Banca de QUALIFICAÇÃO: JULIAN ÉVELIN ALVES VARJÃO

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE: JULIAN ÉVELIN ALVES VARJÃO
DATA: 15/12/2025
HORA: 08:30
LOCAL: Auditório do PPGQ
TÍTULO: Novel and cost-effective solid-state fabrication of portable electrochemical sensors through graphite/toner composite coupled to a roll-to-roll laminating machine.
PALAVRAS-CHAVES: solid state manufacturing, roll to roll, toner-based, 3-Nitro-L-Tyrosine, electrochemical detection.
PÁGINAS: 25
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
SUBÁREA: Química Analítica
ESPECIALIDADE: Eletroanalítica
RESUMO:

The solid-state fabrication of electrochemical sensors is an efficient strategy for developing new, low-cost miniaturized devices. This approach does not require solvents, eliminating drying steps, reducing waste, and enabling large-scale production. In this work, we present two approaches for manufacturing portable, low-cost devices. The first demonstrates improved reproducibility and charge-transfer kinetics in large-scale, pencil-drawn three-electrode electrochemical systems produced using an adapted 3D printer.The performance of the devices was evaluated in the presence of the redox probe [Fe(CN)₆]^{3-/ 4-}, where the voltammograms obtained showed improvement in repeatability (RSD 28.8% to 4.4%) and reproducibility (RSD 24% to 2.8%) in relation to the peak potential variation (ΔEp), with an average ΔEp of 300 mV to 144 mV for the systems subjected to heat treatment. The second approach involves manufacturing electrodes by roll-to-roll dry deposition of a mixture of graphite powder and printer toner.The devices produced showed good electrochemical performance, with an average ΔEp of 271 mV (RSD = 8%) and an optimal peak current (Ipa) of 106.10 µA (RSD = 9%) (n = 10). In addition, they exhibited good electrochemical kinetics (k° = 1.47 × 10^-3 cm s^-1) and a low charge-transfer resistance of 0.553 ± 0.01 kΩ. Finally, the toner/graphite-based electrochemical system was chosen because it is a faster and easier manufacturing method for use in the detection of 3-Nitro-L-Tyrosine (3-NLT), an important biomarker of oxidative/nitrative stress in the body, with a detection limit of 0.53 mmol L^-1, demonstrating the reliability and applicability of the proposed methodology.

MEMBROS DA BANCA:
Presidente - 1998602 - EVERSON THIAGO SANTOS GERONCIO DA SILVA
Interno - 794.***.***-87 - REGINALDO DA SILVA SANTOS - UESPI
Externo ao Programa - 2549060 - CARLA EIRAS
Externo à Instituição - 368.***.***-18 - LÍVIA FLORIO SGOBBI - UFG
Externo à Instituição - 027.***.***-64 - REJANE MARIA PEREIRA DA SILVA - UESPI