title: Optimization of urea-EnFET based on Ta2O5 layer with post annealing.
abstract: In this study, the urea-enzymatic field effect transistors (EnFETs) were investigated based on pH-ion sensitive field effect transistors (ISFETs) with tantalum pentoxide (Ta(2)O(5)) sensing membranes. In addition, a post N(2) annealing was used to improve the sensing properties. At first, the pH sensitivity, hysteresis, drift, and light induced drift of the ISFETs were evaluated. After the covalent bonding process and urease immobilization, the urea sensitivity of the EnFETs were also investigated and compared with the conventional Si(3)N(4) sensing layer. The ISFETs and EnFETs with annealed Ta(2)O(5) sensing membranes showed the best responses, including the highest pH sensitivity (56.9 mV/pH, from pH 2 to pH 12) and also corresponded to the highest urea sensitivity (61 mV/pC(urea), from 1 mM to 7.5 mM). Besides, the non-ideal factors of pH hysteresis, time drift, and light induced drift of the annealed samples were also lower than the controlled Ta(2)O(5) and Si(3)N(4) sensing membranes.
authors.affiliation: Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1 st road, Kwei-Shan, Tao-Yuan, 333, Taiwan. yolue411@gmail.com
authors.forename: Cheng-En
authors.initials: CE
authors.lastname: Lue
authors.forename: Ting-Chun
authors.initials: TC
authors.lastname: Yu
authors.forename: Chia-Ming
authors.initials: CM
authors.lastname: Yang
authors.forename: Dorota G
authors.initials: DG
authors.lastname: Pijanowska
authors.forename: Chao-Sung
authors.initials: CS
authors.lastname: Lai
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D010087:Oxides / Q000737:chemistry; D013635:Tantalum / Q000737:chemistry; D014173:Transistors, Electronic; D014508:Urea / Q000737:chemistry*; D014510:Urease / Q000737:chemistry / Q000378:metabolism
chemical_list: D004800:Enzymes, Immobilized; D010087:Oxides; D013635:Tantalum; D014508:Urea; D014510:Urease; C078151:tantalum oxide