电化学"沾笔"纳米刻蚀及其他（英文）

本文提出了一种基于"沾笔"纳米刻蚀和电化学还原技术在表面上制备金属及半导体纳米结构的普适性方法.用这种方法可以在硅表面直接书写线宽度低于50纳米的多种金属和半导体组成的纳米结构.这种简单而有效的方法在精确控制位置和结构的功能化纳米器件制备中具有重要的潜在应用前景.     

Site-directed exchange studies with combinatorial libraries of nanostructures

We describe a new combinatorial method for studying the exchange between solution adsorbates and nanoscale features within libraries generated via dip-pen nanolithography. Four different compounds, 1-octadecanethiol, 16-mercaptohexadecanoic acid, ferrocene (11-mercaptoundecyl), and ferrocene (11-mercapto-1-oxoundecyl), are studied on amorphous and single-crystal gold substrates. This series of adsorbates allows us to compare the exchange properties of patterns of nanoscale features as a function of composition, feature size, and type of underlying substrate. Moreover, these properties can be compared and contrasted with bulk SAM properties. The novel strategy provides not only a method for initiating site-specific exchange processes but also a way of extracting kinetic information about the rate of such processes in situ.     

Single-layer graphene oxide sheet: a novel substrate for dip-pen nanolithography

Graphene oxide (GO) sheet is used as a novel substrate for dip-pen nanolithography (DPN). After GO is transferred onto SiO(2) using the Langmuir-Blodgett technique, CoCl(2) is patterned on both GO and exposed SiO(2) substrates simultaneously by DPN, which is used for growth of different structured carbon nanotubes.     

Transport rates vary with deposition time in dip-pen nanolithography

By patterning with dip-pen nanolithography using tip dwell times ranging from 15 s to 2 h over a period of 19 h, we show that the transport rate for smaller patterns is different than for larger ones. This transport behavior is found for both 1-octadecanethiol (ODT) and 16-mercaptohexadecanoic acid (MHDA) inks on gold substrates. Additionally, MHDA shows an overall decrease in transport rate as a function of total writing time during such experiments. These results indicate that measurements with short dwell times are insufficient to determine transport rates for larger features.     

Multiplexed arrays of chemosensors by parallel dip-pen nanolithography

Miniaturized combined arrays of three different pH indicators allowing for sensitive, robust and broad-range acidity detection are prepared by parallel dip-pen nanolithography, which proves the potential of this technique to fabricate multiplexed platforms at the micro- and nanoscale that can act as sensors.     

Protein nanostructures formed via direct-write dip-pen nanolithography

We report a tip modification strategy coupled with dip-pen nanolithography for depositing proteins on a surface. This methodology offers patterning capabilities on the scale of 45 nm to many micrometers length. The biorecognition properties of nanofeatures composed of immunoglobulin-gamma (IgG) were confirmed by reacting the array with gold nanoparticles coated with anti-IgG. Furthermore, a two component nanoarray was fabricated in direct-write fashion by DPN, and the biorecognition properties of this structure were investigated by AFM without biodiagnostic labels.     

Dip-pen patterning and surface assembly of peptide amphiphiles

This paper presents results on controlling the surface morphology of evaporation-driven self-assembly of peptide amphiphile (PA) nanofibers by dip-pen nanolithography. These PA nanofibers, which measure only a few nanometers in diameter, can be oriented perpendicularly to the receding edge of a solution. Dragging a meniscus of PA ink with an atomic force microscope (AFM) tip creates reproducibly aligned arrays of isolated and close-packed PA nanofiber patterns on silicon substrates, utilizing surface coating of poly(ethylene glycol) to suppress the self-assembly of nanofibers on AFM tips. We also demonstrate the ability to construct double-layer patterns of differing nanofiber orientations at the same position. This result could be important in producing a complex, multilayer pattern of these peptide-based supramolecular nanostructures.     

Site-specific fabrication of nanoscale heterostructures: local chemical modification of GaN nanowires using electrochemical dip-pen nanolithography

This article describes a new method for site-specific, atomic force microscope (AFM) fabrication of nanowire heterostructures using electrochemical dip-pen nanolithography (E-DPN). We have demonstrated that E-DPN is ideally suited for the in situ modification of nanoscale electronic devices; the AFM tip and the nanowire device can be used as electrodes and the reactants for the modification can be introduced by coating them onto the AFM tip. Specifically, we have created GaN nanowire heterostructures by a local electrochemical reaction between the nanowire and a tip-applied KOH "ink" to produce gallium nitride/gallium oxide heterostructures. By controlling the ambient humidity, reaction voltage, and reaction time, good control over the modification geometry is obtained. Furthermore, after selective chemical etching of gallium oxide, unique diameter-modulated nanowire structures can be produced. Finally, we have demonstrated the unique device fabrication capabilities of this technique by performing in situ modification of GaN nanowire devices and characterizing the device electronic transport properties. These results demonstrate that small modifications of nanowire devices can lead to large changes in the nanowire electron transport properties.     

