Transistor com porta eletrolítica aplicado como sensor de radiação ionizante

Abstract

Electrolyte-gated transistor (EGT) make up a class of devices frequently applied as sensors and biosensors due to their ability to operate with high current density under low voltage applications. This work focuses on investigating the radiation sensing capability through the EGT platform, using two polymer gels as radiation-sensitive materials (electrolytic dielectrics) that have already been studied in the literature. One of them is the MAGIC-f polymer gel (from English, Methacrylic and Ascorbic acid in Gelatin Initiated by Copper with formaldehyde), which has been studied from the perspective of its optical properties, as well as its variation in optical spectrum when exposed to different doses of ionizing radiation. However, its application in transistors to investigate electrical properties is still novel, a subject not yet explored in the scientific literature in the field. The other gel will be the ionic gel [EMIM][TFSI], which already has its potential defined in EGTs, and will now be researched for its radiation sensitivity. Current scientific literature presents many EGT works focused on sensing; however, it lacks works dedicated to the development of EGTs for ionizing radiation sensing. For device development, a glass substrate with interdigitated source and drain electrodes made of ITO was used, along with another glass substrate with interdigitated gold electrodes. Both devices will have a gold gate electrode, which will be in contact with the gels. The channel is composed of the semiconducting polymer poly(3-hexylthiophene-2,5-diyl) (P3HT). The gels were irradiated separately from the transistors and only deposited on the devices at the moment of electrical characterization. Since the transistors are signal amplifying and multiparametric devices, the focus of this work was on the qualification of parameters extracted from the EGTs using MAGIC-f and ionic gel [EMIM][TFSI] as electrolytic dielectrics when exposed, and not exposed, to ionizing radiation. Typical EGT curves and comparisons between extracted parameters are the quantifiers of this dosimeter proposal. Unpublished results using MAGIC-f as electrolyte were obtained, proving that the gel has electrical characteristics suitable for application in EGTs. Furthermore, measurements taken from EGTs with irradiated and non-irradiated ionic gel, when analyzed in pairs, showed differences between them, indicating that irradiation of the gel causes changes in its electronic conduction properties. These results show that the EGT platform has the potential to be studied and applied in the area of dosimetry.