Needle-type field-effect transistor based on carbon nanotube derivative without lithography process

Nanoneedle Transistor-Based Sensors for the Selective Detection of Intracellular Calcium Ions

“…18 The tip-end of the nanopipette was immersed in swCNT solution (0.5 mg/mL in 1,2-dichlorobenzene) for 1 min and dried at room temperature for 1 day, where swCNTs were adsorbed onto the glass surface at the end of the nanopipette, connecting the two electrodes (1Figure 1A-iii). 8 Previous reports show that CNTs in nonpolar solvent were physisorbed onto a polar surface (e.g., glass) via weak interaction forces such as van der Waals and dipole induced dipole interactions. 19À21 Then, the swCNT-connected network junction was immersed in the solution of 100 μM Fluo-4-AM in dimethyl sulfoxide (DMSO) for 30 min (Figure 1A-iv), where Fluo-4-AM dye molecules strongly bound to the swCNTs on the probe by πÀπ stacking between the surface of swCNTs and the benzene ring of Fluo-4-AM.…”

“…In this process, the metal was deposited separately onto both sides of the clean nanopipette surface by rotating the nanopipette by 180° around the axis (Figure A-ii and detailed experimental procedure in Supporting Information). The tip-end of the nanopipette was immersed in swCNT solution (0.5 mg/mL in 1,2-dichlorobenzene) for 1 min and dried at room temperature for 1 day, where swCNTs were adsorbed onto the glass surface at the end of the nanopipette, connecting the two electrodes (Figure A-iii) . Previous reports show that CNTs in nonpolar solvent were physisorbed onto a polar surface ( e.g ., glass) via weak interaction forces such as van der Waals and dipole induced dipole interactions. − Then, the swCNT-connected network junction was immersed in the solution of 100 μM Fluo-4-AM in dimethyl sulfoxide (DMSO) for 30 min (Figure A-iv), where Fluo-4-AM dye molecules strongly bound to the swCNTs on the probe by π–π stacking between the surface of swCNTs and the benzene ring of Fluo-4-AM. , Previously, Fluo-4-AM dye molecules have been utilized as a fluorescence indicator for calcium ions because they reversibly bind to calcium ions and emit a fluorescence light .…”

“…7À13 For example, several research groups utilized fluorophore-labeled atomic force microscopy (AFM) tips or quantum dots to acquire information inside of a living cell via fluorescence imaging. 7,8 Also, other researchers successfully monitored the intracellular electric potential using nanowire-based transistor devices. 13 However, previous nanoprobe devices still exhibited rather low performance in detecting specific intracellular molecules in terms of its selectivity and sensitivity.…”

“…Recently, field effect transistor (FET)-type biosensors based on single-walled carbon nanotubes (swCNTs) and nanowires have attracted much attention because of their excellent selectivity and real-time response for the detection of bio- and chemical molecules. − However, most of these biosensors have a rather large size compared with that of individual cells and could not be placed inside a cell for the selective detection of intracellular biomolecular species. On the other hand, nanoscale probes such as patch clamps have been extensively utilized to detect the signals inside a cell for various applications such as the clinical test and the dynamic study of neural systems. − For example, several research groups utilized fluorophore-labeled atomic force microscopy (AFM) tips or quantum dots to acquire information inside of a living cell via fluorescence imaging. , Also, other researchers successfully monitored the intracellular electric potential using nanowire-based transistor devices . However, previous nanoprobe devices still exhibited rather low performance in detecting specific intracellular molecules in terms of its selectivity and sensitivity.…”

Electrical Probing of Submicroliter Liquid Using Graphene Strip Transistors Built on a Nanopipette

“…However, the detection normally requires a significant quantity of analyte solution due to the fact that the lateral size of the fabricated transistor devices is large. Since nanoscale probes like patch clamps have been widely used to detect the signals from a localized environment, such as inside a cell or intercellular space,17–19 more and more efforts have been devoted to developing nanoscale or probe‐type FETs for space‐localized detection 20, 21. Herein, we demonstrate that chemical‐vapor‐deposited graphene sheets can be transferred onto a glass nanopipette to form graphene strips, which can be connected at the probe end to form a transistor channel.…”