scholarly journals Instant Mercury Ion Detection in Industrial Waste Water with a Microchip Using Extended Gate Field-Effect Transistors and a Portable Device

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 2209 ◽  
Author(s):  
Revathi Sukesan ◽  
Yi-Ting Chen ◽  
Suman Shahim ◽  
Shin-Li Wang ◽  
Indu Sarangadharan ◽  
...  
Keyword(s):  
Detection Limit ◽  
Inductively Coupled Plasma ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Water Quality Monitoring ◽  
Mercury Ion ◽  
Enhanced Sensitivity ◽  
High Concentrations

Mercury ion selective membrane (Hg-ISM) coated extended gate Field Effect transistors (ISM-FET) were used to manifest a novel methodology for ion-selective sensors based on FET’s, creating ultra-high sensitivity (−36 mV/log [Hg2+]) and outweighing ideal Nernst sensitivity limit (−29.58 mV/log [Hg2+]) for mercury ion. This highly enhanced sensitivity compared with the ion-selective electrode (ISE) (10−7 M) has reduced the limit of detection (10−13 M) of Hg2+ concentration’s magnitude to considerable orders irrespective of the pH of the test solution. Systematical investigation was carried out by modulating sensor design and bias voltage, revealing that higher sensitivity and a lower detection limit can be attained in an adequately stronger electric field. Our sensor has a limit of detection of 10−13 M which is two orders lower than Inductively Coupled Plasma Mass Spectrometry (ICP-MS), having a limit of detection of 10−11 M. The sensitivity and detection limit do not have axiomatic changes under the presence of high concentrations of interfering ions. The technology offers economic and consumer friendly water quality monitoring options intended for homes, offices and industries.

scholarly journals Amine Detection Using Organic Field Effect Transistor Gas Sensors

Sensors ◽  
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.

scholarly journals Combination of Aptamer Amplifier and Antigen-Binding Fragment Probe as a Novel Strategy to Improve Detection Limit of Silicon Nanowire Field-Effect Transistor Immunosensors

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 650
Author(s):  
Cao-An Vu ◽  
Pin-Hsien Pan ◽  
Yuh-Shyong Yang ◽  
Hardy Wai-Hong Chan ◽  
Yoichi Kumada ◽  
...  
Keyword(s):  
Detection Limit ◽  
Ionic Strength ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Limit Of Detection ◽  
Silicon Nanowire ◽  
High Ionic Strength ◽  
Antigen Binding ◽  
Rabbit Igg ◽  
Signal Amplifier

Detecting proteins at low concentrations in high-ionic-strength conditions by silicon nanowire field-effect transistors (SiNWFETs) is severely hindered due to the weakened signal, primarily caused by screening effects. In this study, aptamer as a signal amplifier, which has already been reported by our group, is integrated into SiNWFET immunosensors employing antigen-binding fragments (Fab) as the receptors to improve its detection limit for the first time. The Fab-SiNWFET immunosensors were developed by immobilizing Fab onto Si surfaces modified with either 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA) (Fab/APTES-SiNWFETs), or mixed self-assembled monolayers (mSAMs) of polyethylene glycol (PEG) and GA (Fab/PEG-SiNWFETs), to detect the rabbit IgG at different concentrations in a high-ionic-strength environment (150 mM Bis-Tris Propane) followed by incubation with R18, an aptamer which can specifically target rabbit IgG, for signal enhancement. Empirical results revealed that the signal produced by the sensors with Fab probes was greatly enhanced compared to the ones with whole antibody (Wab) after detecting similar concentrations of rabbit IgG. The Fab/PEG-SiNWFET immunosensors exhibited an especially improved limit of detection to determine the IgG level down to 1 pg/mL, which has not been achieved by the Wab/PEG-SiNWFET immunosensors.

scholarly journals Influence of the Electrolyte Salt Concentration on DNA Detection with Graphene Transistors

Biosensors ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 24
Author(s):  
Agnes Purwidyantri ◽  
Telma Domingues ◽  
Jérôme Borme ◽  
Joana Rafaela Guerreiro ◽  
Andrey Ipatov ◽  
...  
Keyword(s):  
Phosphate Buffer ◽  
Species Interactions ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Limit Of Detection ◽  
Debye Length ◽  
Intermolecular Forces ◽  
Single Layer Graphene ◽  
Dna Adsorption

