AVS 65th International Symposium & Exhibition
    Thin Films Division Thursday Sessions
       Session TF+AS+EL+EM+NS+PS+SS-ThA

Paper TF+AS+EL+EM+NS+PS+SS-ThA8
Functionalization of Indium Gallium Zinc Oxide Surfaces for Transparent Biosensors

Thursday, October 25, 2018, 4:40 pm, Room 104B

Session: IoT Session: Thin Films for Flexible Electronics and IoT
Presenter: Gregory Herman, Oregon State University
Authors: X. Du, Oregon State University
S. John, Oregon State University
J. Bergevin, Oregon State University
G.S. Herman, Oregon State University
Correspondent: Click to Email
Amorphous indium gallium zinc oxide (IGZO) field effect transistors (FETs) are a promising technology for a wide range of electronic applications including implantable and wearable biosensors. We have recently evaluated the functionalization of IGZO back channel surfaces with a range of self-assembled monolayers (SAM) to precisely control surface chemistry and improve stability of the IGZO-FETs. The SAMs evaluated include, n-hexylphosphonic acid (n-HPA), (3,3,4,4,5,5,6,6,6-nonafluorohexyl) phosphonic acid (FPA), and (3-aminopropyl) trimethoxysilane (APTMS). A comparison of the surface chemistry is made for bare and SAM functionalized IGZO back channel surfaces using X-ray photoelectron spectroscopy and electronic device measurements in air and phosphate buffer solution (PBS). We find significantly improved device stability with the SAMs attached to the IGZO back channel surface, both in air and PBS. We related this to the reduction of traps at the back channel surface due to SAM passivation. To further evaluate the IGZO-FETs as biosensors we have immobilized glucose oxidase (GOx) to the APTMS functionalized IGZO back channel surface using glutaraldehyde. We find that both the FPA functionalized and the GOx immobilized surfaces are effective for the detection of glucose in PBS. Furthermore, the GOx immobilized IGZO-FET based glucose sensors have excellent selectivity to glucose, and can effectively minimize interference from acetaminophen/ascorbic acid. Finally, we will discuss fully transparent IGZO-FET based glucose sensors that have been fabricated directly on transparent catheters.These results suggest that IGZO-FETs may provide a means to integrate fully transparent, highly-sensitive sensors into contact lenses.