Spontaneous "phase separation" of patterned binary alkanethiol mixtures

This article describes novel phase-separation behavior by a binary mixture of alkanethiols when deposited onto a gold surface using micro- and nanodeposition tools, such as microcontact printing (muCP) and dip-pen nanolithography (DPN). This behavior is significantly different than that observed in the bulk. We demonstrate this behavior using three model compounds: 16-mercaptohexadecanoic acid (MHA), 1-octadecanethiol (ODT), and CF3(CF2)11(CH2)2SH (PFT). The identity of the resulting segregated structure is confirmed by lateral force microscopy (LFM) and by selective metal-organic coordination chemistry. Importantly, this phenomenon can be exploited to print sub-100 nm wide alkanethiol lines via conventional muCP and to form sub-15 nm features using DPN, which is below the ultimate resolution of both these techniques. We also demonstrate that these nano-patterned materials can serve as templates for constructing more complex architectures.     

Dip-pen刻蚀技术直接构建聚-L-赖氨酸纳米结构

Dip-pen纳米刻蚀技术(简称DPN技术)为在目标基底上沉积一个有序或连续的图案提供了一条简单而有效的途径,DPN技术是一种直接书写的扫描探针刻蚀技术,它使用原子力显微镜探针针尖,在一定的驱动力下,直接将化学试剂“墨水”转移到目标基底上．近年来,利用DPN技术已经成功地实现了多种“墨水一基底”组合。     

Direct electrochemical nanopatterning of polycarbazole monomer and precursor polymer films: ambient formation of thermally stable conducting nanopatterns

The direct nanopatterning of polycarbazole on ultrathin films of a "precursor polymer" and monomer under ambient conditions is reported. In contrast to previous reports on electrochemical dip-pen nanolithography using monomer ink or electrolyte-saturated films in electrostatic nanolithography, these features were directly patterned on spin-cast films of carbazole monomer and poly(vinylcarbazole) (PVK) under room temperature and humidity conditions. Using a voltage-biased atomic force microscope (AFM) tip, electric-field-induced polymerization and cross-linking occurred with nanopatterning in these films. Different parameters, including writing speed and bias voltages, were studied to demonstrate line width and patterning geometry control. The conducting property (current-voltage (I-V) curves) of these nanopatterns was also investigated using a conducting-AFM (C-AFM) setup, and the thermal stability of the patterns was evaluated by annealing the polymer/monomer film above the glass transition (T(g)) temperature of the precursor polymer. To the best of our knowledge, this is the first report in which thermally stable conducting nanopatterns were drawn directly on monomer or polymer film substrates using an electrochemical nanolithography technique under ambient conditions.     

Patterning of cantilevers with inverted dip-pen nanolithography: efforts toward combinatorial AFM

We report patterning of AFM cantilevers by inverted dip-pen nanolithography, thereby markedly enhancing the development of combinatorial AFM as a high-throughput force-measuring instrument capable of determining interactions between opposing libraries of biomolecules.     

Dynamic meniscus growth at a scanning probe tip in contact with a gold substrate

Environmental scanning electron microscopy was used to investigate the dynamic meniscus growth at a cantilever in contact with a substrate. The meniscus was observed to take many minutes to reach an equilibrium state. The observed growth rate is similar to initial patterning rates observed from dip-pen nanolithography and suggest that the meniscus growth may be the rate-limiting step in initial pattering rates.     

Enzymatic nanolithography of a self-assembled oligonucleotide monolayer on gold

This paper describes a simple strategy to biochemically manipulate a surface at the nanoscale by enzyme dip-pen nanolithography using an endonuclease (DNase I) that is directly patterned on a self-assembled monolayer presenting a terminal oligonucleotide. Physisorbed nanopatterns of DNase I carried out nanoscale enzymology at the surface creating oligonucleotide patterns with the fidelity of the patterned enzyme because of the affinity of the enzyme for the immobilized, oligonucleotide substrate.     

A resistless photolithography method for robust markers and electrodes

We describe a method of resistless photolithography using laser for the fabrication of microscopic markers and electrodes. A single shot of laser (355 nm, 100 mJ) is used to induce local surface melting and thus transfer a pattern from the mask (TEM grid) on to the surface of silicon. With a silicon substrate pre-coated with a layer of phosphorus, the laser pulse selectively produces doped regions that are highly conducting. The electrodes and markers thus obtained are robust and can withstand harsh chemical treatments. The utility of the marker for dip-pen nanolithography is illustrated by performing gold colloid nanopatterning.     

