Dip-pen Nanolithography Technique Research Articles

Evolution from dip-pen nanolithography to mechanochemical printing

<sec>As a unique nanomanipulation and nanofabrication tool, dip-pen nanolithography (DPN) has enjoyed great success in the past two decades. The DPN can be used to create molecular patterns with nanoscale precision on a variety of substrates with different chemistry properties. Since its advent, the DPN has been steadily improved in the sense of applicable inks, fabrication throughput, and new printing chemistry. Among these developments, mechanical force induced mechanochemistry is of special interest.</sec><sec>In this review, we introduce the physical principles behind the DPN technique. We highlight the development of DPN for writing with various types of “inks”, including small molecules, viscous polymer solutions, lipids, and biomolecules, especially, the development of thermal-DPN allowing printing with inks that are usually in solid phase at room temperature. Next, we introduce the parallel-DPN and polymer pen nanolithography. These techniques greatly speed up the fabrication speed without sacrificing the precision. We also summarize the advances in chemical reaction based DPN technologies, including electrochemical DPN, metal tip-induced catalytical DPN, and mechanochemical DPN (or mechanochemical printing). To further elaborate the mechanism behind the mechanochemical printing, we briefly review the development of mechanochemistry, including the reaction mechanism, various experimental approaches to realizing mechanochemistry, and recent development in this field. We highlight the advantages of using atomic force microscopy to study mechanochemistry at a single molecule level and indicate the potential of combining this technique with DPN to realize mechanochemical printing. We envision that with the further discovery of novel mechanophores that are suitable for mechanochemical printing, this technique can be broadly applied to nanotechnology and atomic fabrication.</sec>

Richards Award to Chad Mirkin

Chad A. Mirkin, the George B. Rathmann Professor of Chemistry and director of the International Institute for Nanotechnology at Northwestern University, is the winner of the 2018 Theodore William Richards Medal Award in recognition of his “conspicuous achievements in chemistry.” The award is presented by the American Chemical Society Northeastern Section. Mirkin is known for his discovery and development of spherical nucleic acids, which have applications including extracellular and intracellular molecular diagnostics, gene regulation, and immune modulation. He also pioneered the dip-pen nanolithography technique, which uses atomic force microscope tips to deposit nanoscale materials onto a substrate.

Direct-Patterning SWCNTs Using Dip Pen Nanolithography for SWCNT/Silicon Solar Cells.

Dip pen nanolithography (DPN) is used to pattern single-walled carbon nanotube (SWCNT) lines between the n-type Si and SWCNT film in SWCNT/Si solar cells. The SWCNT ink composition, loading, and DPN pretreatment are optimized to improve patterning. This improved DPN technique is then used to successfully pattern >1 mm long SWCNT lines consistently. This is a 20-fold increase in the previously reported direct-patterning of SWCNT lines using the DPN technique, and demonstrates the scalability of the technique to pattern larger areas. The degree of the uniformity of SWCNTs in these lines is further characterized by Raman spectroscopy and scanning electron microscopy. The patterned SWCNT lines are used as thin conductive pathways in SWCNT/Si solar cells, similar to front contact electrodes. The critical parameters of these solar cells are measured and compared to control cells without SWCNT lines. The addition of SWCNT lines increases power conversion efficiency by 40% (relative). Importantly, the SWCNT lines reduce average series resistance by 44%, and consequently increase average fill factor by 24%.

Size effect on polarization switching kinetics of P(VDF-TrFE) copolymer nanodots

We demonstrate polarization switching kinetics of poly(vinylidene fluoride-ran-trifluoroethylene) P(VDF-TrFE) nanodots depending on their sizes. Ferroelectric copolymer P(VDF-TrFE) nanodots, ranging from 20 to 250 nm in lateral size, were deposited on a Nb-doped SrTiO3 substrate by a position-controlled dip-pen nanolithography technique. Ferroelectric switching characteristics of P(VDF-TrFE) nanodots was investigated by piezoresponse force microscopy. Asymmetric switching behavior was observed during switching process, indicating that the threshold electric fields for polarization reversal were measured differently under the same conditions according to the switching polarity. Significantly, when the size of P(VDF-TrFE) nanodot approached around 250 nm, electric fields for polarization switching were compatible with those of the P(VDF-TrFE) thin film. We suggest that the electric fields required for polarization reversal of the P(VDF-TrFE) nanodots present asymmetric switching behaviors, and asymptotic behavior be observed as the nanodots increase in lateral size.

