Fluid-Line Transducer for Patient Leakage Current Cancellation
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Solution Overview
Problem
Electric shock hazards from leakage current in patients connected to medical equipment can occur due to capacitive coupling of conductive fluid lines with ground potential, necessitating a solution to reduce leakage current.
Innovation Solution
A system that injects alternating current into conductive fluid lines to counteract leakage current by inducing a voltage drop, using contactless or contact transducers to equalize the patient's voltage with the medical device, employing sensors to measure and adjust the induced current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive coupling occurs between conductive fluid lines and ground potential surfaces, then electrical connection is established, but leakage current flows through the patient creating electric shock hazard
Solution Approach 1:
The system applies preliminary anti-action by detecting leakage current through the fluid line and injecting a counter-phase current to cancel it out before it reaches the patient. The controller monitors the leakage current and adjusts the injected current's magnitude and phase to preemptively neutralize the harmful effect, preventing electric shock hazard rather than merely responding after the fact.
Solution Approach 2:
The invention converts the harmful leakage current into a beneficial signal by using the same fluid line as both the carrier of potentially harmful current and the medium for injecting corrective current. The system measures the leakage current through the fluid line and uses this information to generate an equal and opposite current, transforming the harmful capacitive coupling effect into an opportunity for active cancellation and patient protection.
2Object-affected harmful factors
If alternating current is injected into the fluid line to counteract leakage current, then leakage current is reduced, but additional current flow is introduced into the system
Solution Approach 1:
The system applies partial action by injecting only the minimum necessary current to cancel the leakage current. The controller continuously monitors the actual leakage current magnitude and phase, adjusting the injected current to match exactly what is needed for cancellation rather than applying a fixed excessive current. This ensures energy efficiency while maintaining effective protection.
Solution Approach 2:
The invention implements feedback control by continuously measuring the leakage current through the fluid line and using this measurement to adjust the injected current's magnitude and phase. The controller forms a closed-loop system where the effect of the injected current is monitored and used to refine subsequent injection parameters, ensuring optimal cancellation with minimal energy consumption while adapting to changing conditions.
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
Effectively reduces leakage current to safe levels by matching the induced current with the leakage current, minimizing the risk of electric shock through the patient.
Implementation Method 1
The leakage current from a patient can be reduced by injecting alternating current into a blood line and thus inducting a voltage drop from the blood line entering the medical equipment under test (DUT)
Implementation Method 2
the fluid line may be capacitively coupled to a conductive surface next to or near the fluid line
Data Source
Figure 1A~1B
Figure 1C
Figure 2A~2B
AI summary
A sensor/transducer for use in reducing leakage current from a patient fluidly connected to a medical device by tubing filled with a conductive fluid (e.g., blood or dialysate (a "fluid line")) includes a magnetically conductive core with 1) a centrally located support for a coil of fluid line, and 2) coiled electrical conductors located at positions that are spaced from the centrally located support, on opposite sides of the centrally located support. The sensor/transducer can be used to measure leakage current carried by the conductive fluid in the fluid line, or it can be used to induce current in the fluid line in a manner that reduces the leakage current.