressure differences that would otherwise degrade measurement accuracy.
2Ease of operation
If pump rates are set nominally by the processor, then the ease of operation is improved, but the reliability of actual flow rate control deteriorates due to oscillations and tubing effects
Solution Approach 1:
The system uses flow meters to provide real-time feedback on actual flow rates, which are compared against nominal rates set by the processor. This feedback loop enables the processor to make real-time adjustments to pump operations, ensuring that actual flow rates match the intended nominal rates despite oscillations and tubing effects, thereby maintaining reliability while preserving ease of operation.
Solution Approach 2:
The patent replaces direct mechanical control of flow rates with an electronic control system that uses flow meter data to adjust pump operations. This substitution of mechanical feedback with electronic sensing and control allows for more precise and reliable flow rate management, as the electronic system can rapidly respond to deviations from nominal rates.
3Measurement precision
If pressure sensors are placed in the channels, then the measurement precision of flow rate is improved, but the device complexity increases due to additional sensors and processing requirements
Solution Approach 1:
The patent introduces flow meters as intermediary measurement devices that directly measure flow rates without requiring complex pressure sensor arrays. These flow meters simplify the measurement system by providing direct flow rate data, avoiding the need for multiple pressure sensors and complex calculations, thus improving measurement precision while limiting the increase in device complexity.
4Ease of operation
If the tubing lines are made long to connect pumps and channels, then the ease of operation and setup is improved, but the measurement precision of flow rate deteriorates due to flow rate variations along the tubing
Solution Approach 1:
The patent places flow meters at strategic locations within the tubing system to directly measure flow rates at the point of interest (near the eye). This intermediary measurement approach allows for long, flexible tubing connections between pumps and channels while maintaining measurement precision, as the flow meter captures the actual flow rate at the critical location regardless of upstream variations.
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
Accurately measures and controls aspiration and irrigation flow rates, maintaining stable intra-ocular pressure and preventing eye damage during cataract surgery.
Implementation Method 1
a first pressure sensor coupled with the channel at a first position... a second pressure sensor coupled with the channel at a second position
Data Source
AI summary
Apparatus for determining a fluid flow rate in a channel of a phacoemulsification probe, including a first pressure sensor, coupled with fluid in the channel at a first position. A second pressure sensor couples with the fluid in the channel at a second position, at a preset distance from the first position, and the fluid flows from the first to the second position. A processor acquires from the first pressure sensor first indications of a pressure profile of a portion of the fluid passing the first pressure sensor, and acquires from the second pressure sensor second indications of a pressure profile of the fluid passing the second pressure sensor. The processor correlates the first and second indications to determine a time for the fluid portion to travel from the first to the second position, and calculates the fluid flow rate in response to the time and the preset distance.