Mask-less deposition of Au–SnO2 nanocomposites on CMOS MEMS platform for ethanol detection

Here we report on the mask-less deposition of Au–SnO2 nanocomposites with a silicon-on-insulator (SOI) complementary metal oxide semiconductor (CMOS) micro electro mechanical system (MEMS) platform through the use of dip pen nanolithography (DPN) to create a low-cost ethanol sensor. MEMS technology is used in order to achieve low power consumption, by the employment of a membrane structure formed using deep reactive ion etching technique. The device consists of an embedded tungsten micro-heater with gold interdigitated electrodes on top of the SOI membrane. The tungsten micro-heater is used to raise the membrane temperature up to its operating temperature and the electrodes are used to measure the resistance of the nanocomposite sensing layer. The CMOS MEMS devices have high electro-thermal efficiency, with 8.2 °C temperature increase per mW power of consumption. The sensing material (Au–SnO2 nanocomposite) was synthesised starting from SnO nanoplates, then Au nanoparticles were attached chemically to the surface of SnO nanoplates, finally the mixture was heated at 700 °C in an oven in air for 4 h. This composite material was sonicated for 2 h in terpineol to make a viscous homogeneous slurry and then ‘written’ directly across the electrode area using the DPN technique without any mask. The devices were characterised by exposure to ethanol vapour in humid air in the concentration range of 100–1000 ppm. The sensitivity varied from 1.2 to 0.27 ppm−1 for 100–1000 ppm of ethanol at 10% relative humid air. Selectivity measurements showed that the sensors were selective towards ethanol when they were exposed to acetone and toluene.

Adsorption mechanisms of L-Glutathione on Au and controlled nano-patterning through Dip Pen Nanolithography.

Dip Pen Nanolithography technique has been employed for patterning L-Glutathione tripeptide (l-y-glutamyl-l-cysteinyl-glycine) nanostructures at specific locations on metallic Au(111) substrate. The formed supramolecular architectures were designed through straight lines and dots serving as precursors for building blocks assemblies in nano-bio-electronics applications or as template structures for functionalized particles in the form of host-guest networks. Tween 20 polyoxyethylene surfactant concentrations ranging from 0.005 to 0.1% (v/v) into initial l-Glutathione tripeptide (2 mg mL(-1)) ink solutions were sequentially tested for the improvement of the ink delivery process and to assure an optimum uniformity and homogeneity over the patterned space. A strong relationship was found between the coated atomic force microscope (AFM) cantilever within the highly effective Tween 20 activator adjuvant and the molecular diffusion along concentration gradients. An increase in the driving force for ink transport from the AFM tip has been demonstrated within the highest 0.1% (v/v) TW 20 surfactant concentration, favoring the patterning of GSH molecules routinely with sub-100 nm resolution. Self-assembled monolayers of GSH were also fabricated and characterized in the light of X-ray photoemission spectroscopy (XPS) and ellipsometric optical measurements. Adsorption from water of l-Glutathione to the gold substrate is proven to be made by the thiol group of cysteine. Theoretical DFT approaches were applied for quantum chemical studies dedicated to electronic processes underneath molecular GSH/Au(111) systems.

