Chipless Wireless Sensor Tag for Radiation Sterilization Monitoring
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Solution Overview
Problem
Current methods for monitoring gamma radiation sterilization in pharmaceutical packaging are inadequate due to their cost, sensitivity to environmental conditions, and inability to provide real-time, non-invasive, and accurate dosage measurements, leading to potential under- or over-exposure of medical devices.
Innovation Solution
A low-cost, chipless, and wireless radiation sensor using a PEDOT:PSS/PU composite material with scalable printing technologies, operating in a differential configuration, which detects gamma radiation exposure up to 40 kGy and can be read from a distance, enabling real-time monitoring and quality control of medical devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional radiation monitoring methods (radiochromic films, thermoluminescent dosimeters, semiconductor dosimeters) are used, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the radiation sensing function from complex electronic dosimeters and implements it using a simple printed resonant circuit tag. The sensor uses a microstrip resonator with radiation-sensitive material that directly converts gamma radiation exposure into measurable impedance changes, eliminating the need for batteries, chips, and complex electronics while maintaining measurement capability
Solution Approach 2:
The patent employs a low-cost printed sensor tag that can be disposed of after single use. The sensor is manufactured using inexpensive printing techniques on flexible substrates, making it economically viable for single-use applications where the sensor is attached to packaging and discarded after sterilization monitoring, eliminating the need for expensive reusable electronic dosimeters
2Reliability
If electronic wireless dosimeters are used, then real-time monitoring capability is improved, but reliability under radiation exposure deteriorates due to energy dependence and temperature sensitivity
Solution Approach 1:
The sensor tag is completely passive and self-service, requiring no external power source or active electronics. It utilizes the incident gamma radiation itself to induce current in the resonant circuit, which then backscatters the interrogating signal with a frequency shift proportional to the accumulated dose. This passive operation ensures reliability under radiation exposure while enabling real-time monitoring through wireless interrogation
Solution Approach 2:
The patent replaces electronic measurement systems with a passive electromagnetic resonance-based system. Instead of using active electronic dosimeters that require power and are sensitive to radiation and temperature, the invention uses a passive resonant circuit whose resonant frequency naturally shifts in response to radiation-induced changes in the radiation-sensitive material's electrical properties
3Ease of manufacture
If colorimetric dosimeters are used, then cost is reduced, but measurement precision deteriorates due to requirement of visual inspection
Solution Approach 1:
The patent replaces visual inspection methods with wireless electromagnetic interrogation. Instead of requiring manual visual assessment of color changes in colorimetric films, the invention uses a resonant circuit tag that wirelessly transmits quantitative dosage information through frequency shifts, enabling automated, precise, and remote monitoring while maintaining low manufacturing costs through printing techniques
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
The sensor provides accurate, real-time monitoring of gamma radiation exposure, ensuring proper sterilization of medical devices by detecting changes in impedance and amplitude shifts, thus preventing under- or over-exposure and enhancing quality control in medical device sterilization processes.
Implementation Method 1
A low-cost, chipless, and wireless radiation sensor using a PEDOT:PSS/PU composite material... which detects gamma radiation exposure up to 40 kGy... The sensor provides accurate, real-time monitoring of gamma radiation exposure, ensuring proper sterilization of medical devices by detecting changes in impedance and amplitude shifts
Data Source
AI summary
A system may receive a package previously irradiated for sterilization. The package may have a sensor comprising a reference tag and sensing tag at least partially coated with a material comprising poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and Polyurethan (PU). The system may scan the sensing tag and the reference tag. The system may determine, based on radio frequency (RF) signals reflected from the sensing tag and reference tag, the sensor is exposed to radiation. The system may output a quality measure indicative of the sensor being exposed to radiation.