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Field-effect transistors assembled from functionalized carbon nanotubes  [PDF]
Christian Klinke,James B. Hannon,Ali Afzali,Phaedon Avouris
Physics , 2006, DOI: 10.1021/nl052473f
Abstract: We have fabricated field effect transistors from carbon nanotubes using a novel selective placement scheme. We use carbon nanotubes that are covalently bound to molecules containing hydroxamic acid functionality. The functionalized nanotubes bind strongly to basic metal oxide surfaces, but not to silicon dioxide. Upon annealing, the functionalization is removed, restoring the electronic properties of the nanotubes. The devices we have fabricated show excellent electrical characteristics.
One-dimensional Nanomaterials for Field Effect Transistor (FET) Type Biosensor Applications
Mingun Lee,Antonio Lucero,Jiyoung Kim
Transactions on Electrical and Electronic Materials , 2012,
Abstract: One-dimensional, nanomaterial field effect transistors (FET) are promising sensors for bio-molecule detectionapplications. In this paper, we review fabrication and characteristics of 1-D nanomaterial FET type biosensors.Materials such as single wall carbon nanotubes, Si nanowires, metal oxide nanowires and nanotubes, and conductingpolymer nanowires have been widely investigated for biosensors, because of their high sensitivity to bio-substances,with some capable of detecting a single biomolecule. In particular, we focus on three important aspects of biosensors:alignment of nanomaterials for biosensors, surface modification of the nanostructures, and electrical detectionmechanism of the 1-D nanomaterial sensors.
Solution processed large area field effect transistors from dielectrophoreticly aligned arrays of carbon nanotubes  [PDF]
Paul Stokes,Eliot Silbar,Yashira M. Zayas,Saiful I. Khondaker
Physics , 2008, DOI: 10.1063/1.3100197
Abstract: We demonstrate solution processable large area field effect transistors (FETs) from aligned arrays of carbon nanotubes (CNTs). Commercially available, surfactant free CNTs suspended in aqueous solution were aligned between source and drain electrodes using ac dielectrophoresis technique. After removing the metallic nanotubes using electrical breakdown, the devices displayed p-type behavior with on-off ratios up to ~ 2X10^4. The measured field effect mobilities are as high as 123 cm2/Vs, which is three orders of magnitude higher than typical solution processed organic FET devices.
Label-Free Electrical Detection Using Carbon Nanotube-Based Biosensors  [PDF]
Kenzo Maehashi,Kazuhiko Matsumoto
Sensors , 2009, DOI: 10.3390/s90705368
Abstract: Label-free detections of biomolecules have attracted great attention in a lot of life science fields such as genomics, clinical diagnosis and practical pharmacy. In this article, we reviewed amperometric and potentiometric biosensors based on carbon nanotubes (CNTs). In amperometric detections, CNT-modified electrodes were used as working electrodes to significantly enhance electroactive surface area. In contrast, the potentiometric biosensors were based on aptamer-modified CNT field-effect transistors (CNTFETs). Since aptamers are artificial oligonucleotides and thus are smaller than the Debye length, proteins can be detected with high sensitivity. In this review, we discussed on the technology, characteristics and developments for commercialization in label-free CNT-based biosensors.
Electronic Detection of Escherichia coli O157︰H7 Using Single-Walled Carbon Nanotubes Field-Effect Transistor Biosensor  [PDF]
Xiaoxian Zhang, Dongwei Wang, Danna Yang, Sai Li, Zhiqiang Shen
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.410B024
Field effect transistors (FET) based on Single-Walled Carbon Nanotubes (SWNTs) become the hot topic in fields of nano-electronic, clinical diagnostics, environmental testing etc. in recent years. In this paper, we reported a simple, scalable way to enrich semiconducting SWNTs by using HNO3/H2SO4. Then carbon nanotube field-effect transistors (CNTFET) biosensor was fabricated with the enrichment SWNTs for Escherichia coli O157H7 detection. The response of each CNTFET was monitored in real time before and after introduction of the Escherichia coli O157H7 at various concentrations. The results show that CNT-FET biosensors we fabricated are sensitive to change of concentration of solution and response time is really short.
Oxygen and light sensitive field-effect transistors based on ZnO nanoparticles attached to individual double-wall carbon nanotubes  [PDF]
Alina Chanaewa,Beatriz H. Juarez,Horst Weller,Christian Klinke
Physics , 2013, DOI: 10.1039/c1nr11284h
Abstract: The attachment of semiconducting nanoparticles to carbon nanotubes is one of the most challenging subjects in nanotechnology. Successful high coverage attachment and control over the charge transfer mechanism and photo-current generation opens a wide field of new applications such as highly effective solar cells and fibre-enhanced polymers. In this work we study the charge transfer in individual double-wall carbon nanotubes highly covered with uniform ZnO nanoparticles. The synthetic colloidal procedure was chosen to avoid long-chained ligands at the nanoparticle-nanotube interface. The resulting composite material was used as conductive channel in a field effect transistor device and the electrical photo-response was analysed under various conditions. By means of the transfer characteristics we could elucidate the mechanism of charge transfer from non-covalently attached semiconducting nanoparticles to carbon nanotubes. The role of positive charges remaining on the nanoparticles is discussed in terms of a gating effect.
