Biosensor For Label-free Detection Research Articles

Simulation and modeling of high-sensitive JL-TFET based biosensor for label free detection of biomolecules

Simulation and modeling of high-sensitive JL-TFET based biosensor for label free detection of biomolecules

Amorphous IGZO field effect transistor based flexible chemical and biosensors for label free detection

Flexible chemical sensors and biosensors are of interest in different industry sectors and have advantages for being shape-friendly, lightweight, with potential of low cost. The performance factors such as fast response and label free detection makes field effect transistors an attractive platform for such sensors. While there is a large body of literature on ion sensitive field effect transistors using rigid substrates, limited studies are reported on flexible substrates. Electrolytic gated field effect transistors, a class of ion sensitive field effect transistors, have a further advantage as no gate dielectrics are needed (with the electrolytic solution itself acting as the gate dielectric) and need lower operating voltages; there are no reports yet of electrolytic gated field effect transistor with amorphous indium gallium zinc oxide as the semiconductor as well as a sensing layer on flexible substrates and this is the subject of the present work, where fully flexible electrolytic gated field effect transistors are demonstrated on flexible polyethylene terephthalate substrates for pH sensing and for detection of prostate specific antigen. Bottom contact electrolytic gated field effect transistors structures with indium tin oxide as the source and drain were fabricated on flexible polyethylene terephthalate substrates with amorphous indium gallium zinc oxide as the semiconductor deposited over indium tin oxide at room temperature. Materials and electrical characterizations (in a low operating voltage range of −1–1.5 V) were conducted. A pH sensitivity of 20 ± 2 mV pH−1 was demonstrated. Stability studies and bending tests were also conducted. Label-free bio-sensing for prostate specific antigen was demonstrated in the concentration range 1 pg ml−1–10 ng ml−1 in phosphate buffer saline. This learning can be utilized to fabricate wearable sensors for healthcare monitoring at low cost.

Long-Range Surface Plasmon-Polariton Waveguide Biosensors for Human Cardiac Troponin I Detection.

Straight long-range surface plasmon-polariton (LRSPP) waveguides as biosensors for label-free detection are discussed. The sensors consist of 5-μm-wide 35-nm-thick gold stripes embedded in a low-index optical-grade fluoropolymer (CYTOPTM) with fluidic channels etched to the Au surface of the stripes. This work demonstrates the application of the LRSPP biosensors for the detection of human cardiac troponin I (cTnI) protein. cTnI is a biological marker for acute myocardial infarction (AMI), often referred to as a heart attack, which can be diagnosed by elevated levels of cTnI in patient blood. Direct and sandwich assays were developed and demonstrated over the concentration range from 1 to 1000 ng/mL, yielding detection limits of 430 pg/mL for the direct assay and 28 pg/mL for the sandwich assay (1 standard deviation), the latter being physiologically relevant to the early detection or onset of AMI. In addition, a novel approach for data analysis is proposed, where the analyte response is normalized to the response of the antibody layer.

Fabrication of a novel impedimetric biosensor for label free detection of DNA damage induced by doxorubicin

In this work, a novel impedimetric biosensor has been fabricated for detection of DNA damage induced by doxorubicin (DX). Cytochrome P450 reductase (CPR) is required for electron transfer from nicotinamide adenine dinucleotide phosphate (NADPH) to cytochrome P450 (CP450) which causes DX to undergo a one-electron reduction of the p-quinone residue to form the semiquinone radical resulting in the generation of free hydroxyl radical which causes DNA damage. After modification of bare glassy carbon electrode (GCE) with multiwalled carbon nanotubes (MWCNTs) and chitosan (Ch), CPR and CP450 were co-immobilized onto the surface of Ch/MWCNTs/GCE by cross-linking CPR, CP450 and Ch through addition of glutaraldehyde. Then, the DNA was assembled onto the surface of CPRCP450/Ch/MWCNTs/GCE to fabricate the biosensor (DNA/CPRCP450/Ch/MWCNTs/GCE). Modifications applied to the bare GCE to fabricate the biosensor were characterized by CV, EIS and SEM. The DNA/CPRCP450/Ch/MWCNTs/GCE was treated in the damaging solution (DX + NADPH) which caused a significant DNA damage and the exposed DNA bases reduced the electrostatic repulsion of the negatively charged redox probe leading to Faradaic impedance changes. Performance of the biosensor for detection of DNA damage in the presence of Spinach extract was also examined and finally, an indirect impedimetric method was developed for determination of DX.

