Dip-pen Nanolithography Research Articles

Non-Centrosymmetric Single Crystalline Biomolecular Nano-Arrays for Responsive Electronics.

Herein, a novel strategy is reported for synthesizing libraries of single crystalline amino acid (AA) nanocrystals with control over size, anisotropy, and polymorphism by leveraging dip-pen nanolithography (DPN) and recrystallization via solvent vapor annealing. The crystals are prepared by first depositing nanoreactors consisting of a solvent with AAs, followed by water vapor-induced recrystallization. This leads to isotropic structures that are non-centrosymmetric with strong piezoelectric (g33 coefficients >1000mVmN-1), ferroelectric, and non-linear optical properties. However, recrystallizing arrays of isotropic DL-alanine nanodot features with a binary solvent (water and ethanol) leads to arrays of 1D piezoelectric nanorods with their long axis coincident with the polar axis. Moreover, positioning nanoreactors containing AAs (the nanodot features) between micro electrodes leads to capillary formation, making the reactors anisotropic and facilitating piezoelectric nanorod formation between the electrodes. This offers a facile route to device fabrication. These as-fabricated devices respond to ultrasonic stimulation in the form of a piezoelectric response. The technique described herein is significant as it provides a rapid way of investigating non-centrosymmetric nanoscale biocrystals, potentially pivotal for fabricating a new class of stimuli-responsive devices such as sensors, energy harvesters, and stimulators.

High‐Precision Materials Printer for Fast Prototyping of Electronic Devices Based on 2D Materials

AbstractThere is an increasing interest in printed electronics driven principally by flexible and wearable applications. The interest stems from the ability to fabricate electronic devices, such as Field Effect Transistors (FET), more efficiently in terms of materials use and cost‐effectively than traditional lithographic techniques. Challenges persist in achieving high resolution and accuracy in defining device geometry. In the study, a high‐resolution materials printer able to achieve resolutions in the micron range, surpassing the capabilities of commercially available printers is successfully designed and fabricated. The printer incorporates an all‐in‐one printing system, comprising Inkjet and a Dip Pen Nanolithography (DPN) technique, enabling both additive and subtractive manufacturing at the microscale. The experiments demonstrate the successful fabrication of FETs based on 2D materials (2DMs), with micrometric channel lengths exhibiting a high degree of controllability and repeatability, even when contacting limited channel regions as micrometer‐sized molybdenum disulfide (MoS2) flakes. Electrical characterizations of the fabricated devices underscore the significant technological advancements achieved by the prototypes.

Asymmetric [Dy2] molecules deposited into micro-SQUID susceptometers: in situ characterization of their magnetic integrity.

The controlled integration of magnetic molecules into superconducting circuits is key to developing hybrid quantum devices. Herein, we study [Dy2] molecular dimers deposited into micro-SQUID susceptometers. The results of magnetic, heat capacity and magnetic resonance experiments, backed by theoretical calculations, show that each [Dy2] dimer fulfills the main requisites to encode a two-spin quantum processor. Arrays of between 2 × 108 and 7 × 109[Dy2] molecules were optimally integrated under ambient conditions inside the 20 μm wide loops of micro-SQUID sensors by means of dip-pen nanolithography. Equilibrium magnetic susceptibility and phonon-assisted spin tunneling dynamics measured in situ substantiate that these molecules preserve spin ground states, magnetic interactions and magnetic asymmetry that characterize them in bulk. These results show that it is possible to interface multi-qubit molecular complexes with on-chip superconducting circuits without disturbing their relevant properties and suggest the potential of soft nanolithography techniques to achieve this goal.

Prediction of Nanoscale Water Meniscus Shape between Deliquescent KDP Crystal Optics and AFM Probe for Water-Dissolution Repairing.

