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Nanoporous Gold: Fabrication, Characterization, and Applications  [PDF]
Erkin Seker,Michael L. Reed,Matthew R. Begley
Materials , 2009, DOI: 10.3390/ma2042188
Abstract: Nanoporous gold (np-Au) has intriguing material properties that offer potential benefits for many applications due to its high specific surface area, well-characterized thiol-gold surface chemistry, high electrical conductivity, and reduced stiffness. The research on np-Au has taken place on various fronts, including advanced microfabrication and characterization techniques to probe unusual nanoscale properties and applications spanning from fuel cells to electrochemical sensors. Here, we provide a review of the recent advances in np-Au research, with special emphasis on microfabrication and characterization techniques. We conclude the paper with a brief outline of challenges to overcome in the study of nanoporous metals.
Conducting Polymer 3D Microelectrodes  [PDF]
Luigi Sasso,Patricia Vazquez ?,Indumathi Vedarethinam,Jaime Castillo-León,Jenny Emnéus,Winnie E. Svendsen
Sensors , 2010, DOI: 10.3390/s101210986
Abstract: Conducting polymer 3D microelectrodes have been fabricated for possible future neurological applications. A combination of micro-fabrication techniques and chemical polymerization methods has been used to create pillar electrodes in polyaniline and polypyrrole. The thin polymer films obtained showed uniformity and good adhesion to both horizontal and vertical surfaces. Electrodes in combination with metal/conducting polymer materials have been characterized by cyclic voltammetry and the presence of the conducting polymer film has shown to increase the electrochemical activity when compared with electrodes coated with only metal. An electrochemical characterization of gold/polypyrrole electrodes showed exceptional electrochemical behavior and activity. PC12 cells were finally cultured on the investigated materials as a preliminary biocompatibility assessment. These results show that the described electrodes are possibly suitable for future in-vitro neurological measurements.
Fabrication and characterization of large arrays of mesoscopic gold rings on large-aspect-ratio cantilevers  [PDF]
D. Q. Ngo,I. Petkovic,A. Lollo,M. A. Castellanos-Beltran,J. G. E. Harris
Physics , 2014, DOI: 10.1063/1.4896980
Abstract: We have fabricated large arrays of mesoscopic metal rings on ultrasensitive cantilevers. The arrays are defined by electron beam lithography and contain up to $10^5$ rings. The rings have a circumference of 1 $\mu$m, and are made of ultrapure (6N) Au that is deposited onto a silicon-on-insulator wafer without an adhesion layer. Subsequent processing of the SOI wafer results in each array being supported at the end of a free-standing cantilever. To accommodate the large arrays while maintaining a low spring constant, the cantilevers are nearly 1 mm in both lateral dimensions and 100 nm thick. The extreme aspect ratio of the cantilevers, the large array size, and the absence of a sticking layer are intended to enable measurements of the rings' average persistent current $\langle I \rangle$ in the presence of relatively small magnetic fields. We describe the motivation for these measurements, the fabrication of the devices, and the characterization of the cantilevers' mechanical properties. We also discuss the devices' expected performance in measurements of $\langle I \rangle$.
Fabrication and Characterization of 3D Micro- and Nanoelectrodes for Neuron Recordings  [PDF]
Maria Dimaki,Patricia Vazquez,Mark Holm Olsen,Luigi Sasso,Romen Rodriguez-Trujillo,Indumathi Vedarethinam,Winnie E. Svendsen
Sensors , 2010, DOI: 10.3390/s101110339
Abstract: In this paper we discuss the fabrication and characterization of three dimensional (3D) micro- and nanoelectrodes with the goal of using them for extra- and intracellular studies. Two different types of electrodes will be described: high aspect ratio microelectrodes for studying the communication between cells and ultimately for brain slice recordings and small nanoelectrodes for highly localized measurements and ultimately for intracellular studies. Electrical and electrochemical characterization of these electrodes as well as the results of PC12 cell differentiation on chip will be presented and discussed.