Liquid-gated Graphene Field-Effect Transistors (GFET) are ultrasensitive bio-detection platforms carrying out the graphene’s exceptional intrinsic functionalities. Buffer and dilution factor are prevalent strategies towards the optimum performance of the GFETs. However, beyond the Debye length (λD), the role of the graphene-electrolytes’ ionic species interactions on the DNA behavior at the nanoscale interface is complicated. We studied the characteristics of the GFETs under different ionic strength, pH, and electrolyte type, e.g., phosphate buffer (PB), and phosphate buffer saline (PBS), in an automatic portable built-in system. The electrostatic gating and charge transfer phenomena were inferred from the field-effect measurements of the Dirac point position in single-layer graphene (SLG) transistors transfer curves. Results denote that λD is not the main factor governing the effective nanoscale screening environment. We observed that the longer λD was not the determining characteristic for sensitivity increment and limit of detection (LoD) as demonstrated by different types and ionic strengths of measuring buffers. In the DNA hybridization study, our findings show the role of the additional salts present in PBS, as compared to PB, in increasing graphene electron mobility, electrostatic shielding, intermolecular forces and DNA adsorption kinetics leading to an improved sensitivity.

scholarly journals Label-Free Split Aptamer Sensor for Femtomolar Detection of Dopamine by Means of Flexible Organic Electrochemical Transistors

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2577 ◽  
Author(s):  
Yuanying Liang ◽  
Ting Guo ◽  
Lei Zhou ◽  
Andreas Offenhäusser ◽  
Dirk Mayer
Keyword(s):  
Detection Limit ◽  
Electrochemical Sensors ◽  
Limit Of Detection ◽  
High Sensitivity ◽  
Label Free ◽  
Dopamine Detection ◽  
Electrochemical Transistor ◽  
Sensitivity And Selectivity

The detection of chemical messenger molecules, such as neurotransmitters in nervous systems, demands high sensitivity to measure small variations, selectivity to eliminate interferences from analogues, and compliant devices to be minimally invasive to soft tissue. Here, an organic electrochemical transistor (OECT) embedded in a flexible polyimide substrate is utilized as transducer to realize a highly sensitive dopamine aptasensor. A split aptamer is tethered to a gold gate electrode and the analyte binding can be detected optionally either via an amperometric or a potentiometric transducer principle. The amperometric sensor can detect dopamine with a limit of detection of 1 μM, while the novel flexible OECT-based biosensor exhibits an ultralow detection limit down to the concentration of 0.5 fM, which is lower than all previously reported electrochemical sensors for dopamine detection. The low detection limit can be attributed to the intrinsic amplification properties of OECTs. Furthermore, a significant response to dopamine inputs among interfering analogues hallmarks the selective detection capabilities of this sensor. The high sensitivity and selectivity, as well as the flexible properties of the OECT-based aptasensor, are promising features for their integration in neuronal probes for the in vitro or in vivo detection of neurochemical signals.

scholarly journals Advances in the fabrication of graphene transistors on flexible substrates

2017 ◽  
Vol 8 ◽  
pp. 467-474 ◽  
Author(s):  
Gabriele Fisichella ◽  
Stella Lo Verso ◽  
Silvestra Di Marco ◽  
Vincenzo Vinciguerra ◽  
Emanuela Schilirò ◽  
...  
Keyword(s):  
Field Effect ◽  
Field Effect Transistors ◽  
High Mobility ◽  
High Sensitivity ◽  
Atomic Layer ◽  
Transparent Electrode ◽  
Large Area ◽  
Sensing Applications ◽  
Dielectric Performance

Graphene is an ideal candidate for next generation applications as a transparent electrode for electronics on plastic due to its flexibility and the conservation of electrical properties upon deformation. More importantly, its field-effect tunable carrier density, high mobility and saturation velocity make it an appealing choice as a channel material for field-effect transistors (FETs) for several potential applications. As an example, properly designed and scaled graphene FETs (Gr-FETs) can be used for flexible high frequency (RF) electronics or for high sensitivity chemical sensors. Miniaturized and flexible Gr-FET sensors would be highly advantageous for current sensors technology for in vivo and in situ applications. In this paper, we report a wafer-scale processing strategy to fabricate arrays of back-gated Gr-FETs on poly(ethylene naphthalate) (PEN) substrates. These devices present a large-area graphene channel fully exposed to the external environment, in order to be suitable for sensing applications, and the channel conductivity is efficiently modulated by a buried gate contact under a thin Al2O3 insulating film. In order to be compatible with the use of the PEN substrate, optimized deposition conditions of the Al2O3 film by plasma-enhanced atomic layer deposition (PE-ALD) at a low temperature (100 °C) have been developed without any relevant degradation of the final dielectric performance.