Evidence of meniscus interface transport in dip-pen nanolithography: An annular diffusion model

Ring shaped dots were patterned with mercaptohexadecanoic acid ink by dip-pen nanolithography. These dots have an ink-free inner core surrounded by an inked annular region, making them different from the filled dots usually obtained. This suggests a different transport mechanism than the current hypothesis of bulk water meniscus transport. A meniscus interface ink transport model is proposed, and its general applicability is demonstrated by predicting the patterned dot radii of chemically diverse inks.     

Creation of cadmium sulfide nanostructures using AFM dip-pen nanolithography

A dip-pen nanolithography (DPN) process capable of depositing nanoscaled structures of semiconducting CdS materials was developed by careful control of the reaction speed between the precursors. The new development expanded the scope of the powerful DPN process and provided more insight in the deposition mechanism. Features ranging from several hundreds of nanometers to sub-50 nanometers were generated and characterized. The effects of the surface property of the substrate, the relative humidity, the translating rate, and the temperature were systematically investigated. X-ray photoelectron spectroscopy (XPS) was used to verify the chemical composition of the patterns. In principle, this simple and convenient method should be applicable to deposit various metal sulfides on suitable substrates.     

Vapor phase polymerization of EDOT from submicrometer scale oxidant patterned by dip-pen nanolithography

Some of the most exciting recent advances in conducting polymer synthesis have centered around the method of vapor phase polymerization (VPP) of thin films. However, it is not known whether the VPP process can proceed using significantly reduced volumes of oxidant and therefore be implemented as part of nanolithography approach. Here, we present a strategy for submicrometer scale patterning of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) via in situ VPP. Attolitre (10(-18) L) volumes of oxidant "ink" are controllably deposited using dip-pen nanolithography (DPN). DPN patterning of the oxidant ink is facilitated by the incorporation of an amphiphilic block copolymer thickener, an additive that also assists with stabilization of the oxidant. When exposed to EDOT monomer in a VPP chamber, each deposited feature localizes the synthesis of conducting PEDOT structures of several micrometers down to 250 nm in width. PEDOT patterns are characterized by atomic force microscopy (AFM), conductive AFM, two probe electrical measurement, and micro-Raman spectroscopy, evidencing in situ vapor phase synthesis of conducting polymer at a scale (picogram) which is much smaller than that previously reported. Although the process of VPP on this scale was achieved, we highlight some of the challenges that need to be overcome to make this approach feasible in an applied setting.     

Double-ink dip-pen nanolithography studies elucidate molecular transport

We have investigated the transport mechanism of the inks most typically used in dip-pen nanolithography by patterning both 16-mercaptohexadecanoic acid (MHDA) and 1-octadecanethiol (ODT) on the same Au{111} substrate. Several pattern geometries were used to probe ink transport from the tip to the sample during patterning of both dots (stationary tip) and lines (moving tip). When ODT was written on top of a pre-existing MHDA structure, the ODT was observed at the outsides of the MHDA structure, and the transport rate increased. In the reverse case, the MHDA was also observed on the outsides of the previously patterned ODT features; however, the transport rate was reduced. Furthermore, the shapes of pre-existing patterns of one ink were not changed by deposition of the other ink. These results highlight the important role hydrophobicity plays, both of the substrate as well as of the inks, in determining transport properties and thereby patterns produced in dip-pen nanolithography.     

TAT peptide immobilization on gold surfaces: a comparison study with a thiolated peptide and alkylthiols using AFM, XPS, and FT-IRRAS

A TAT peptide was used to functionalize a gold surface by three different methods: adsorption from solution, microcontact printing, and dip-pen nanolithography (DPN). The composition and structure of the modified gold was characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Fourier transform -infrared reflection absorption spectroscopy (FT-IRRAS). We used two well-studied alkylthiols, mercaptohexadecanoic acid and 1-octadecanethiol, as a comparison in order to understand the structure of the TAT peptide monolayers prepared by the three methods. AFM studies allowed us to assess the homogeneity after each modification protocol. XPS was used to characterize the chemical composition of the gold surface after each functionalization procedure. The XPS results showed that surfaces modified with the TAT peptide by the three methods exhibit similar surface chemistry. Finally, FT-IRRAS experiments allowed us to conclude that the structure of the alkyl chains of the TAT peptides is fairly disordered and different after each procedure. Regardless of the type of surface functionalization method used, the monolayer of TAT peptide formed on the surface was of "liquidlike" nature.