Electrical Characterization of a Thiol SAM on Gold as a First Step for the Fabrication of Immunosensors based on a Quartz Crystal Microbalance  [PDF]
Asma Tlili,Adnane Abdelghani,Salwa Hleli,Mhamed A. Maaref
Sensors , 2004, DOI: 10.3390/s40670105
Abstract: In order to develop a robust biosensor based on quartz crystal microbalance technique for antigen detection, a control of the steps of the surface functionalization has been performed by impedance spectroscopy. The gold electrode is functionalized with the self-assembled monolayer technique. The high insulating properties of the acidic thiol monolayer has been characterized with cyclic voltammetry and impedance spectroscopy. The modified surface is activated with N-hydroxysuccinimide(NHS) and 1-(3-(dimethylamino)propyl)-3-ethylcarbodimide hydrochloride(EDC) cross-linker for antibody coupling. The non-specific sites are blocked with bovin serum albumine molecules. Different concentrations of antigen can be detected with a good reversibility in real time with the quartz crystal microbalance.
Electrochemical Fabrication and Electrocatalytic Properties of Nanostructured Mesoporous Platinum Microelectrodes
Mengyan NIE,Joanne MElliott,
Mengyan NIE
,Joanne M.Elliott

材料科学技术学报 , 2005,
Abstract: Electrodeposition from a lyotropic liquid crystal template medium was used to produce nanostructured platinum microelectrodes with high specific surface area and high mass transport efficiency. Compared to polished and conventional platinized microelectrodes, well-ordered nanostructured platinum microelectrodes exhibited enhanced electrocatalytic properties for oxygen and ascorbic acid, whilst well-ordered nanostructured platinum microelectrodes offered improved electrocatalytic properties for oxygen reduction compared to disordered nanostructured platinum microelectrodes.
FABRICATION AND CHARACTERIZATION OF GOLD NANOPARTICLES LOADED MICROCAPSULES
纳米金掺杂中空微胶囊的制备与表征

FENG Zhiqiang,GAO Changyou,SHEN Jiacong,
封志强
,高长有,沈家骢

高分子学报 , 2008,
Abstract: A convenient method was developed to fabricate gold nanoparticles loaded microcapsules in one step and with high efficiency.First of all,the gold colloidal solution was prepared through reduction of AuCl~-_4 ions with NaBH_4 under stirring,and poly(vinylpyrrolidone)(PVP) was added quickly under severe agitation to prevent the aggregation of the gold nanoparticles during the dialyses.The gold nanoparticles in the colloidal solution had a diameter of about 7 nm and had a maximum absorption at 516 nm.Next,template polymerization of acrylic acid(AA) in the presence of PVP and 3-(trimethoxysilyl) propyl methacrylate(MPS) modified silica particles was carried out in the gold colloidal solution.The polymerization was initiated by K_2S_2O_8 and maintained for about 2 h under nitrogen atmosphere.After polymerization,the resulting composite particles were separated from the dispersion through centrifugation and were washed with triply-distilled water for several times.Finally,the gold nanoparticle-loaded microcapsules were obtained after core-removal with HF.In this process,the pre-adsorption of the complex of PVP/AA onto the gold nanoparticles made the nanoparticles polymerizable with free AA monomers during the template polymerization,and the gold nanoparticles doped PAA/PVP complex films were formed on the surfaces of the silica particles.After the core-removal process,the hollow nature and the integrity of the obtained microcapsules in both dry and wet states were demonstrated by scanning electron microscopy and confocal laser scanning microscopy,respectively.The entrapment of the gold nanoparticles in the capsules was confirmed by transmission electron microscopy.Electron diffraction pattern of the nanoparticles-loaded microcapsules showed the gold polycrystalline diffraction rings,from which the lattice constant of crystal plane {1 1 1} was calculated as 0.4174 nm,further confirming the existence of the gold nanoparticles.The gold nanoparticles were distributed uniformly in the microcapsule shells with no sign of aggregations.The amount of nanoparticles loaded in the microcapsule shells could be tuned by the concentration of the gold colloidal solution,(i.e.)higher concentration resulted in microcapsules with larger amount of gold nanoparticles in the shells.This process can be extended to other types of nanoparticles and polymers,thus can be widely applied to obtain composite microcapsules with desired functions.
