Resistive and Capacitive γ-Ray Dosimeters Based On Triggered Depolymerization in Carbon Nanotube Composites

Abstract

We report γ-ray dosimeters using carbon nanotubes wrapped with metastable poly(olefin sulfone)s (POSs) that readily depolymerize when exposed to ionizing radiation. New POSs, designed for wrapping single-walled carbon nanotubes (SWCNTs), are synthesized and characterized. The resulting POS-SWCNT composites serve as the active transducer in a novel class of γ-ray dosimeters. In our devices, polymer degradation results in immediate changes in the electronic potential of the POS-SWCNT active layers by decreasing the electron tunneling barriers between individualized tubes and by creating enhanced cofacial π-π electron contacts. By incorporating the SWCNT-POS composites into small resistive device platforms, we establish a rare example of real-time detection and dosimetry of radioactive ionizing radiation using organic-based materials. We show that the sensitivity of our platform closely depends on the intrinsic stability of the polymer matrix, the opacity toward γ-rays, and the dispersion efficiency (i.e., the individualization and isolation of the individual SWCNT charge carriers). Resistance decreases up to 65% after irradiation with a 40 krad dose demonstrates the high sensitivity of this novel class of γ-ray sensors. In addition, the detection mechanism was evaluated using a commercial capacitive device platform. The ease of fabrication and low power consumption of these small and inexpensive sensor platforms combined with appealing sensitivity parameters establishes the potential of the poly(olefin sulfone)-SWCNT composites to serve as a new transduction material in γ-ray sensor applications.

High‐Performance and Radiation‐Hard Carbon Nanotube Complementary Static Random‐Access Memory

“…Mater. 2019, 5,1900313 www.advelectronicmat.de reduce the influence of polymer on the radiation-harden properties of CNTs, [46] the film was annealed in a tube furnace with a forming gas (Ar/H 2 : 5/1) at a temperature of 600 °C for 3 h to remove polymer. [6] Fabrication of CMOS FETs and SRAM Cells: The source and drain electrodes were patterned by electron beam lithography, followed by evaporation of 0.3 nm Ti and 70 nm Pd to fabricate a p-type contact and 60 nm Sc and 10 nm Al to fabricate an n-type contact.…”

“…The Si/SiO 2 substrate was immersed in the diluted solution for 72 h. The substrate was then taken out of the solution, rinsed with toluene for 30 min and purged with 99.999% N 2 and baked at 120 °C for 30 min at atmosphere. Finally, in order to reduce the influence of polymer on the radiation‐harden properties of CNTs, the film was annealed in a tube furnace with a forming gas (Ar/H 2 : 5/1) at a temperature of 600 °C for 3 h to remove polymer …”

Carbon Nanotube Chemical Sensors

“…74 and Zeininger et al . 75 used CNTs wrapped by poly(olefin sulfone) (POS) polymers to detect ionizing radiation. Upon exposure to radiation, the meta-stable POS spontaneously depolymerizes with fragmentation resulting in an increase in the interconnections between CNTs and overall CNT network conductivity.…”

Protein‐facilitated gold nanoparticle formation as indicators of ionizing radiation

“…Although these systems determine radiation exposure with high sensitivity, their high effective atomic numbers make them unsuitable for patient dosimetry (Çelik, Çevik, Bacaksiz, & Çelik, ). Carbon nanotube‐based detectors have been investigated for the detection of ionizing radiation but suffer from lack of sensitivity towards therapeutic levels of ionizing radiation (Zeininger, He, Hobson, & Swager, ). Quantum dots have shown high scintillation properties, but current synthesis techniques result in batch‐to‐batch variation making them difficult to use for dosimetry (Lecavalier, Goulet, Allen, Beaulieu, & Larivière, ; Yang & Tuan, ).…”