Method and apparatus for metal implant contact detection through capacitive measurements
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Publication Number
US-10881298-B2
Publication Date
2021-01-05
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 increases as the main needle is moved through the skin and tissues, then jumps when the main needle makes contact with the metal implant, thus proving the metal implant exists as well as detecting the location of the metal implant. The jump in capacitive measurement is detectable because the area of capacitance has increased from the main needle alone to the main needle plus the surface area of the metal implant. The apparatus can include 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 apparatus enables metal implant contact detection through capacitive measurement using a conductive main needle supported for movement within a housing interior. A portion of the main needle extends through a wall of the housing, and apparatus electronics powered by a battery apply an electrical charge to the main needle as it moves toward or away from a metal implant.
The capacitive measurement is used for detecting a sudden increase in capacitance when the main needle contacts the metal implant. Capacitance changes associated with movement through tissues surrounding the implant are detected as a jump in the measured capacitance when contact occurs, and an output device outputs each of the capacitive measurements for monitoring detection behavior.
The disclosed approach further includes optional reference capacitance measurements to improve positive detection accuracy by comparing reference needle measurements to main-needle capacitance measurements. A reference needle is configured to take a reference capacitance measurement of tissues surrounding the metal implant, and capacitance-measuring software performs measurement collection and detection logic based on sudden capacitance change and threshold behavior.
Claims Coverage
The partial content includes one independent claim and multiple dependent claims that refine the main inventive concept into defined measurement behavior, comparative reference measurements, and particular mechanical and electronic structures. The independent claim covers an apparatus-level capacitive sensing system that applies an electrical charge to a conductive main needle and detects contact by identifying a sudden increase in capacitance, with an output device providing each capacitive measurement.
Conductive main needle capacitive contact detection
An apparatus with a housing and a conductive main needle supported for movement, where apparatus electronics apply an electrical charge to the main needle so capacitive measurements can be taken as the main needle moves toward or away from a metal implant, with detecting a sudden increase in a capacitive measurement when the main needle contacts the metal implant.
Output device for capacitive measurements
An output device in communication with the apparatus electronics configured for outputting each of the capacitive measurements.
Sudden capacitance increase detection limits
A configuration in which the sudden increase in a capacitive measurement occurs in less than one microsecond and up to two picofarads of capacitance.
Reference needle comparative capacitance measurement
A reference needle configured to take reference capacitance measurements such that the apparatus compares reference capacitance measurements to main-needle capacitance measurements and determines implant contact when the measurements match.
Capacitance measurement electronics and software
Capacitance measuring software and a control circuit, including a current source and components for taking capacitance measurement output data, where a capacitive measurement is taken as the main needle moves toward or away from and contacts a metal implant acting as a parallel capacitor.
Reference capacitance of surrounding tissue
A reference needle configured to take a reference capacitance measurement of tissues surrounding the metal implant so the tissue capacitance measurement can be compared to the reference to improve accurate positive detection.
Stabilizer component for slidable main needle
A stabilizer component with a stabilizer opening fitted in a protective cover opening to stabilize the main needle while the main needle remains slidable, with a base wall opening aligned to let the main needle extend through.
Overall claim coverage centers on capacitive contact detection using a conductive main needle with detection of a sudden capacitance increase, supported by outputting each capacitive measurement. Dependent refinements add defined time/capacitance limits for the sudden increase, comparative reference measurements using a reference needle to match tissue capacitance, and additional electronics/software and mechanical stabilization features.
Stated Advantages
Improve accurate positive detection using reference capacitance measurements compared to tissue capacitance measurements.
Documented Applications
Metal implant contact detection through capacitive measurement using a conductive main needle and optional reference needle measurements with output of capacitive measurements.
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