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.

On the Use of Scalable NanoISFET Arrays of Silicon with Highly Reproducible Sensor Performance for Biosensor Applications

“… 54 − 57 It is documented that ISFETs with bare SiO 2 surfaces exhibit a sensor response on the order of 34 mV/pH, which may increase up to 45 mV/pH with the modification of the oxide surface with functional molecules such as APTES. 56 High-throughput clinical analysis of novel bioassays is critical to the development of label-free IVD and other related applications where a closely knit sensor response from a high-density sensor platform such as the nanoISFET arrays of Si realized in this work may provide an appropriate platform. Although high-performance and precise sensor characteristics were achieved, we took a closer look at the different factors that may be playing a role in the tiny variations of the pH response from nanoISFET arrays, which will be investigated and rectified in further work (see Supporting Information ).…”

“…Going a step further toward the application of such sensor platforms for point-of-care (PoC) applications, we connected our nanoISFET arrays to a portable hand-held readout system for field-effect-based biosensor arrays which was recently developed in our group. 56 Figure 6 A shows the photograph of this portable measurement setup where the sensor chip is mounted on a PCB and connected to the four-channel miniaturized readout system built around a 32 bit PIC microcontroller and equipped with a user-friendly readout software designed in LabView communicating with the hardware to record and display the electrical measurements on a computer screen or any other device. The sensor chip is also equipped with a fluidic layer to facilitate pH sensor measurements in real time for longer periods.…”

Biologically sensitive field-effect transistors: from ISFETs to NanoFETs

“…Such advanced read-out systems with DC and AC measurement capabilities in combination with different nanoscale devices might have the potential to bring nanowire FET sensors closer to PoC applications in the near future [ 45 ].…”

High Aspect Ratio Fin-Ion Sensitive Field Effect Transistor: Compromises toward Better Electrochemical Biosensing

“…The shift of the surface potential Ψ0 was evaluated from the flat band voltage calculating the minimum of the first derivative of the transfer curves at different electrolyte pH values (details of the procedure to Nernst limit is ̴ 59 mV/pH) [37,38] . In our case this could be due to defects introduced during the growth of the sensing oxide since we could not use a dedicated chamber for the process.…”