Chemical-free and scalable process for the fabrication of a uniform array of liquid-gated CNTFET, evaluated by KCl electrolyte

AbstractBiosensors based on liquid-gated carbon nanotubes field-effect transistors (LG-CNTFETs) have attracted considerable attention, as they offer high sensitivity and selectivity; quick response and label-free detection. However, their practical applications are limited due to the numerous fabrication challenges including resist-based lithography, in which after the lithography process, the resist leaves trace level contaminations over the CNTs that affect the performance of the fabricated biosensors. Here, we report the realization of LG-CNTFET devices using silicon shadow mask-based chemical-free lithography process on a 3-in. silicon wafer, yielding 21 sensor chips. Each sensor chip consists of 3 × 3 array of LG-CNTFET devices. Field emission scanning electron microscope (FESEM) and Raman mapping confirm the isolation of devices within the array chip having 9 individual devices. A reference electrode (Ag/AgCl) is used to demonstrate the uniformity of sensing performances among the fabricated LG-CNTFET devices in an array using different KCl molar solutions. The average threshold voltage (Vth) for all 9 devices varies from 0.46 to 0.19 V for 0.1 mM to 1 M KCl concentration range. This developed chemical-free process of LG-CNTFET array fabrication is simple, inexpensive, rapid having a commercial scope and thus opens a new realm of scalable realization of various biosensors.

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Bifunctional Nanoparticles as a Recyclable Fluorescent Sensor for pH and Cu2+ Detection and Removal of Heavy Metal Ions

NANO ◽

10.1142/s1793292020500484 ◽

2020 ◽

Vol 15 (04) ◽

pp. 2050048

Author(s):

Yong Qian ◽

Xiangfu Meng ◽

Hongji Liu ◽

Xingyu Wang ◽

Hui Wang

Keyword(s):

Aqueous Solution ◽

Heavy Metal Ions ◽

High Efficiency ◽

Fluorescent Sensor ◽

High Sensitivity ◽

Label Free ◽

Practical Applications ◽

Surrounding Environment ◽

Label Free Detection ◽

Recyclable Adsorbent

Magnetic and fluorescent-based sensors have demonstrated widely applications due to their easily recycle and quickly optical response. However, the complex synthesis and weaker function of these sensors limit their practical applications. Herein, an unmodified, magnetic-functionalized carbon dots-based fluorescent sensor has been developed for label-free detection of pH and Cu[Formula: see text] with high sensitivity. The sensors can not only reversibly quench and recover the fluorescence signals in response to the variation of surrounding environment including pH and Cu[Formula: see text], but also be used as a high-efficiency recyclable adsorbent for removing Cu[Formula: see text], Hg[Formula: see text], Cr[Formula: see text] and Pb[Formula: see text] from aqueous solution.

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Exonuclease III assisted and label-free detection of mercury ion based on toehold strand displacement amplification strategy

Analytical Methods ◽

10.1039/c6ay02169g ◽

2016 ◽

Vol 8 (39) ◽

pp. 7054-7060 ◽

Cited By ~ 5

Author(s):

Lili Yu ◽

Hui Xu ◽

Hou Chen ◽

Liangjiu Bai ◽

Wenxiang Wang

Keyword(s):

High Sensitivity ◽

Mercury Ion ◽

Fluorometric Assay ◽

Label Free ◽

Strand Displacement ◽

Strand Displacement Amplification ◽

Exonuclease Iii ◽

Label Free Detection ◽

Sensitivity And Selectivity ◽

Amplification Strategy

A label-free, exonuclease III assisted Hg2+ fluorometric assay based on strand displacement amplification was developed with high sensitivity and selectivity.

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Phosphate-dependent DNA Immobilization on Hafnium Oxide for Bio-Sensing Applications

MRS Proceedings ◽

10.1557/proc-1191-oo12-04 ◽

2009 ◽

Vol 1191 ◽

Cited By ~ 2

Author(s):

Nicholas M Fahrenkopf ◽

Serge Oktyabrsky ◽

Eric Eisenbraun ◽

Magnus Bergkvist ◽

Hua Shi ◽

...

Keyword(s):

Nucleic Acid ◽

Hafnium Oxide ◽

Dielectric Material ◽

Field Effect Transistors ◽

Leading Edge ◽

High Sensitivity ◽

Cmos Technology ◽

Label Free ◽

Sensing Applications ◽

Label Free Detection

AbstractHafnium(IV) oxide (HfO2) has replaced silicon oxide as a gate dielectric material in leading edge CMOS technology, providing significant improvement in gate performance for field effect transistors (FETs). We are currently exploring this high-k dielectric for its use in nucleic acid-based FET biosensors. Due to its intrinsic negative charge, label-free detection of DNA can be achieved in the gate region of high-sensitivity FET devices. Previous work has shown that phosphates and phosphonates coordinate specifically onto metal oxide substrates including aluminum and titanium oxides. This property can therefore be exploited for direct immobilization of biomolecules such as nucleic acids. Our work demonstrates that 5’ phosphate-terminated single stranded DNA (ssDNA) can be directly immobilized onto HfO2 surfaces, without the need for additional chemical modification or crosslinking. Non-phosphorylated ssDNA does not form stable surface interactions with HfO2, indicating that immobilization is dependent upon the 5’ terminal phosphate. Further work has shown that surface immobilized ssDNA can be hybridized to complementary target DNA and that sequence-based hybridization specificity is preserved. These results suggest that the direct DNA-HfO2 immobilization strategy can enable nucleic acid-based biosensing assays on HfO2 terminated surfaces. This work will further enable high sensitivity electrical detection of biological targets utilizing transistor-based technologies.