KDP (KH2PO4) crystal optics are the key elements for megajoule laser facilities. Nanoscale surface defects would cause laser-induced damage when the optics are irradiated by a high-fluence laser (over 10 J/cm2). Dip-pen nanolithography (DPN) could be used to repair the nanoscale surface defects in the KDP optics by the water meniscus. The high humidity required for high-efficiency and soft KDP surfaces penetrated by the AFM probe brings challenges for accurately predicting the water meniscus shape to evaluate the effectiveness of the DPN water-dissolution repairing. The multisolutions of the Young-Laplace and Kelvin equations also lead to the wrong water meniscus shape. A theoretical model that takes the high humidity and the penetration of the AFM probes into account is developed. The parametrization Young-Laplace equations are adopted for the zero contact angle of the water films, and the AFM probe is treated as the combination of the cone and sphere for the water meniscus whose size is larger than the AFM tip radius under high humidity. The penetration of the AFM probe is modeled by Hertz theory. Both the water films (3.3 nm thickness at 99% relative humidity) and indentations (1.46 nm depth at 300 nN contact force) are non-negligible for the nanoscale water meniscus between the KDP surface and the AFM probe. Moreover, the rough-fine two-step method is proposed to lock the correct solution of the Young-Laplace and Kelvin equations. The effectiveness of the proposed model is verified by comparison with reported ESEM images and pull-off forces. In addition, the overgrowth dots on the KDP surface are compared with the water meniscus. The linear growth of the water meniscus would cause the linear growth of the overgrowth dot, which proves the proposed model could be used to guide the DPN water-dissolution repairing for the nanoscale surface defects in the KDP optics.

Enhanced HER Efficiency of Monolayer MoS2 via S Vacancies and Nano-Cones Array Induced Strain Engineering.

Molybdenum disulfide (MoS2) has gained significant attention as a promising catalyst for hydrogen evolution reaction (HER). The catalytic performance of MoS2 can be enhanced by either altering its structure or regulating external conditions. In this study, a novel approach combining the introduction of sulfur vacancy (VS) and biaxial tensile strain to create more active sites and modulate the band structure of monolayer MoS2 is proposed. To achieve the desired strain level, nano-cones (NCs) array substrates facilely fabricated by dip-pen nanolithography (DPN) are employed. The magnitude of the applied tensile strain can be finely tuned via adjusting the height of the NCs. Furthermore, on-chip electrochemical devices are constructed based on artificial structures, enabling precise optimization of HER performance of MoS2 through the synergistic effect of VS and strain. Combined with the d-band theory, it reveals that the HER properties of VS-MoS2 are highly dependent on the degree of tensile strain. This study presents a promising avenue for the design and preparation of high-performance 2D catalysts for energy conversion and storage applications.

Development of Meta-Chemical Surface by Dip-Pen Nanolithography for Precise Electrochemical Lead Sensing.

Dip-pen nanolithography (DPN) is a powerful and unique technique for precisely depositing tiny nano-spherical cap shapes (nanoclusters) onto a desired surface. In this study, a meta-chemical surface (MCS; a pattern with advanced features) is developed by DPN and applied to electrochemical lead sensing, yielding a calibration curve in the ppb range. An ink mixture of PMMA and NTPH (which binds to Pb (II), as supported by DFT calculations) is patterned over a Pt surface. The average height of the nanoclusters is ≈13nm with a high surface area-to-volume ratio, which depends on the ink composition and the MCS surface. This ratio affected the sensitivity of the MCS as a detecting tool. The results indicate that the sensor's features can be controlled by the ability to control the size of the nanoclusters, attributed to the unique properties of the DPN production method. These results are significant for the water-source purification industry.

Glucose Oxidase Patterned Meta‐Chemical Surface for Sensing Glucose Using Dip‐Pen Nanolithography

AbstractNumerous studies have been done to advance the development of efficient, simple, and cheap sensors, especially for glucose, which are important in the pharmaceutical and food industries. The most common sensors and biosensors used today are based on electrochemistry. The novelty of this study is the use of dip‐pen nanolithography (DPN) in order to pattern a mixture of glucose oxidase with PMMA as nanoclusters and develop meta‐chemical surface (MCS), which leads to highly efficient working electrodes with increased detection sensitivity compared to the today‐known glucose sensors ( M was detected in the current study). Our novel and important results support the feasibility of using DPN to develop sensors on various electrode surfaces patterned with different active species, especially in systems requiring target substance detection over large concentration ranges.

