Surgical Locator Circuit Sensor Signal Normalization
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Solution Overview
Problem
Conventional surgical positioning devices face challenges due to subtle variations in individual electronic components, leading to inconsistent signal responses and positioning errors during minimally invasive procedures like kidney stone removal.
Innovation Solution
A surgical locator circuit with a fixed element and signal conditioner normalizes sensor signals from an array of sensors, ensuring consistent positioning information by using a modified Wheatstone bridge configuration with magneto resistors and fixed resistors to account for variations in sensor responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electronic components are used in surgical positioning devices, then the device can be manufactured with standard components, but subtle variations in component characteristics lead to inconsistent signal responses and positioning errors
Solution Approach 1:
The patent applies parameter changes by modifying the Wheatstone bridge configuration to include fixed reference elements that establish a stable baseline. The bridge circuit parameters are adjusted so that the output signal depends on the differential change in resistance rather than absolute resistance values, thereby compensating for component variations and improving positioning accuracy.
Solution Approach 2:
The fixed reference resistor serves as an intermediary element that mediates between the variable magneto-resistive sensors and the measurement system. This reference element provides a stable comparison point that allows the system to distinguish between signal changes caused by magnetic field variations and those caused by component tolerances.
2Device complexity
If individual sensor variations are not compensated, then the circuit design remains simple, but positioning information becomes inconsistent and unreliable
Solution Approach 1:
The patent transforms the sensor array into a differential measurement system by changing the circuit parameters. The Wheatstone bridge converts absolute resistance measurements into differential voltage outputs, where the fixed reference elements establish a null point that eliminates the need for individual sensor calibration while ensuring consistent positioning information.
3Measurement precision
If magneto-resistive sensors are used to detect magnetic field variations, then distance and direction can be determined, but subtle variations in sensor response create inconsistent signals
Solution Approach 1:
The patent applies parameter changes by configuring the magneto-resistive sensors in a Wheatstone bridge arrangement where the output signal represents the differential change in resistance. This transformation allows the system to measure magnetic field-induced resistance changes while automatically compensating for manufacturing variations in the baseline resistance of individual sensors.
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
This approach provides precise and consistent positioning information, reducing the risk of incorrect needle insertion and improving the accuracy of surgical procedures by compensating for subtle variations in sensor responses, thereby enhancing the precision of surgical interventions.
Implementation Method 1
In the case of a magneto resistor sensor, a variable resistance is responsive to the distance and direction from the magneto resistor to an emitter defined by a magnetic coil emitting a magnetic field
Implementation Method 2
The combined magneto resistor and fixed resistor each define one leg of four legs in a modified wheatstone bridge configuration
Data Source
AI summary
A surgical locator circuit identifies a surgical target such as a kidney stone by disposing an emitter such as a magnetic source behind or adjacent the surgical target, and employing the circuit to identify an axis to the emitter, thus defining an axis or path to the surgical target. An array of sensors arranged in an equidistant, coplanar arrangement each senses a signal indicative of a distance to the emitter. A magneto resistor sensor generates a variable resistance is responsive to the distance to a magnetic coil emitting a magnetic field. An equal signal from each of the coplanar sensors indicates positioning on an axis passing through a point central to the sensors and orthogonal to the plane. A fixed element and signal conditioner augments and normalizes the signal received from each of the sensors to accommodate subtle differences in magneto resistive response among the plurality of sensors.