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Amine Detection Using Organic Field Effect Transistor Gas Sensors

Sensors ◽

10.3390/s21010013 ◽

2020 ◽

Vol 21 (1) ◽

pp. 13

Author(s):

Panagiotis Mougkogiannis ◽

Michael Turner ◽

Krishna Persaud

Keyword(s):

Low Power ◽

Gas Sensors ◽

Field Effect ◽

Field Effect Transistors ◽

Limit Of Detection ◽

High Sensitivity ◽

Organic Field Effect Transistors ◽

Practical Applications ◽

Empirical Prediction ◽

Sensitivity And Selectivity

Low power gas sensors with high sensitivity and selectivity are desired for many practical applications. Devices based on organic field effect transistors are promising because they can be fabricated at modest cost and are low power devices. Organic field effect transistors fabricated in bottom-gate bottom-contact configuration using the organic semiconductor [2,5-(2-octyldodecyl)-3,6-diketopyrrolopyrrole-alt-5,5-(2,5-di(thien-2-yl)thieno] [3,2-b]thiophene) (DPP-T-TT) were systematically investigated to determine the response characteristics to a series of alkylamines and ammonia. The highest sensitivity was to dibutylamine with a limit of detection of 0.025 ppb, followed by n-butylamine, 0.056 ppb, and ammonia, 2.17 ppb. A model was constructed based on the Antoine equation that successfully allows the empirical prediction of the sensitivity and selectivity of the gas sensor to various analytes including amines and alcohols based on the Antoine C parameter and the heat of the vaporization of the analyte.

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Optical Sensing of Microbial Life on Surfaces

Applied and Environmental Microbiology ◽

10.1128/aem.03001-15 ◽

2015 ◽

Vol 82 (5) ◽

pp. 1362-1371 ◽

Cited By ~ 14

Author(s):

M. Fischer ◽

G. J. Triggs ◽

T. F. Krauss

Keyword(s):

Basic Research ◽

High Sensitivity ◽

Natural Environments ◽

Label Free ◽

Biofilm Growth ◽

Microbial Cells ◽

Industrial Facilities ◽

Label Free Detection ◽

Sensitivity And Selectivity ◽

The Many

ABSTRACTThe label-free detection of microbial cells attached to a surface is an active field of research. The field is driven by the need to understand and control the growth of biofilms in a number of applications, including basic research in natural environments, industrial facilities, and clinical devices, to name a few. Despite significant progress in the ability to monitor the growth of biofilms and related living cells, the sensitivity and selectivity of such sensors are still a challenge. We believe that among the many different technologies available for monitoring biofilm growth, optical techniques are the most promising, as they afford direct imaging and offer high sensitivity and specificity. Furthermore, as each technique offers different insights into the biofilm growth mechanism, our analysis allows us to provide an overview of the biological processes at play. In addition, we use a set of key parameters to compare state-of-the-art techniques in the field, including a critical assessment of each method, to identify the most promising types of sensors. We highlight the challenges that need to be overcome to improve the characteristics of current biofilm sensor technologies and indicate where further developments are required. In addition, we provide guidelines for selecting a suitable sensor for detecting microbial cells on a surface.

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Affinity Sensors for the Diagnosis of COVID-19

Micromachines ◽

10.3390/mi12040390 ◽

2021 ◽

Vol 12 (4) ◽

pp. 390

Author(s):

Maryia Drobysh ◽

Almira Ramanaviciene ◽

Roman Viter ◽

Arunas Ramanavicius

Keyword(s):

Field Effect Transistors ◽

Resonance Field ◽

Analytical Signal ◽

Nucleic Acid Hybridization ◽

Detection Methods ◽

Label Free ◽

Infected People ◽

Label Free Detection ◽

Main Instrument ◽

Antigen Antibody

The coronavirus disease 2019 (COVID-19) outbreak caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was proclaimed a global pandemic in March 2020. Reducing the dissemination rate, in particular by tracking the infected people and their contacts, is the main instrument against infection spreading. Therefore, the creation and implementation of fast, reliable and responsive methods suitable for the diagnosis of COVID-19 are required. These needs can be fulfilled using affinity sensors, which differ in applied detection methods and markers that are generating analytical signals. Recently, nucleic acid hybridization, antigen-antibody interaction, and change of reactive oxygen species (ROS) level are mostly used for the generation of analytical signals, which can be accurately measured by electrochemical, optical, surface plasmon resonance, field-effect transistors, and some other methods and transducers. Electrochemical biosensors are the most consistent with the general trend towards, acceleration, and simplification of the bioanalytical process. These biosensors mostly are based on the determination of antigen-antibody interaction and are robust, sensitive, accurate, and sometimes enable label-free detection of an analyte. Along with the specification of biosensors, we also provide a brief overview of generally used testing techniques, and the description of the structure, life cycle and immune host response to SARS-CoV-2, and some deeper details of analytical signal detection principles.

