Nanomaterial-based
biosensors are a promising fit for portable
and field-deployable diagnosis sensor devices due to their mass production,
miniaturization, and integration capabilities. However, the fabrication
of highly stable and reproducible biosensor devices is challenging.
In this work, we grow a vertically oriented architecture of zinc oxide
nanorods onto the active working area (i.e., the channel between the
source and drain) of a field-effect transistor (FET) using a low-temperature
hydrothermal method. The glucose oxidase enzyme was immobilized on
the zinc oxide nanorod surface by a physical adsorption method to
fabricate the electrolyte-gated FET-based glucose biosensor. The electrical
properties of the electrolyte-gated FET biosensor were measured with
different glucose concentrations. We found a linear increase in current
up to 80 mM glucose concentration with high sensitivity (74.78 μA/mMcm2) and a low detection limit (∼0.05 mM). We illustrate
a highly reproducible fabrication process of zinc oxide nanorod-based
FETs, where vertically grown nanorods with a higher surface-to-volume
ratio enhance the enzyme immobilization, provide a microenvironment
for longer enzyme activity, and translate to better glucose sensing
parameters. Additionally, our electrolyte-gated FET biosensor showed
promising application in freshly drawn mouse blood samples. These
findings suggest a great opportunity to translate into practical high-performance
biosensors for a broad range of analytes.