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A novel inverter-based digital floating-gate MOSFET sensor design for commercial X-ray dosimetry is presented. The biomedical healthcare industry sterilizes blood products for storage purposes using Gamma and X-ray radiations. This requires an ultra-low-power dosimeter that ensures irradiation does not exceed the maximum allowable 50 Gy while providing the required minimum levels of 25 Gy. In this work, minimum-sized MOS transistor devices are employed in an inverter configuration, eliminating the continuous flow of current and reducing power consumption significantly. Maximum measured currents, which flow only during the transition period, are in the nA range, compared to continuous currents of conventional sensor designs in the μA range. Final measured results show the viability of the proposed design for radiation dosimetry applications.

Advancements in the medical industry are some of the key contributions of the scientific community. One related direction of research is the X-ray sterilization of blood that is stored for future use. Currently, the tags used to indicate the irradiation level of the blood rely on visual indicators rather than an automated method. As a result, the irradiation levels of the blood cannot be ascertained. This paper proposes a new wireless dosimeter tag to measure the radiation levels with sufficient precision so as to avoid any material wastage and costs. The tag relies on an RF tag which consists of a CMOS transmitter, energy harvesting component and an off-chip inkjet printed antenna. In this paper, using 0.13 μm CMOS technology a floating gate MOSFET dosimeter design and an off-chip inkjet printed antenna are presented. These two components are the basic building blocks of the complete wireless dosimeter system. The floating gate MOSFET design is studied for its pre and post-radiation performance. The measured results show how the difference in the device current can be used for the radiation dose measurements. For the antenna, a printed antenna with suitable shielding is employed to enhance its radiation performance in the dissipative blood environment. The measured radiation pattern shows adequate gain and back-lobe radiation characteristics, thus making the surroundings invisible to the antenna and best suited for the intended application.