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Biologically sensitive field-effect transistors: from ISFETs to NanoFETs

Essays in Biochemistry ◽

10.1042/ebc20150009 ◽

2016 ◽

Vol 60 (1) ◽

pp. 81-90 ◽

Cited By ~ 45

Author(s):

Vivek Pachauri ◽

Sven Ingebrandt

Keyword(s):

Field Effect ◽

Gate Dielectric ◽

Gate Dielectrics ◽

Field Effect Transistors ◽

Silicon Nanowire ◽

Label Free ◽

Biomolecular Detection ◽

New Device ◽

Label Free Detection ◽

History Of

Biologically sensitive field-effect transistors (BioFETs) are one of the most abundant classes of electronic sensors for biomolecular detection. Most of the time these sensors are realized as classical ion-sensitive field-effect transistors (ISFETs) having non-metallized gate dielectrics facing an electrolyte solution. In ISFETs, a semiconductor material is used as the active transducer element covered by a gate dielectric layer which is electronically sensitive to the (bio-)chemical changes that occur on its surface. This review will provide a brief overview of the history of ISFET biosensors with general operation concepts and sensing mechanisms. We also discuss silicon nanowire-based ISFETs (SiNW FETs) as the modern nanoscale version of classical ISFETs, as well as strategies to functionalize them with biologically sensitive layers. We include in our discussion other ISFET types based on nanomaterials such as carbon nanotubes, metal oxides and so on. The latest examples of highly sensitive label-free detection of deoxyribonucleic acid (DNA) molecules using SiNW FETs and single-cell recordings for drug screening and other applications of ISFETs will be highlighted. Finally, we suggest new device platforms and newly developed, miniaturized read-out tools with multichannel potentiometric and impedimetric measurement capabilities for future biomedical applications.

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Photonic crystals: A platform for label-free and enhanced fluorescence biomolecular and cellular assays

MRS Proceedings ◽

10.1557/proc-1133-aa04-01 ◽

2008 ◽

Vol 1133 ◽

Author(s):

Brian T. Cunningham ◽

Leo Chan ◽

Patrick C. Mathias ◽

Nikhil Ganesh ◽

Sherine George ◽

...

Keyword(s):

Photonic Crystal ◽

Photonic Crystals ◽

High Throughput Screening ◽

High Sensitivity ◽

Excitation Wavelength ◽

Label Free ◽

Crystal Surfaces ◽

Enhanced Fluorescence ◽

Preferred Direction ◽

Label Free Detection

Abstract Photonic crystal surfaces represent a class of resonant optical structures that are capable of supporting high intensity electromagnetic standing waves with near-field and far-field properties that can be exploited for high sensitivity detection of biomolecules and cells. While modulation of the resonant wavelength of a photonic crystal by the dielectric permittivity of adsorbed biomaterials enables label-free detection, the resonance can also be tuned to coincide with the excitation wavelength of common fluorescent tags - including organic molecules and semiconductor quantum dots. Photonic crystals are also capable of efficiently channeling fluorescent emission into a preferred direction for enhanced extraction efficiency. Photonic crystals can be designed to support multiple resonant modes that can perform label free detection, enhanced fluorescence excitation, and enhanced fluorescence extraction simultaneously on the same device. Because photonic crystal surfaces may be inexpensively produced over large surface areas by nanoreplica molding processes, they can be incorporated into disposable labware for applications such as pharmaceutical high throughput screening. In this talk, the optical properties of surface photonic crystals will be reviewed and several applications will be described, including results from screening a 200,000-member chemical compound library for inhibitors of protein-DNA interactions, gene expression microarrays, and high sensitivity of protein biomarkers.

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Label-free DNA detection based on oligonucleotide-stabilized silver nanoclusters and exonuclease III-catalyzed target recycling amplification

Analytical Methods ◽

10.1039/c4ay00838c ◽

2014 ◽

Vol 6 (15) ◽

pp. 6082-6087 ◽

Cited By ~ 6

Author(s):

Hui Ma ◽

Wei Wei ◽

Qian Lu ◽

Zhixin Zhou ◽

Henan Li ◽

...

Keyword(s):

High Sensitivity ◽

Silver Nanoclusters ◽

Label Free ◽

Exonuclease Iii ◽

Target Recycling ◽

Free Dna ◽

Sensitivity And Selectivity ◽

Exo Iii ◽

Ag Ncs ◽

Recycling Amplification

A label-free DNA biosensor with high sensitivity and selectivity is constructed by using DNA–Ag NCs and Exo III-catalyzed target recycling amplification.

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