Four-States Multiferroic Memory Embodied Using Mn-Doped BaTiO3 Nanorods

Multiferroics that show simultaneous ferroic responses have received a great deal of attention by virtue of their potential for enabling new device paradigms. Here, we demonstrate a high-density four-states multiferroic memory using vertically aligned Mn-doped BaTiO3 nanorods prepared by applying the dip-pen nanolithography technique. In the present nanorods array, the polarization (P) switching by an external electric field does not influence the magnetization (M) of the nanorod owing to a negligible degree of the P-M cross-coupling. Similarly, the magnetic-field-induced M switching is unaffected by the ferroelectric polarization. On the basis of these, we are able to implement a four-states nonvolatile multiferroic memory, namely, (+P,+M), (+P,-M) ,(-P,+M), and (-P,-M) with the reliability in the P and M switching. Thus, the present work makes an important step toward the practical realization of multistate ferroic memories.

Adsorption of bovine serum albumin on amorphous carbon surfaces studied with dip pen nanolithography

This article reports the use of dip pen nanolithography (DPN) for the study of adsorption of bovine serum albumin (BSA) proteins on amorphous carbon surfaces; tetrahedral amorphous carbon (t-aC) and silicon doped hydrogenated amorphous carbon (a-C:H:Si). Contact angle study shows that the BSA proteins reduce the contact angle on both carbon materials. We also noticed that the drop volume dependence is consistent with a negative line tension, i.e. due to an attractive protein/surface interaction. The DPN technique was used to write short-spaced (100 nm) BSA line patterns on both samples. We found a line merging effect, stronger in the case of the a-C:H:Si material. We discuss possible contributions from tip blunting, scratching, cross-talk between lever torsion and bending and nano-shaving of the patterns. We conclude that the observed effect is caused in large measure by the diffusion of BSA proteins on the amorphous carbon surfaces. This interpretation of the result is consistent with the contact angle data and AFM force curve analysis indicating larger tip/surface adhesion and spreading for the a-C:H:Si material. We conclude by discussing the advantages and limitations of DPN lithography to study biomolecular adsorption in nanoscale wetting environments.

Nanoscale resistive random access memory consisting of a NiO nanodot and Au nanowires formed by dip-pen nanolithography

We demonstrate the nanoscale resistive random access memory (RRAM) element consisting of an approximately 30nm diameter NiO nanodot and two bridging Au nanowires, formed by a dip-pen nanolithography technique using nickel carbonate (Ni2(CO3)(OH)2) and [AuCl4]− complex solutions, respectively. The Au/NiO/Au nanowire resistive switch exhibits typical unipolar switching characteristics with high performance at low Set and Reset voltages.

Fabricating protein immunoassay arrays on nitrocellulose using Dip-pen lithography techniques

Advancements in lithography methods for printing biomolecules on surfaces are proving to be potentially beneficial for disease screening and biological research. Dip-pen nanolithography (DPN) is a versatile micro and nanofabrication technique that has the ability to produce functional biomolecule arrays. The greatest advantage, with respect to the printing mechanism, is that DPN adheres to the sensitive mild conditions required for biomolecules such as proteins. We have developed an optimised, high-throughput printing technique for fabricating protein arrays using DPN. This study highlights the fabrication of a prostate specific antigen (PSA) immunoassay detectable by fluorescence. Spot sizes are typically no larger than 8 μm in diameter and limits of detection for PSA are comparable with a commercially available ELISA kit. Furthermore, atomic force microscopy (AFM) analysis of the array surface gives great insight into how the nitrocellulose substrate functions to retain protein integrity. This is the first report of protein arrays being printed on nitrocellulose using the DPN technique and the smallest feature size yet to be achieved on this type of surface. This method offers a significant advance in the ability to produce dense protein arrays on nitrocellulose which are suitable for disease screening using standard fluorescence detection.

Serial and Parallel Dip-Pen Nanolithography Using a Colloidal Probe Tip

AFM tips terminated with PMMA colloids are used to pattern molecules in both serial and parallel modes by allowing the polymer on the tip to swell under different humidity conditions. This extension of the dip-pen nanolithography technique provides an easy methodology to place inks on different substrates without the need to perform specialized tip alignment.

