Tonometer Probe Magnetization Calibration Using Induced Voltage
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Solution Overview
Problem
Existing rebound tonometry methods face inaccuracies and potential eye damage due to the use of unsuitable ferromagnetic probes with varying magnetization saturation values, particularly in home-use devices where user error is possible.
Innovation Solution
A method for calibrating and identifying a tonometer probe by generating magnetic impulses and measuring induced voltage to ensure the probe reaches near or full saturation, comparing the result to a reference value, and rejecting probes that deviate by more than 0.1 millivolt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ferromagnetic probe is used in rebound tonometry, then the probe can be set into motion by a solenoid and impact the eye for IOP measurement, but the magnetization value may vary leading to incorrect IOP results and potential eye damage
Solution Approach 1:
The patent applies preliminary action by performing probe saturation and identification before actual IOP measurements. The system pre-saturates the ferromagnetic probe using repeated magnetic impulses and verifies its magnetization state by measuring induced voltage against reference values. This preliminary calibration ensures the probe is in the correct magnetic state before patient use, preventing measurement errors and potential eye damage from unsuitable probes
Solution Approach 2:
The system implements feedback by measuring the induced voltage in the coil when the probe impacts and comparing it to expected reference values. This feedback mechanism allows the system to verify whether the probe has the correct magnetization saturation and material properties. If the measured voltage deviates from the reference, the system can identify and reject unsuitable probes, ensuring only properly magnetized probes are used for measurements
2Adaptability or versatility
If multiple ferromagnetic materials are used for probes, then probe availability increases, but different magnetization saturation value curves lead to incorrect IOP results
Solution Approach 1:
The patent applies parameter changes by measuring and comparing the induced voltage parameter for each probe material type. Different ferromagnetic materials have different magnetization saturation curves, which manifest as different induced voltage values during probe impact. The system uses these voltage parameters to identify the specific material type and applies the corresponding reference value for accurate IOP measurement, allowing versatility with multiple materials while maintaining precision
3Device complexity
If probe magnetization is not fully saturated, then the device structure remains simple, but driving mechanics change from measurement to measurement leading to incorrect IOP
Solution Approach 1:
The patent applies periodic action by using repeated magnetic impulses to saturate the probe before measurement. The system delivers multiple cycles of magnetic field pulses to the ferromagnetic probe, progressively building up its magnetization to full saturation. This periodic magnetization process ensures consistent driving mechanics across all measurements without requiring complex permanent magnetization mechanisms, maintaining device simplicity while achieving measurement reliability
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
Ensures accurate intraocular pressure measurements and prevents eye damage by verifying the correct probe material and magnetization before use, enhancing safety and reliability in tonometry devices.
Implementation Method 1
generating an initial magnetic impulse upon the probe via a first electromagnetic coil using known impulse parameters
Implementation Method 2
generating a magnetic impulse via an electromagnetic coil to reverse probe velocity
Implementation Method 3
measuring a resultant-induced voltage upon a measuring electromagnetic coil from the motion of the probe upon an Nth cycle
Implementation Method 4
the probe becomes magnetized when subjected to a magnetic field and behaves like a magnet. The degree of magnetization is determined by the probe material's magnetic parameters including magnetic saturation
Implementation Method 5
A ferromagnetic material, the probe becomes magnetized when subjected to a magnetic field and behaves like a magnet
Data Source
AI summary
A method for calibrating and identifying a tonometer probe includes the steps of: a) generating an initial magnetic impulse upon a probe of ferromagnetic material via a first electromagnetic coil using known impulse parameters, b) generating a magnetic impulse via an electromagnetic coil to reverse probe velocity, c) repeating steps a)-b) for N cycles, d) measuring a resultant-induced voltage upon a measuring electromagnetic coil from probe motion, e) comparing the resultant-induced voltage upon the measuring electromagnetic coil to a reference value, and f) rejecting the probe if the induced voltage measured by the measuring electromagnetic coil is different than the reference value after N cycles.