Handheld readout system for field‐effect transistor biosensor arrays for label‐free detection of biomolecules

Abstract

Sensors for label‐free biomolecule detection using ion‐sensitive field‐effect transistor (ISFET) arrays working in a liquid environment offer great opportunities for fast diagnostics of diseases and other point‐of‐care applications. In the last decades, ISFET‐based sensors with progressively improved sensitivity, robustness, and diversity of detected biomolecules were described. However, a reliable, miniaturized electronic readout for such sensors is one of the main demands in the field. In this work, we developed a handheld readout system for biomolecule sensing with ISFET arrays, which can measure four channels simultaneously and can be used for a wide range of ISFET devices from microsized ISFETs to silicon nanowire transistor arrays. The hardware was built around a 32‐bit PIC microcontroller. A user‐friendly software written in LabVIEW communicates with the hardware to record and to display the measurement results. After a simple calibration, the error of the handheld system was below 5% in comparison with a standard semiconductor parameter analyzer. For the first applications, pH sensing and deoxyribonucleic acid (DNA) immobilization and hybridization events were successfully measured with our ISFET sensors. Our readout system in combination with our top‐down fabricated sensor devices has the potential to bring the ISFET sensors closer to the point‐of‐care testing in near future.