A dielectrically modulated electrically doped tunnel FET for application of label free biosensor

The fabrication challenges and cost of nanoscale devices have been a major concern in the field of label free biosensor. Therefore, to overcome these issues, we report for the first time a dielectrically modulated electrically doped tunnel field-effect transistor (DM-EDTFET) as a biosensor for label free detection. For this purpose, n+ drain and p+ source regions in proposed device are induced by considering polarity bias of PG-1 = +1.2 V and PG-2 = −1.2, respectively over the ultra-thin silicon body. The proposed structure is immune against doping control issues, avoids thermal budget and fabrication complexity as compared to its counterpart TFET. In DM-EDTFET, a nanogap cavity embedded within the gate dielectric is formed by etching the selected portion of gate dielectric layer towards the source side for sensing the biomolecules. The sensing ability of DM-EDTFET has been analysed in terms of variation in dielectric constant and charge density of biomolecules, and device geometry parameters at different bias conditions. To analyse the relative sensitivity, proposed DM-EDTFET is compared with MOSFET based biosensor in terms of sensing parameters. From these results, DM-EDTFET provides superior results in terms of sensitivity as compared to MOSFET based biosensor. Hence, the proposed DM-EDTFET biosensor can be a promising candidate for the development of future sensing bio-equipments.

A multi-walled carbon nanotube-zinc oxide nanofiber based flexible chemiresistive biosensor for malaria biomarker detection.

We report the fabrication of a flexible, lightweight and disposable multi walled carbon nanotube (MWCNT)-zinc oxide (ZnO) nanofiber based chemiresistive biosensor for label free detection of the malaria biomarker, histidine rich protein II (HRP2). The sensing platform is formed by depositing nanofibers in between the source and drain electrodes patterned on a thin, flexible polyethylene terephthalate (PET) substrate. MWCNT-ZnO nanofibers are synthesized via the electrospinning technique followed by a calcination process. This approach creates functional groups on the nanofiber surface that are used for the one step immobilization of HRP2 antibodies without further surface modification. The device exhibits a good sensitivity of 8.29 kΩ g-1 mL and a wide detection range of 10 fg mL-1-10 ng mL-1, and it is specific towards the targeted HRP2 biomarker. To the best of our knowledge, this is the first report on a flexible chemiresistive biosensor explored for the detection of the malaria biomarker and can be extended in the future to several other biomarker detection systems towards smart point-of-care (POC) diagnostics.

Novel charge plasma based dielectric modulated impact ionization MOSFET as a biosensor for label-free detection

In this paper a charge plasma based dielectric modulated impact ionization MOSFET (CP-DIMOSFET) has been proposed for the first time to ease the label free detection of biomolecules. The concept of CP-DIMOSFET is proposed and analyzed on basis of simulated data using SILVACO ATLAS. Low thermal budgeting and thin silicon layer without any dopant implantations make the proposed structure advantageous compared to the existing MOSFET based biosensors. The results show that the proposed device is capable to detect the presence of biomolecules. Simple fabrication schemes, miniaturization, high sensitivity, dominance of dielectric modulation make the proposed biosensor a promising one that could one day revolutionize the healthcare industry.

Silicon nanograss based impedance biosensor for label free detection of rare metastatic cells among primary cancerous colon cells, suitable for more accurate cancer staging

Detection of rare metastatic cells within a benign tumor is a key challenge to diagnose the cancerous stage of the patients tested by clinical human biopsy or pap smear samples. We have fabricated and tested a nanograssed silicon based bioelectronic device with the ability of detecting a few human colon invasive cancer cells (SW48) in a mixed cell culture of primary cancerous colon cells (HT29) without any biochemical labels. A discernible impedance change was elicited after the presence of 5% metastatic cells in the whole benign sample. The electric field penetration as well as current flow to metastatic cells is different from benign ones due to their different membrane dielectric parameters. Beta dispersion as one of intrinsic bioelectrical properties of the cell membrane in blocking the stimulating current flow in the range of kHz is the specific parameter involved in our diagnosis approach. It can reflect in-depth information about the dielectric properties and the pathological condition of a cell before and after metastatic transformation. Electrically active doped silicon nanograss structures owing to their superior nanocontacts with cell membrane can detect any slight variations in current being originated from the presence of rare metastatic cells on the surface of the sensing electrode. The experimental results revealed that bare doped silicon microelectrodes are incapable of resolving different grades of attached cells.

Biosensors for label free detection based on RF and MEMS technology

A bio-detection method and devices based on RF electric signals and MEMS are proposed and demonstrated by a label free method. We have fabricated a transmission line, an inductive device, and a capacitive device with silicon-based MEMS technology. Main issues are fabrication of devices by MEMS technology, surface modification from hydrophobic to hydrophilic of a benzocyclobutene (BCB) layer by plasma radiation and RF signal measurement before and after bio-processing. The devices made by MEMS technology consist of a BCB polymer and Cu metal patterns on a silicon substrate. Glucose oxidase (GOx) and poly dimethyldiallyl ammonium chloride (PDAC) are used as a biomolecule target and probe. The measured output of power loss is 0.8 dB at 1.9 GHz, and its value is pretty distinguishable from the noise level. From the above-mentioned results, it is clear that the proposed RF method and designs are very effective and powerful as a label free detection system.