Lateral SOI BJT Radiation Dosimeter for Real-Time Dose Monitoring
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Solution Overview
Problem
Current radiation monitoring technologies, such as ionization detectors and TLDs, lack real-time dose rate measurement capabilities, which is critical for immediate assessment of radiation exposure in emergency situations like a 'dirty' bomb detonation or nuclear crisis, and existing large-scale detectors are not designed for individual exposure monitoring.
Innovation Solution
A semiconductor-based radiation dosimeter using a lateral silicon-on-insulator (SOI) bipolar junction transistor (BJT) with a buried insulator layer that traps positive charges from ionizing radiation, allowing for real-time determination of radiation exposure by measuring changes in collector current and current gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ionization detectors or Geiger counters are used, then real-time dose rate measurement is available, but the devices are relatively expensive and complex
Solution Approach 1:
The patent extracts the radiation detection function from complex electronic readout systems and implements it using a simple semiconductor device with charge traps. The lateral SOI BJT structure inherently provides radiation detection through charge accumulation in the buried oxide layer, eliminating the need for complex ionization chambers or Geiger-Müller tubes while maintaining real-time measurement capability.
Solution Approach 2:
The patent employs a semiconductor-based dosimeter that can be manufactured using standard CMOS fabrication processes, making it inexpensive and potentially disposable. The device uses readily available semiconductor materials and fabrication techniques, contrasting with the expensive and complex ionization detectors, enabling widespread deployment for real-time radiation monitoring.
2Device complexity
If TLDs are used, then the devices are relatively inexpensive, but real-time readout is not available and processing requires specialized equipment
Solution Approach 1:
The lateral SOI BJT dosimeter is electrically self-readable through standard transistor electrical characterization. The device structure includes built-in electrical contacts that allow direct measurement of electrical properties (current, voltage, capacitance) that change with radiation exposure, eliminating the need for external specialized TLD readers and enabling immediate readout without delayed processing.
Solution Approach 2:
The patent replaces the thermal reading mechanism of TLDs with electrical measurement of the semiconductor device. Instead of heating the dosimeter to release trapped charges and measure light emission, the system uses electrical characterization of the lateral SOI BJT, substituting a simple electrical measurement system for complex thermal-optical reading equipment.
3Area of stationary object
If large-scale detectors are deployed for area monitoring, then radiation exposure levels can be determined, but individual exposure monitoring capability is lost
Solution Approach 1:
The patent divides radiation monitoring into numerous small, independent lateral SOI BJT dosimeters that can be individually assigned to specific persons or locations. Each device is self-contained and provides independent measurement, allowing both individual wearability and area-wide deployment through distributed placement, thus achieving both individual and area monitoring simultaneously.
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
Enables real-time and long-term tracking of radiation doses, providing immediate exposure information for effective triage and treatment decisions, and can be integrated into various devices or implanted in patients for continuous monitoring.
Implementation Method 1
The buried insulator layer comprises a plurality of charge traps. When the radiation dosimeter is exposed to radiation, positive charge is trapped in the plurality of charge traps in the buried insulator layer
Implementation Method 2
determining a change in one of the collector current and current gain of the radiation dosimeter; and determining an amount of the radiation dose based on the change in one of the collector current and current gain
Data Source
AI summary
A radiation dosimeter includes a semiconductor substrate and a buried insulator layer disposed on the semiconductor substrate. The buried insulator layer has a plurality of charge traps. A semiconductor layer is disposed on the buried insulator layer. The semiconductor layer has an emitter, an intrinsic base, and a collector laterally arranged with respect to one another. In response to radiation exposure by the radiation dosimeter, positive charges are trapped in the plurality of charge traps in the buried insulator layer, the amount of positive charge trapped being used to determine the amount of radiation exposure. A method for radiation dosimetry includes providing a radiation dosimeter, where the radiation dosimeter includes a lateral silicon-on-insulator bipolar junction transistor having a buried insulator layer; exposing the radiation dosimeter to ionizing radiation; determining a change in one of the collector current and current gain of the radiation dosimeter; and determining an amount of the radiation dose based on the change in one of the collector current and current gain.