High sensitivity ultraviolet detection based on three-dimensional graphene field effect transistors decorated with TiO2 NPs

Nanoscale ◽  
2019 ◽  
Vol 11 (31) ◽  
pp. 14912-14920 ◽  
Author(s):  
Shasha Li ◽  
Weijie Yin ◽  
Yuning Li ◽  
Jingye Sun ◽  
Mingqiang Zhu ◽  
...  
Keyword(s):  
Response Time ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Three Dimensional ◽  
High Sensitivity ◽  
Ultraviolet Detection ◽  
Tio2 Nps ◽  
Ultraviolet Photodetectors

Three-dimensional graphene FETs decorated with TiO2 nanoparticles are used as high-sensitivity ultraviolet photodetectors with tunable responsivity and response time.

scholarly journals Reduced Carboxylate Graphene Oxide based Field Effect Transistor as Pb2+ Aptamer Sensor

Micromachines ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 388 ◽  
Author(s):  
Fang Li ◽  
Zhongrong Wang ◽  
Yunfang Jia
Keyword(s):  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Field Effect ◽  
Large Scale ◽  
Field Effect Transistor ◽  
Limit Of Detection ◽  
Binding Model ◽  
Nano Structure ◽  
Effect Transistor

Aptamer functionalized graphene field effect transistor (apta-GFET) is a versatile bio-sensing platform. However, the chemical inertness of graphene is still an obstacle for its large-scale applications and commercialization. In this work, reduced carboxyl-graphene oxide (rGO-COOH) is studied as a self-activated channel material in the screen-printed apta-GFETs for the first time. Examinations are carefully executed using lead-specific-aptamer as a proof-of-concept to demonstrate its functions in accommodating aptamer bio-probes and promoting the sensing reaction. The graphene-state, few-layer nano-structure, plenty of oxygen-containing groups and enhanced LSA immobilization of the rGO-COOH channel film are evidenced by X-ray photoelectron spectroscopy, Raman spectrum, UV-visible absorbance, atomic force microscopy and scanning electron microscope. Based on these characterizations, as well as a site-binding model based on solution-gated field effect transistor (SgFET) working principle, theoretical deductions for rGO-COOH enhanced apta-GFETs’ response are provided. Furthermore, detections for disturbing ions and real samples demonstrate the rGO-COOH channeled apta-GFET has a good specificity, a limit-of-detection of 0.001 ppb, and is in agreement with the conventional inductively coupled plasma mass spectrometry method. In conclusion, the careful examinations demonstrate rGO-COOH is a promising candidate as a self-activated channel material because of its merits of being independent of linking reagents, free from polymer residue and compatible with rapidly developed print-electronic technology.

scholarly journals Heavy metal elements in toiletries analyzed by INAA, ICP-MS and SEM-EDX

2011 ◽  
Vol 1 (1) ◽  
pp. 393-398
Author(s):  
E. Furuta ◽  
H. Minowa ◽  
K. Tagami ◽  
Y. Okada ◽  
H. Nakahara
Keyword(s):  
Heavy Metal ◽  
Detection Limit ◽  
Inductively Coupled Plasma ◽  
Particle Sizes ◽  
Metal Elements ◽  
Inductively Coupled ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
Heavy Metal Elements ◽  
High Concentrations

AbstractRecently, many toiletries claiming inclusion of platinum (Pt), silver (Ag) and gold (Au) as additives are sold in ordinary cosmetics shops. However, their concentrations are not clearly indicated. In the present work, these toiletries were analyzed for heavy metal elements by instrumental neutron activation analysis (INAA) and inductively coupled plasma mass spectrometry (ICP-MS), and the particle sizes were observed by scanning electron microscope (SEM) and the constitutions of the small particles were analyzed by energy dispersive X-ray spectroscopy (EDX). The concentrations of Pt in the toiletries observed were from 1 to 80 ppm. The lower detection limit of Pt by INAA was about 1 ppm because of the presence of sodium in high concentrations for those samples. Consequently, some toiletries which should have had Pt according to the manufactures were found not to contain Pt probably because it was less than the detection limit. On the other hand, there were a few toiletries that were found to contain Ag although the addition of Ag was not mentioned by the manufactures. It is considered that these non-indicated Ag were included as impurities of the added Au. The concentrations of the non-indicated Ag were even higher than those of the indicated Ag. A very small amount of Sr, which was nominated in the negative list of Japan, was also detected in 2 out of 5 kinds of toiletries analyzed by ICP-MS.

Nano-textured high sensitivity ion sensitive field effect transistors

2016 ◽  
Vol 119 (5) ◽  
pp. 054303 ◽  
Author(s):  
M. Hajmirzaheydarali ◽  
M. Sadeghipari ◽  
M. Akbari ◽  
A. Shahsafi ◽  
S. Mohajerzadeh
Keyword(s):  
Field Effect ◽  
Field Effect Transistors ◽  
High Sensitivity
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