Nanopatterning of catalyst by Dip Pen nanolithography (DPN) for synthesis of carbon nanotubes (CNT)

Carbon nanotubes (CNT) were synthesized on nanopatterned catalysts. The catalyst nanoparticles were obtained using dip pen nanolithographytechnique. Dip pen nanolithography technique was used to deposit NiCl(2) nanopatterns with sub-200 nm feature sizes on a silicon substrate. The deposited features were verified by using lateral force microscopy. The substrate was then placed in a plasma-enhanced chemical vapor deposition instrument to synthesize CNT. The synthesized CNT were characterized using scanning electron microscopy and energy dispersive x-ray spectroscopy.

Temperature-Dependent Formation of Dendrimer Islands from Ring Structures

Previously unobserved high surface mobility and phase transformation phenomena in condensed, micron-scale dendrimer structures are documented using atomic force microscopy. Stratified dendrimer rings (a unique morphology resulting from microdroplet evaporation of dendrimer-alcohol solutions on mica) undergo dramatic temperature, time, and dendrimer-generation-dependent morphological changes associated with large-scale molecular rearrangements and partial melting. These transformations produce ring structures consisting of a highly stable first monolayer of the scalloped structure in equilibrium with spherical cap shaped dendrimer islands that form at the center of each pre-existing scallop (creating a "pearl necklace" structure). A generation-dependent critical temperature for dendrimer melting is determined. As-evaporated structures can be stabilized against thermally driven rearrangements by holding them at room temperature before annealing. Analysis of the dendrimer island shapes reveals a dependence of island contact angle on contact line curvature (island size) that varies systematically with dendrimer generation. A negative line tension, tau, is deduced in these systems. The morphological transformations in this system indicate the potential for creating complex, dendrimer-based multilevel structures and macroscopic-scale arrays using, for example, droplet-on-demand or dip pen nanolithography techniques, coupled with appropriate annealing and stabilizing treatments.

Fabrication of CdSe/ZnS Quantum-Dot-Conjugated Protein Microarrays and Nanoarrays

We demonstrate the fabrication and the detection of protein microarrays and nanoarrays, which are tagged by using colloidal CdSe/ZnS quantum dots (QDs), for the purpose of optical readout of those biochips. A microarrayer and a dip-pen nanolithography technique were used for the fabrication of QD-labeled protein microarrays and nanoarrays, respectively. The optical readout of those biochips was conducted by using a microchip scanner and a confocal scanning microscope in the case of the microarrays while an atomic force microscope was employed for characterizing the nanoarrays. We also report a possible way of reducing the ‘doughnut phenomenon’ in microarrays by varying the spot size from 300 μm to 100 μm, wherein the fluorescence intensity distribution becomes more uniform with decreasing spot diameter.

Fabrication of F0F1-ATPase Nanostructure on Gold Surface Through Dip-Pen Nanolithography

DPN (Dip-Pen nanolithography) is one kind of widely used technique to create nanoscopic patterns of many different materials. FoF1-ATPase is nano scale rotary molecular motor, and it would be an ideal motor or energy providing device in micro/nano system. In this paper, we used DPN technique to create nanoarrays of F0F1-ATPase within chromatophore on gold surface. The feature size of our F0F1-ATPase patterns was 270 nm in average, and there were no more than 20 F0F1-ATPases in each dot. The activity of patterned F0F1-ATPase was demonstrated by its ATP synthesis, which was indicated by the fluorescence change of labeled F1300. The patterned F0F1-ATPase nanoarrays can be further used as biosensor, or power providing system. And precisely patterning F0F1-ATPase with desired size, position and biological activity will accelerate its application in many basic and application research fields.

Preparation of $\hbox{F}_{0}\hbox{F}_{1}$ -ATPase Nanoarray by Dip-Pen Nanolithography and Its Application as Biosensors

