Patternable Nanowire Sensors for Electrochemical Recording of Dopamine
ABSTRACT Spatially resolved electrochemical recording of neurochemicals is difficult due to the challenges associated with producing nanometer-scale patternable and integrated sensors. We describe the lithographic fabrication and characterization of patternable gold (Au) nanowire (NW) based sensors for the electrochemical recording of dopamine (DA). We demonstrate a straightforward NW-size-independent approach to align contact pads to NWs. Sensors, with NW widths as small as 30 nm, exhibited considerable insensitivity to scan rates during cyclic voltammetry, a nonlinear increase in oxidation current with increasing NW width, and the selectivity to measure submaximal synaptic concentrations of DA in the presence of interfering ascorbic acid. The electrochemical sensitivity of Au NW electrode sensors was much larger than that of Au thin-film electrodes. In chronoamperometric measurements, the NW sensors were found to be sensitive for submicromolar concentration of DA. Hence, the patternable NW sensors represent an attractive platform for electrochemical sensing and recording.
Full-textDOI: · Available from: Pawan Tyagi, May 04, 2015
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- "Several components of a TJMD, electrodes and molecules in the exposed regions, can interact with one or more chemicals or biochemicals . Utilization of Au as one of the metal electrode may enable a TJMD to do electrochemistry based neurochemical sensing . Utilization of molecule as sensing element can be used to target the miniscule amounts of hazardous molecules. "
ABSTRACT: Molecule based devices may govern the advancement of the next generation’s logic and memory devices. Molecules have the potential to be unmatched device elements as chemists can mass produce an endless variety of molecules with novel optical, magnetic, and charge transport characteristics. However, the biggest challenge is to connect two metal leads to a target molecule(s) and develop a robust and versatile device fabrication technology that can be adopted for commercial scale mass production. This paper discusses distinct advantages of utilizing commercially successful tunnel junctions as a vehicle for developing molecular spintronics devices. We describe the use of a prefabricated tunnel junction with the exposed sides as a testbed for molecular device fabrication. On the exposed sides of a tunnel junction molecules are bridged across an insulator by chemically bonding with the two metal electrodes; sequential growth of metal-insulator-metal layers ensures that separation between two metal electrodes is controlled by the insulator thickness to the molecular device length scale. This paper highlights various attributes of tunnel junction based molecular devices with ferromagnetic electrodes for making molecular spintronics devices. We strongly emphasize a need for close collaboration between chemists and magnetic tunnel junction researchers. Such partnerships will have a strong potential to develop tunnel junction based molecular devices for the futuristic areas such as memory devices, magnetic metamaterials, and high sensitivity multi-chemical biosensors etc.Nano brief reports and reviews 10/2015; 10(04):150106234821002. DOI:10.1142/S1793292015300029 · 1.09 Impact Factor
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- "Nano-gap was bridged by the molecule and gold nanoparticle assembly. Schematic design adopted from ref.  molecules were successfully bridged across a GaAs spacer. According to I-V studies at 4.2 K, OPV molecules significantly increased the charge transport rate. "
ABSTRACT: Advancement of molecular devices will critically depend on the approach to establish electrical connections to the functional molecule(s). We produced a molecular device strategy which is based on chemically attaching of molecules between the two magnetic/nonmagnetic metallic electrodes along the multilayer edge(s) of a prefabricated tunnel junction. Here, we present the fabrication methodology for producing these multilayer edge molecular electronics/spintronics devices (MEMEDs/MEMSDs) and details of the associated challenges and their solutions. The key highlight of our MEMED/MEMSD approach is the method of producing exposed side edge(s) of a tunnel junction for hosting molecular conduction channels by a simple liftoff method. The liftoff method ensured that along the tunnel junction edges, the minimum gap between the two metal electrodes equaled the thickness of the tunnel barrier. All of the tunnel junction test beds used a ~2 nm alumina (AlOx) tunnel barrier. We successfully bridged the magnetic organometallic molecular clusters and non-magnetic alkane molecules across the AlOx insulator along the exposed edges, to transform the prefabricated tunnel junction into the molecular electronics or spintronics devices. Tunnel junction test beds were fabricated with a variety of metal electrodes, such as NiFe, Co, Ni, Au, Ta, Cu and Si. Stability of ultrathin thin AlOx varied with the type of bottom metal electrodes used for making MEMED/MEMSD. Additionally, molecular solution used for bridging molecular channels in a MEMED was not compatible with all the metal electrodes; molecular solution resistant ferromagnetic electrodes were developed for the fabrication of MEMSDs. MEMSD approach offers an open platform to test virtually any combination of magnetic electrodes and magnetic molecules, including single molecular magnets.
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ABSTRACT: Nanowires with a rough surface texture show unusual electronic, optical, and chemical properties; however, there are only a few existing methods for producing these nanowires. Here, we describe two methods for growing both free standing and lithographically patterned gold (Au) nanowires with a rough surface texture. The first strategy is based on the deposition of nanowires from a silver (Ag)–Au plating solution mixture that precipitates an Ag–Au cyanide complex during electrodeposition at low current densities. This complex disperses in the plating solution, thereby altering the nanowire growth to yield a rough surface texture. These nanowires are mass produced in alumina membranes. The second strategy produces long and rough Au nanowires on lithographically patternable nickel edge templates with corrugations formed by partial etching. These rough nanowires can be easily arrayed and integrated with microscale devices. KeywordsRoughness-Nanowire-Alumina template-Lithographic template-Synthesis methodsJournal of Nanoparticle Research 03/2010; 12(3):1065-1072. DOI:10.1007/s11051-010-9875-8 · 2.18 Impact Factor