Method and apparatus for metal implant contact detection through capacitive measurements
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Publication Number
US-10638931-B2
Publication Date
2020-05-05
Expiration Date
Abstract
A method and apparatus for metal implant contact detection through capacitive measurements is provided. Capacitive measurement is accomplished with a conductive wire/lead, for example a main needle. The measured capacitance as the main needle is moved through the skin and tissues increases, then jumps when the main needle makes contact with the metal implant, thus proving the metal implant exists and the location of the metal implant. The jump in capacitive measurement is detectable because the area of capacitance has gone from the main needle to the main needle plus the surface area of the metal implant surface area. The apparatus may also have a reference needle for taking reference needle capacitive measurements in the tissues surrounding the metal implant to increase the accuracy during use of the apparatus. A housing is provided for supporting the main and reference needles and supporting or housing apparatus electronics.
Core Innovation
The patent describes a battery-powered capacitance measuring apparatus and method for metal implant contact detection through capacitive measurements. A main needle is supported by a housing and is moved toward or away from the metal implant while taking a capacitive measurement, with detection of a sudden increase in capacitance when the main needle contacts the metal implant.
The detected behavior is described as a capacitance measurement that increases gradually as the main needle moves through skin or tissue, followed by a detectable sudden jump when contact with the metal implant occurs. The sudden jump is attributed to an increased capacitance area including the main needle and the metal implant surface, and the apparatus provides an output device in communication with the apparatus electronics to output the capacitive measurements.
To improve positive detection accuracy, the patent describes an embodiment using a reference needle that takes a reference capacitive measurement of tissues around the metal implant. The method compares a main needle capacitance measurement to the reference capacitance measurement, and capacitance-measuring software rejects gradual changes and focuses on detecting the sudden increase associated with metal implant contact.
The patent further describes an apparatus structure and electronics for performing capacitance measurement. The housing defines a housing interior and includes openings and components such as a stabilizer component and a gasket with a protective cover, while electronics include a current source, a CTMU module, an analog-to-digital converter, and a multiplexer used with circuit capacitors and switch capacitors to implement capacitance-to-digital conversion and output generation, including options for wired or wireless monitoring.
Claims Coverage
Independent claim clm-00001 covers a battery-powered housing apparatus implementing a capacitive measurement method with a conductive main needle to detect metal implant contact by detecting a sudden increase in measured capacitance and outputting the capacitive measurements. The dependent claims specify time and magnitude constraints for the sudden increase, relate the magnitude to implant size, and add a reference needle with comparison for improved positive detection accuracy, plus additional apparatus electronics and metal contact connections for paired main and reference measurements.
Sudden capacitive increase on main needle contact
Taking a capacitive measurement as the main needle moves toward or away from the metal implant and detecting a sudden increase in a capacitance measurement when the main needle contacts the metal implant.
Battery-powered housing with outputting capacitive measurements
Providing a housing that defines a housing interior, providing a battery in the housing interior, providing apparatus electronics powered by the battery, providing a main needle in communication with the apparatus electronics, and outputting the capacitive measurements to an output device.
Time and capacitance magnitude constraints for the sudden increase
A sudden increase in the measured capacitance occurs in less than one microsecond and up to two picofarads of capacitance.
Sudden increase magnitude dependent on implant size
The increased capacitance measurement depends on the size of the metal implant, with a larger implant causing a larger sudden increase in capacitance measurement.
Reference needle reference capacitance comparison to improve positive detection
Using a reference needle to take a reference capacitive measurement of tissues around a metal implant and comparing it with the main needle capacitive measurement to improve accurate positive detection of the metal implant by comparing capacitance values.
Capacitance-measuring software and control electronics for measurement output data
Providing capacitance-measuring software and control circuitry including a current source, a CTMU module, and an analog-to-digital converter with a multiplexer wired to a circuit capacitor and a switch capacitor to collect capacitive measurements and generate display output data as the main needle moves toward or away from a metal implant and contacts it.
Metal contacts for main and reference needle capacitance and reference capacitance
Providing metal contacts connected to a main needle and to a reference needle so capacitance and reference capacitance are measured and compared to determine whether a metal implant is present.
Across the independent and dependent claims, the inventive focus is on detecting a sudden increase in capacitance when a main needle contacts a metal implant within a battery-powered housed system, outputting the measurement data, and improving detection accuracy by comparing the main needle measurement with a reference needle measurement of tissue capacitance while using specified capacitance-measurement electronics and paired main and reference metal contact connections.
Stated Advantages
Improves accurate positive detection of the metal implant by comparing main and reference capacitance measurements.
Documented Applications
Metal implant contact detection through capacitive measurements using a battery-powered apparatus and a main needle, with optional reference needle comparison for improved positive detection accuracy.
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