Detection principles of biological and chemical FET sensors.

Dual-gate field-effect biosensors (bioFETs) with asymmetric gate capacitances were shown to surpass the Nernst limit of 59 mV/pH. However, previous studies have conflicting findings on the effect of the capacitive amplification scheme on the sensor detection limit, which is inversely proportional to the signal-to-noise ratio (SNR). Here, we present a systematic experimental investigation of the SNR using ultrathin silicon transistors. Our sensors operate at low voltage and feature asymmetric front and back oxide capacitances with asymmetry factors of 1.4 and 2.3. We demonstrate that in the dual-gate configuration, the response of our bioFETs to the pH change increases proportional to the asymmetry factor and indeed exceeds the Nernst limit. Further, our results reveal that the noise amplitude also increases in proportion to the asymmetry factor. We establish that the commensurate increase of the noise amplitude originates from the intrinsic low-frequency characteristic of the sensor noise, dominated by nu...

Experimental Study of the Detection Limit in Dual-Gate Biosensors Using Ultrathin Silicon Transistors.

https://www.mdpi.com/2079-6374/11/4/103/pdf

Recent Advances of Field-Effect Transistor Technology for Infectious Diseases

Lab-on-Chip is a technology that aims to transform the Point-of-Care (PoC) diagnostics field; nonetheless a commercial production compatible technology is yet to be established. Lab-on-Printed Circuit Board (Lab-on-PCB) is currently considered as a promising candidate technology for cost-aware but simultaneously high specification applications, requiring multi-component microsystem implementations, due to its inherent compatibility with electronics and the long-standing industrial manufacturing basis. In this work, we demonstrate the first electrolyte gated field-effect transistor (FET) DNA biosensor implemented on commercially fabricated PCB in a planar layout. Graphene ink was drop-casted to form the transistor channel and PNA probes were immobilized on the graphene channel, enabling label-free DNA detection. It is shown that the sensor can selectively detect the complementary DNA sequence, following a fully inkjet-printing compatible manufacturing process. The results demonstrate the potential for the effortless integration of FET sensors into Lab-on-PCB diagnostic platforms, paving the way for even higher sensitivity quantification than the current Lab-on-PCB state-of-the-art of passive electrode electrochemical sensing. The substitution of such biosensors with our presented FET structures, promises further reduction of the time-to-result in microsystems combining sequential DNA amplification and detection modules to few minutes, since much fewer amplification cycles are required even for low-abundance nucleic acid targets.

/pdf/printable-graphene-biofets-for-dna-quantification-in-lab-on-18cg68cv7l.pdf

Printable graphene BioFETs for DNA quantification in Lab-on-PCB microsystems

CMOS (complementary metal oxide semiconductor) biosensors are promising to provide label-free and highly sensitive detection with high throughput. Ion-sensitive field effect transistors (ISFETs) can sensitively detect the charges carried by target analyte upon specific binding. This work studies the hybridization of complementary DNA (deoxyribonucleic acid) strands by ISFETs implemented in a $0.35-\mu $ m CMOS process. Three designs of different electrode and transistor sizes are implemented, with pH sensitivities measured between 27 to 32 mV/pH in terms of the threshold voltage shift. The increase of current in the p-type ISFETs due to hybridized target DNA molecules is successfully detected near femtomolar concentration, which is among the best sensing resolution for CMOS ISFETs.

CMOS Ion Sensitive Field Effect Transistors for Highly Sensitive Detection of DNA Hybridization

A dual-gate ion-sensitive field-effect transistor (DGFET) with the back-side sensing structure implemented in a 0.18 μm SOI-CMOS SoC platform realizing high performance bioelectrical detection with non-ideal effect reduction is presented. Non-ideal effects of the conventional ISFET, such as time drift and hysteresis, are suppressed by the innovative scheme in DGFET using the bottom poly-gate (PG) transistor instead of the fluidic gate (FG) transistor for sensing. As a result, the signal-to-noise ratio (SNR) is improved by 155x, time drift is reduced by 53x, and hysteresis is reduced by 3.7x. For certain applications which require high sensitivity, a pulse-modulated biasing technique can be adopted to effectively reduce time drift with high pH sensitivity of 453 mV/pH which is ∼7.5x enhancement over the Nernst limit in the proposed DGFET.

High performance dual-gate ISFET with non-ideal effect reduction schemes in a SOI-CMOS bioelectrical SoC

The invention describes a fluid kit and an operating method The fluid kit includes a substrate having a plurality of contact pads designed to be electrically connected to the analyzer, a semiconductor chip having a sensor array and a reference electrode The fluid kit includes a first fluid channel having an inlet and connected to a second fluid channel, the first fluid channel is aligned to thesecond fluid channel such that the sensor array and the reference electrode are disposed within the second fluid channel A first plug is arranged at the first inlet, and comprises a flexible materialconfigured to be passed through by the capillary without leakage of the fluid through the first plug The invention further provides an analyzer for analyzing the fluid

Kit for fluid analysis and analyzer

A CMOS-based ion-sensitive field-effect transistor (ISFET) is designed, fabricated, and validated as a biosensor for protein diagnosis. Utilizing 180 nm foundry process, this work experimentally demonstrates the developed dual-gated ISFET biosensor array (128 by 128 devices) has capabilities to obtain statistical measurements of pH. Furthermore, it can be used to detect several specific biomarkers, i.e. cTnI, HbA1c and HBV-DNA, for cardiac diseases, diabetes and hepatitis B respectively. This work shows benefits of the nano-scale ISFET array for biosensing applications.

A sub-micron CMOS-based ISFET array for biomolecular sensing

An integrated circuit includes a plurality of sensing pixels. Each sensing pixel of the plurality of sensing pixels includes a sensing film portion, a potential-sensing device configured to generate a first signal responsive to an electrical characteristic of the sensing film portion, a temperature-sensing device configured to generate a second signal responsive to a temperature of the sensing film portion, and one or more heating elements configured to adjust the temperature of the sensing film portion.

Integrated circuit having temperature-sensing device

Es werden eine Fluidikpatrone und Verfahren fur deren Betrieb beschrieben. Die Fluidikpatrone weist ein Substrat mit einer Vielzahl von Kontakt-Pads, die so konfiguriert sind, dass sie sich mit einem Analysator elektrisch verbinden, einen Halbleiterchip mit einem Sensor-Array und eine Referenz-Elektrode auf. Die Fluidikpatrone weist einen ersten Fluidikkanal auf, der einen Einlass hat und mit einem zweiten Fluidikkanal verbunden ist, wobei der zweite Fluidikkanal so ausgerichtet ist, dass das Sensor-Array und die Referenz-Elektrode in dem zweiten Fluidikkanal angeordnet sind. Ein erster Stopfen ist an dem ersten Einlass angeordnet. Der erste Stopfen weist ein nachgiebiges Material auf, das so konfiguriert ist, dass es von einer Kapillare durchstochen wird, ohne dass Flussigkeit durch den ersten Stopfen durchsickert.

Chin-Hua Wen

Papers

High performance dual-gate ISFET with non-ideal effect reduction schemes in a SOI-CMOS bioelectrical SoC

Kit for fluid analysis and analyzer

A sub-micron CMOS-based ISFET array for biomolecular sensing

Integrated circuit having temperature-sensing device

Patrone und Analysator für die Analyse von Fluiden