Effect of heat treatment on resistive switching memory characteristics of NiO nanodots of tens of nanometers shattered by AFM tips

The characteristics of resistive random access memory (RRAM) at the nanometer scale are increasingly important for RRAM cells with further miniaturization. We report the RRAM characteristics of NiO nanodots in the order of tens of nanometers. NiO nanodots of approximately 70 nm were created on a single-crystal Nb-doped SrTiO3 (Nb:STO) substrate by dip-pen nanolithography. For comparison, a NiO thin film was also deposited on the Nb:STO substrate by spin coating. To reduce the size of NiO nanodots, they were shattered by an atomic force microscope tip, obtaining nanodots of approximately 10 nm. Using a conductive atomic force microscope, we characterized the current according to the applied electric field of the NiO nanodots on the Nb:STO substrate with a capacitor configured of Pt/NiO/Nb:STO substrate. When compared with the NiO thin film, the forming voltage of the NiO nanodots decreased. In addition, the shattered NiO nanodots exhibited unipolar switching characteristics, and the forming and set/reset voltages decreased with the reduction in nanodot size. Furthermore, the NiO nanodots exhibited a substantially reduced forming and set/reset voltages after heat treatment in vacuum. We suggest that the oxygen-depleted layer formed on the surface of NiO nanodots by heat treatment plays a crucial role in the reduction of the forming and operation voltages.

Quantitative nanopatterning of fg-scale liquids with dip-pen nanolithography

The ability to precisely pattern nanoscale amounts of liquids is essential for biotechnology and high-throughput chemistry, but controlling fluid flow on these scales is very challenging. Scanning probe lithography methods such as dip-pen nanolithography (DPN) provide a mechanism to write fluids at the nanoscale, but this is an open loop process as methods to provide feedback while patterning sub-pg features have yet to be reported. Here, we demonstrate a novel method for programmably nanopatterning liquid features at the fg-scale through a combination of ultrafast atomic force microscopy probes, the use of spherical tips, and inertial mass sensing. We begin by investigating the required probe properties that would provide sufficient mass responsivity to detect fg-scale mass changes and find ultrafast probes to be capable of this resolution. Further, we attach a spherical bead to the tip of an ultrafast probe as we hypothesize that the spherical tip could hold a drop at its apex which both facilitates interpretation of inertial sensing and maintains a consistent fluid environment for reliable patterning. We experimentally find that sphere-tipped ultrafast probes are capable of reliably patterning hundreds of features in a single experiment. Analyzing the changes in the vibrational resonance frequency during the patterning process, we find that drift in the resonance frequency complicates analysis, but that it can be removed through a systematic correction. Subsequently, we quantitatively study patterning using sphere-tipped ultrafast probes as a function of retraction speed and dwell time to find that the mass of fluid transferred can be modulated by greater than an order of magnitude and that liquid features as small as 6 fg can be patterned and resolved. Taken together, this work addresses a persistent concern in DPN by enabling quantitative feedback for nanopatterning of aL-scale features and lays the foundation for programmably nanopatterning fluids.

Patterning of Hydrophilic and Hydrophobic Gold and Magnetite Nanoparticles by Dip Pen Nanolithography (Small 18/2023)

Dip Pen Nanolithography In article number 2208069, Bart Jan Ravoo and co-workers report the surface patterning of nanoparticles using dip pen nanolithography. Metal and metal oxide nanoparticles functionalized with various organic ligands can be patterned in nanosized clusters. Depending on the polarity of the ligand shell, water or toluene is used as ink solvent. No modification of atomic force microscope (AFM) tip or substrate surface is required.

Aluminum Hydroxide Nano- and Microstructures Fabricated Using Scanning Probe Lithography with KOH Ink.

