A MEMS (Micro-Electro-Mechanical System) microdosimeter is a miniaturized device designed to measure and quantify ionizing radiation exposure. Ionizing radiation includes particles and electromagnetic waves that have enough energy to remove tightly bound electrons from atoms, creating ions and potentially causing biological damage. MEMS microdosimeters are utilized in various applications, including radiation protection, medical imaging, space exploration, and environmental monitoring.
Here's how a typical MEMS microdosimeter for radiation detection operates:
Microfabrication: The device is manufactured using microfabrication techniques commonly employed in the semiconductor industry. This involves etching, deposition, and patterning processes to create intricate structures on a silicon substrate.
Sensing Element: The core of the microdosimeter is its sensing element, which is designed to capture the effects of ionizing radiation. This sensing element is often a micro-sized capacitor with a dielectric material positioned between two conductive plates. The dielectric material can be sensitive to radiation, causing changes in its properties upon exposure.
Charging and Discharging: When the microdosimeter is exposed to ionizing radiation, radiation particles interact with the sensing element's dielectric material, causing the material's electrical properties to change. This might involve the creation of charge carriers (ions or electrons) within the dielectric, altering its permittivity and other electrical characteristics.
Capacitance Change: The change in the dielectric properties leads to a change in the capacitance of the sensing element. The capacitance is a measure of the device's ability to store electric charge. The alteration in capacitance is proportional to the radiation dose received by the device.
Electronics and Readout: The changes in capacitance are detected and processed by integrated electronics within the MEMS microdosimeter. These electronics may include amplification, analog-to-digital conversion, and signal conditioning components. The resulting digital signal represents the radiation dose that the microdosimeter has been exposed to.
Calibration: Before being used for radiation measurements, the MEMS microdosimeter needs to be calibrated. This involves subjecting the device to known radiation doses and correlating the changes in capacitance to those doses. Calibration ensures accurate and reliable measurement of radiation exposure.
Data Collection and Analysis: The digital output from the MEMS microdosimeter is collected and can be further analyzed. Depending on the application, the data might be used for real-time monitoring, historical dose tracking, or as part of a larger radiation safety system.
Integration: MEMS microdosimeters can be integrated into various systems, such as wearable devices, portable radiation monitors, medical instruments, and even spacecraft. Their small size and low power consumption make them suitable for applications where traditional radiation detection methods might be impractical.
Overall, MEMS microdosimeters offer advantages such as miniaturization, lower power consumption, and the potential for integration into various devices and systems, making them valuable tools for radiation detection and monitoring in a wide range of contexts.