Dip-pen nanolithography (DPN) is a widely used technique to create nanoscopic patterns of many different materials. F(0)F(1) -ATPase is a nanoscale rotary molecular motor, and could be used as a biosensor or an ideal motor device in a micro-/nanosystem. In this paper, the DPN technique was used to create nanoarrays of F(0)F(1) -ATPase within chromatophore on a gold surface. The feature size of our F(0)F(1) -ATPase patterns was an average of 130 nm, and mathematically, there were no more than ten F(0)F(1) -ATPases in each dot. The biological activity of patterned F(0)F(1) -ATPase was demonstrated by its adenosine triphosphate synthesis, which was indicated by the fluorescence change of labeled F1300. The patterned F(0)F(1) -ATPase nanoarrays were further constructed as biosensors to detect H9 influenza A virus. The results showed that the biosensor arrays had a remarkable S/N ratio and excellent specificity. This type of biosensor arrays can be further used in high-throughput, high-sensitive detection in future. Meanwhile, the precise patterning of F(0)F(1) -ATPase with desired size, position, and biological activity would accelerate its application in many fields.

Dip Pen Nanolithography Functionalized Electrical Gaps for Multiplexed DNA Detection

Nanoparticle-based, silver-enhanced DNA electrical detection shows great promise for point-of-care diagnostics. In this paper, we demonstrate that the dip pen nanolithography (DPN) method can be used to precisely functionalize multiple electrical gaps for multiplexed DNA detection. With the use of the DPN technique, capture ssDNAs are written inside 5 microm x 10 microm electrical gaps on substrates. The DPN functionalized electrical gaps can specifically hybridize to target ssDNAs in solution. Successful hybridization of the capture-target DNA complex is detected by the use of gold nanoparticles carrying ssDNA, which also hybridize to the target ssDNA, followed by silver enhancement. The drop of resistance across the gaps due to the formation of metal nanoparticle-DNA complexes is measured over time and compared against characteristics of control gaps, which are either left unfunctionalized or functionalized with noncomplementary capture ssDNA. This technique has potential for high-density multiplexed DNA assay chips. Multiplex detection of two different target ssDNAs in solution using DPN functionalized electrical gaps on the same chip is demonstrated. The lowest detection limit is 10 pM.

Controlled Growth of Long GaN Nanowires from Catalyst Patterns Fabricated by “Dip-Pen” Nanolithographic Techniques

Long gallium nitride (GaN) nanowires were directly grown on SiO2 substrates from spatially defined locations using a chemical vapor deposition method. Locations of the GaN nanowires were well-controlled by using atomic force microscope (AFM)-based “dip-pen” nanolithography (DPN) and other patterning methods to precisely pattern catalyst islands on the substrate. Devices made of single GaN nanowires were fabricated and characterized. The convenient use of patterning techniques, especially the DPN technique, demonstrates a practical route to control the location of nanowires and for in situ fabrication of nanowire devices.

Au “Ink” for AFM “Dip-Pen” Nanolithography

Scanning probe lithography is a rapidly growing research field, in which atomic force microscope based “dip-pen” nanolithography (DPN) is a simple new technique for creating chemically distinct nanostructures on surfaces in a “direct-write” fashion. Previous works demonstrate the transport of alkanethiols to a gold substrate, resulting in the formation of patterned self-assembled monolayers. Here, we show that surface-induced reduction of metal ions combined with DPN can be used to create metallic nanostructures on Si surfaces. Au nanostructures with sub-100-nm resolution can be created routinely, showing that the DPN technique is a general method for nanofabrication.

Tiny pen plotter makes big mark at nanoscale

Using teeny letters to convey a great big message, researchers at Northwestern University, Evanston, III., have printed a microscopic-sized excerpt from late physicist Richard Feynman's 40-year-old futuristic speech on the subject of miniaturization. Postdoctoral associate Seunghun Hong, graduate student Jin Zhu, and chemistry professor Chad A. Mirkin can draw letters and other patterns with nanometer-scale spatial control in a fast and automated fashion using a new multiple-ink version of their dip-pen nanolithography technique [ Science , 286, 523 (1999)]. The method may lead to advances in fabricating nanocircuits and preparing new catalysts and chemical sensors. In this demonstration, the group uses an atomic force microscope tip as a pen nib to write the paragraph with a single molecular layer of mercaptohexadecanoic acid ink on a gold surface. The neatly aligned characters show high contrast against the background because each letter is surrounded by a single molecular layer of octadecanethiol—a s...