Fluid Injector Pressure Calibration Using a Compressible Reference Load
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Solution Overview
Problem
Existing fluid delivery systems for medical procedures face challenges in accurately characterizing pressure and calibrating fluid injectors due to impedance and capacitance issues, leading to discrepancies in fluid delivery and inefficiencies, which existing calibration methods fail to address comprehensively.
Innovation Solution
A fluidless calibration system that includes a housing connected to the fluid injector, a drive member engagement portion, a compressible member, and a sensor to measure force or displacement, allowing for real-time calibration and tracking of pressure output, enabling early detection of faults and adjustments without the need for trained technicians.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing calibration methods are used, then fluid delivery can be performed, but pressure characterization is inaccurate due to impedance and capacitance issues
Solution Approach 1:
The patent extracts the calibration process from the actual fluid delivery system by using a fluidless calibration mode. The piston is calibrated against a reference pressure sensor without fluid impedance or capacitance interference, separating the calibration function from the delivery function to eliminate measurement errors caused by fluid dynamics.
Solution Approach 2:
A reference pressure sensor is introduced as an intermediary measurement device during calibration. This sensor directly measures the pressure generated by the piston without being affected by fluid impedance or capacitance, providing an accurate reference measurement that mediates between the piston output and the desired pressure characterization.
2Productivity
If fluid delivery is performed with system impedance and capacitance, then fluid can be delivered to the patient, but actual flow rate deviates from desired flow rate
Solution Approach 1:
The system performs calibration before actual fluid delivery to establish accurate pressure-flow relationships. By calibrating the piston in advance without fluid present, the system determines precise pressure characteristics that can then be used to compensate for impedance and capacitance effects during subsequent delivery operations.
Solution Approach 2:
The system uses feedback from the reference pressure sensor during calibration to accurately characterize pressure output at different piston positions and speeds. This feedback information is stored and applied during delivery to compensate for system impedance and capacitance, allowing the system to adjust and maintain accurate flow rates despite these inherent challenges.
3Reliability
If calibration is performed with fluid present, then actual fluid delivery conditions are simulated, but measurement accuracy is reduced due to impedance and capacitance
Solution Approach 1:
The system dynamically adapts between calibration mode and delivery mode. During calibration, fluid is excluded to enable precise measurement. During delivery, the stored calibration data is used with dynamic compensation algorithms that account for impedance and capacitance effects, allowing the system to maintain measurement precision across different operational states.
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
The system provides accurate and efficient calibration of fluid injector pressure output, reducing waste and ensuring precise fluid delivery by tracking changes over time and alerting to potential issues, thus improving the reliability and efficiency of medical fluid delivery systems.
Implementation Method 1
The compressible member is compressed with movement of the drive member of the fluid injector between a first, uncompressed position and a second, at least partially compressed position
Implementation Method 2
The sensor is configured for measuring a force imparted by the drive member when the compressible member is in the second, at least partially compressed position
Data Source
AI summary
A calibration system for calibrating a pressure output of a fluid injector having a housing configured for connecting to the fluid injector; a drive member engagement portion configured for contacting a drive member of the fluid injector; a compressible member, which may have a known modulus of compression, connected at its proximal end to the drive member engagement portion, wherein the compressible member is compressed with movement of the drive member of the fluid injector between a first, uncompressed position and a second, at least partially compressed position of the fluid injector in a distal direction; and a sensor connected to the compressible member is described. The sensor is configured for measuring at least one of a force imparted by the drive member and a displacement of the drive member when the compressible member is in the second, at least partially compressed position. The system may generate a calibration curve for the drive member of the fluid injector and allow the generation of a fault condition. Methods for calibrating a fluid injector are also described.