Using scanning probe lithography (SPL) with KOH ink, this study fabricates aluminum hydroxide (Al(OH)3) nano- and microfeatures on a gold (Au) film that has been deposited on an aluminum (Al) layer. Hydroxyl ions (OH-) from the KOH ink loaded onto the Au film can react with the underlying Al layer to form Al(OH)3 structures due to the decrease in the pH of the reacting solution.1 In this process, Al(OH)3 solidification is governed by the pH of the KOH ink solution, which is affected by its volume. Suitably small volumes (down to hundreds of attoliters) of the KOH ink solution can be applied to the substrate surface using dip-pen nanolithography (DPN) and polymer-pen lithography (PPL). Using DPN and PPL printing with the solid (i.e., gel) and liquid phases of KOH ink, sub-micron- (minimum ≈300 nm) and micron-sized (≥4 μm) Al(OH)3 features can be obtained, respectively. The fabrication of Al(OH)3 structures using the proposed pH-dependent solidification process can be achieved with relatively small volumes in ambient conditions without requiring a previously reported molding process.1,2.

3D Nanolithography by Means of Lipid Ink Spreading Inhibition (Small 10/2023)

Lipid Ink Spreading Inhibition In article number 2205590, Eider Berganza, Michael Hirtz, and co-workers utilize dip-pen nanolithography to print lipid patches layer-by-layer forming 3D structures on a surface coated with serum albumin stabilizing the structures. The lipid molecules transfer from the probe to the substrate through a water meniscus. To further improve their stability, lipid-structures get covered with a few nanometers of gold through physical vapor deposition.

Patterning of Hydrophilic and Hydrophobic Gold and Magnetite Nanoparticles by Dip Pen Nanolithography.

Nanoparticles offer unique physical and chemical properties. Dip pen nanolithography of nanoparticles enables versatile patterning and nanofabrication with potential application in electronics and sensing, but is not well studied yet. Herein, the patterned deposition of various nanoparticles onto unmodified silicon substrates is presented. It is shown that aqueous solutions of hydrophilic citrate and cyclodextrin functionalized gold nanoparticles as well as poly(acrylic) acid decorated magnetite nanoparticles are feasible for writing nanostructures. Both smaller and larger nanoparticles can be patterned. Hydrophobic oleylamine or n-dodecylamine capped gold nanoparticles and oleic acid decorated magnetite nanoparticles are deposited from toluene. Tip loading is carried out by dip-coating, and writing succeeds fast within 0.1s. Also, coating with longer tip dwell times, at different relative humidity and varying frequency are studied for deposition of nanoparticle clusters. The resulting feature size is between 300 and 1780nm as determined by scanning electron microscopy. Atomic force microscopy confirms that the heights of the deposited structures correspond to a single or double layer of nanoparticles. Higher writing speeds lead to smaller line thicknesses, offering possibilities to more complex structures. Dip pen nanolithography can hence be used to pattern nanoparticles on silicon substrates independent of the surface chemistry.

Dilute Gd hydroxycarbonate particles for localized spin qubit integration.

Molecular spins are considered as the quantum hardware to build hybrid quantum processors in which coupling to superconducting devices would provide the means to implement the necessary coherent manipulations. As an alternative to large magnetically-dilute crystals or concentrated nano-scale deposits of paramagnetic molecules that have been studied so far, the use of pre-formed sub-micronic spherical particles of a doped Gd@Y hydroxycarbonate is evaluated here. Particles with an adjustable number of spin carriers are prepared through the control of both particle size and doping. Bulk magnetic properties and continuous wave and time-domain-EPR spectroscopy show that the Gd spins in these particles are potential qubits with robust quantum coherence. Monolayers of densely-packed particles are then formed interfacially and transferred successfully to the surface of Nb superconducting resonators. Alternatively, these particles are disposed at controlled localizations as isolated groups of a few particles through Dip-Pen Nanolithography using colloidal organic dispersions as ink. Altogether, this study offers new material and methodologies relevant to the development of viable hybrid quantum processors.

