Auxiliary Antenna Array for Surgical Foreign Object Detection
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Solution Overview
Problem
Conventional RFID systems for detecting foreign objects in patients after surgery are not entirely reliable due to limitations in signal reception from small, low-frequency RFID tags, which require multiple scans and varying antenna orientations, and are ineffective for non-metallic objects.
Innovation Solution
An auxiliary antenna array is integrated into a mattress pad on the operating table, comprising pairs of toroidal antennae and associated electronics, which enhances the system's ability to receive RFID signals from tagged objects, regardless of orientation or patient size, using a hand-held transducer with both transmitting and receiving antennae.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional RFID systems use small, low-frequency tags for detecting foreign objects, then the system is non-invasive and can detect both metallic and non-metallic objects, but the signal reception is unreliable and requires multiple scans with varying orientations
Solution Approach 1:
The patent divides the detection system into multiple receiving antennas arranged in a specific geometric pattern (e.g., orthogonal pairs or tetrahedral configurations) rather than using a single antenna. This segmentation allows the system to detect RFID tags from multiple orientations simultaneously, eliminating the need for repeated scanning and improving detection reliability while maintaining the non-invasive low-frequency approach
Solution Approach 2:
The patent transitions from a single-point or linear antenna arrangement to a three-dimensional spatial array of receiving antennas. This dimensional expansion creates multiple reception pathways for RFID signals regardless of tag orientation, solving the reliability issue without requiring higher frequencies that would increase patient exposure to harmful radiation
2Reliability
If multiple scans with varying orientations are performed to improve detection reliability, then the detection success rate increases, but the scanning time and complexity increase
Solution Approach 1:
The patent pre-positions multiple receiving antennas in fixed spatial arrangements before the scanning process begins. This preliminary configuration ensures that regardless of how the RFID tag is oriented during scanning, at least one antenna will be optimally positioned to receive the signal, eliminating the need for repeated scans with manual orientation changes and significantly reducing scanning time
3Length of stationary object
If the RFID tag frequency is increased to improve signal strength, then the detection range increases, but signal attenuation due to water and soft tissue increases
Solution Approach 1:
The patent introduces multiple receiving antennas as intermediary detection points between the transmitting antenna and the RFID tag. By distributing multiple reception points throughout the scanning volume, the system increases the probability that at least one intermediary antenna will be in an optimal position to receive weak signals from deeply embedded or poorly oriented tags, effectively extending detection range without increasing signal frequency or patient exposure
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 configuration significantly improves the detection success rate of foreign objects by allowing reliable signal reception from RFID tags in a single pass, reducing the need for multiple scans and varying orientations, and effectively detecting both metallic and non-metallic objects.
Implementation Method 1
RFID tags emit a radio frequency signal when excited by electromagnetic energy from a transmitting antenna
Implementation Method 2
The emitted signal is received by a receiving antenna and processed by a computer
Implementation Method 3
signal attenuation due to water and soft tissue in the body is inversely dependant upon the frequency of the signal
Data Source
AI summary
The apparatus includes a hand-held RF transducer having a transmit section for providing an energizing signal to cause a RFID tag associated with an object retained in the body of the patient to transmit an RF signal and a receiver section for receiving the RF signal transmitted by the RFID tag, as the patient's body is scanned. An auxiliary antenna array for receiving the transmitted RF signal transmitted by the RFID tag is situated in the mattress on the operating table under the patient. Signal processing electronics are connected to the receiver section of the transducer and to the auxiliary antenna array for determining and indicating when a RF signal from a tag has been received, representing that a tagged object remains in the body of the patient, and for decoding the RF signal to identify the object.