Detecting Lyme Disease Using Antibody-Functionalized Single-Walled Carbon Nanotube Transistors  [PDF]
Mitchell B. Lerner,Jennifer Dailey,Brett R. Goldsmith,Dustin Brisson,A. T. Charlie Johnson
Quantitative Biology , 2013, DOI: 10.1016/j.bios.2013.01.035
Abstract: We examined the potential of antibody-functionalized single-walled carbon nanotube (SWNT) field-effect transistors (FETs) for use as a fast and accurate sensor for a Lyme disease antigen. Biosensors were fabricated on oxidized silicon wafers using chemical vapor deposition grown carbon nanotubes that were functionalized using diazonium salts. Attachment of Borrelia burgdorferi (Lyme) flagellar antibodies to the nanotubes was verified by Atomic Force Microscopy and electronic measurements. A reproducible shift in the turn-off voltage of the semiconducting SWNT FETs was seen upon incubation with Borrelia burgdorferi flagellar antigen, indicative of the nanotube FET being locally gated by the residues of flagellar protein bound to the antibody. This sensor effectively detected antigen in buffer at concentrations as low as 1 ng/ml, and the response varied strongly over a concentration range coinciding with levels of clinical interest. Generalizable binding chemistry gives this biosensing platform the potential to be expanded to monitor other relevant antigens, enabling a multiple vector sensor for Lyme disease. The speed and sensitivity of this biosensor make it an ideal candidate for development as a medical diagnostic test.
Interaction of solid organic acids with carbon nanotube field effect transistors  [PDF]
Christian Klinke,Ali Afzali,Phaedon Avouris
Physics , 2007, DOI: 10.1016/j.cplett.2006.08.090
Abstract: A series of solid organic acids were used to p-dope carbon nanotubes. The extent of doping is shown to be dependent on the pKa value of the acids. Highly fluorinated carboxylic acids and sulfonic acids are very effective in shifting the threshold voltage and making carbon nanotube field effect transistors to be more p-type devices. Weaker acids like phosphonic or hydroxamic acids had less effect. The doping of the devices was accompanied by a reduction of the hysteresis in the transfer characteristics. In-solution doping survives standard fabrication processes and renders p-doped carbon nanotube field effect transistors with good transport characteristics.
Miniature Organic Transistors With Carbon Nanotubes as Quasi-One Dimensional Electrodes  [PDF]
Pengfei Qi,Ali Javey,Marco Rolandi,Qian Wang,Erhan Yenilmez,Hongjie Dai
Physics , 2004,
Abstract: As the dimensions of electronic devices approach those of molecules, the size, geometry and chemical composition of the contact electrodes play increasingly dominant roles in device functions. It is shown here that single-walled carbon nanotubes (SWNT) can be used as quasi one-dimensional (1D) electrodes to construct organic field effect transistors (FET) with molecular scale width (~2 nm) and channel length (1-3 nm). An important feature owing to the quasi 1D electrode geometry is the favorable gate electrostatics that allows for efficient switching of ultra-short organic channels. This affords room temperature conductance modulation by orders of magnitude for organic transistors that are only several-molecules in length, with switching characteristics superior to similar devices with lithographically patterned metal electrodes. With nanotubes, covalent carbon-carbon bonds could be utilized to form contacts to molecular materials. The unique geometrical, physical and chemical properties of carbon nanotube electrodes may lead to various interesting molecular devices.
Protein Biosensors Based on Polymer Nanowires, Carbon Nanotubes and Zinc Oxide Nanorods  [PDF]
Anish Kumar M.,Soyoun Jung,Taeksoo Ji
Sensors , 2011, DOI: 10.3390/s110505087
Abstract: The development of biosensors using electrochemical methods is a promising application in the field of biotechnology. High sensitivity sensors for the bio-detection of proteins have been developed using several kinds of nanomaterials. The performance of the sensors depends on the type of nanostructures with which the biomaterials interact. One dimensional (1-D) structures such as nanowires, nanotubes and nanorods are proven to have high potential for bio-applications. In this paper we review these three different kinds of nanostructures that have attracted much attention at recent times with their great performance as biosensors. Materials such as polymers, carbon and zinc oxide have been widely used for the fabrication of nanostructures because of their enhanced performance in terms of sensitivity, biocompatibility, and ease of preparation. Thus we consider polymer nanowires, carbon nanotubes and zinc oxide nanorods for discussion in this paper. We consider three stages in the development of biosensors: (a) fabrication of biomaterials into nanostructures, (b) alignment of the nanostructures and (c) immobilization of proteins. Two different methods by which the biosensors can be developed at each stage for all the three nanostructures are examined. Finally, we conclude by mentioning some of the major challenges faced by many researchers who seek to fabricate biosensors for real time applications.
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