Flexible Polyimide Microelectrodes Array for Transcorneal Electrical Stimulation  [PDF]
Luis Ni?o de-Rivera, Fidel W. Pérez-Tovar, Jorge Santiago Amaya, Félix Gil Carrasco
Journal of Biomedical Science and Engineering (JBiSE) , 2015, DOI: 10.4236/jbise.2015.88051
Abstract: The relationship between the parameters of Transcorneal Electrical Stimulation (TES) and its neuro-protective effect of TES on axotomised Retinal Ganglion Cells (RGCs) is still unclear. This work discusses the design strategy of a new non conventional TES stimulator, the micro fabrication processes and characterization of an array of MEMS microelectrodes over a flexible polymer layer substrate to stimulate the human cornea. The micro-array of electrodes, over a flexible smooth biocompatible polyimide substrate, fine tunes the curvature of the cornea. This tool can help researchers to define the optimal electric stimulation parameters required in TES.
PEDOT–CNT Composite Microelectrodes for Recording and Electrostimulation Applications: Fabrication, Morphology, and Electrical Properties  [PDF]
Ramona Gerwig,Alfred Stett,Martin Stelzle
Frontiers in Neuroengineering , 2012, DOI: 10.3389/fneng.2012.00008
Abstract: Composites of carbon nanotubes and poly(3,4-ethylenedioxythiophene, PEDOT) and layers of PEDOT are deposited onto microelectrodes by electropolymerization of ethylenedioxythiophene in the presence of a suspension of carbon nanotubes and polystyrene sulfonate. Analysis by FIB and SEM demonstrates that CNT–PEDOT composites exhibit a porous morphology whereas PEDOT layers are more compact. Accordingly, capacitance and charge injection capacity of the composite material exceed those of pure PEDOT layers. In vitro cell culture experiments reveal excellent biocompatibility and adhesion of both PEDOT and PEDOT–CNT electrodes. Signals recorded from heart muscle cells demonstrate the high S/N ratio achievable with these electrodes. Long-term pulsing experiments confirm stability of charge injection capacity. In conclusion, a robust fabrication procedure for composite PEDOT–CNT electrodes is demonstrated and results show that these electrodes are well suited for stimulation and recording in cardiac and neurophysiological research.
Toward on-chip, in-cell recordings from cultured cardiomyocytes by arrays of gold mushroom-shaped microelectrodes  [PDF]
Anna Fendyur,Micha E. Spira
Frontiers in Neuroengineering , 2012, DOI: 10.3389/fneng.2012.00021
Abstract: Cardiological research greatly rely on the use of cultured primary cardiomyocytes (CMs). The prime methodology to assess CM network electrophysiology is based on the use of extracellular recordings by substrate-integrated planar Micro-Electrode Arrays (MEAs). Whereas this methodology permits simultaneous, long-term monitoring of the CM electrical activity, it limits the information to extracellular field potentials (FPs). The alternative method of intracellular action potentials (APs) recordings by sharp- or patch-microelectrodes is limited to a single cell at a time. Here, we began to merge the advantages of planar MEA and intracellular microelectrodes. To that end we cultured rat CM on micrometer size protruding gold mushroom-shaped microelectrode (gMμEs) arrays. Cultured CMs engulf the gMμE permitting FPs recordings from individual cells. Local electroporation of a CM converts the extracellular recording configuration to attenuated intracellular APs with shape and duration similar to those recorded intracellularly. The procedure enables to simultaneously record APs from an unlimited number of CMs. The electroporated membrane spontaneously recovers. This allows for repeated recordings from the same CM a number of times (>8) for over 10 days. The further development of CM-gMμE configuration opens up new venues for basic and applied biomedical research.
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