3D Nanolithography by Means of Lipid Ink Spreading Inhibition.

While patterning 2D metallic nanostructures are well established through different techniques, 3D printing still constitutes a major bottleneck on the way to device miniaturization. In this work a fluid phase phospholipid ink is used as a building block for structuring with dip-pen nanolithography. Following a bioinspired approach that relies on ink-spreading inhibition, two processes are presented to build 2D and 3D metallic structures. Serum albumin, a widely used protein with an innate capability to bind to lipids, is the key in both processes. Covering the sample surface with it prior to lipid writing, anchors lipids on the substrate, which ultimately allows the creation of highly stable 3D lipid-based scaffolds to build metallic structures.

Ferroelectric domain wall current corresponding to ferroelectric domain structures of BaTiO3 nanodots fabricated by dip-pen nanolithography

In this study, we investigated the ferroelectric domain wall current corresponding to the ferroelectric domain structures of BaTiO3 (BTO) nanodots deposited on Nb-doped SrTiO3 substrates using the dip-pen nanolithography (DPN) method. By controlling the DPN deposition time, the deposited BTO nanodots with a diameter of 60–200 nm were crystallized by heat treatment at 800°C. The ferroelectric domain structures of BTO nanodots were observed through piezoresponse force microscope studies, and the formation of domain walls was observed. Relatively large ferroelectric domain wall currents formed on the ferroelectric domain wall produced by BTO nanodots and currents corresponding to the ferroelectric polarization direction around the domain wall were observed through a conducting atomic force microscope.

Grafted polythiophene pendent polymer brushes and their electronanopatterning

• Nanolithography and patterning using polymer brushes with terthiophene pendents. • Terthiophene-containing chain transfer agent macroinitiator. • Nanolithography and patterning were done using conducting atomic force microscopy. • Nanopattern properties depend on the applied bias voltage and scan rate. Electrochemical nanolithography using grafted polymer brushes with terthiophene (3T) pendent was investigated. The film was fabricated by surface electropolymerization of a reversible addition−fragmentation chain-transfer agent macroinitiator containing a 3T pendant molecule and the subsequent polymer brush growth from a 3T functionalized methacrylate monomer (3T-Methacrylate). Electrochemical nanolithography and patterning were done using conducting atomic force microscopy (C-AFM) enabling precise nanopattern fabrication. In contrast to direct nanowriting, dip pen nanolithography, and nanolithographic additive manufacturing, the electrochemical nanolithography can be readily facilitated by applying a bias voltage between a conductive AFM tip and the grafted polymer brush film at ambient conditions and without ink transfer. The height and electrical resistance of the nanopatterns were dependent on the writing parameters (i.e. applied bias voltage and scan rate).

Design Strategies for Structurally Controlled Polymer Surfaces via Cyclophane-Based CVD Polymerization and Post-CVD Fabrication.

Molecular structuring of soft matter with precise arrangements over multiple hierarchical levels, especially on polymer surfaces, and enabling their post-synthetic modulation has tremendous potential for application in molecular engineering and interfacial science. Here, recent research and developments in design strategies for structurally controlled polymer surfaces via cyclophane-based chemical vapor deposition (CVD) polymerization with precise control over chemical functionalities and post-CVD fabrication via orthogonal surface functionalization that facilitates the formation of designable biointerfaces are summarized. Particular discussion about innovative approaches for the templated synthesis of shape-controlled CVD polymers, ranging from 1D to 3D architecture, including inside confined nanochannels, nanofibers/nanowires synthesis into an anisotropic media such as liquid crystals, and CVD polymer nanohelices via hierarchical chirality transfer across multiple length scales is provided. Aiming at multifunctional polymer surfaces via CVD copolymerization of multiple precursors, the structural and functional design of the fundamental [2.2]paracyclophane (PCP) precursor molecules, that is, functional CVD monomer chemistry is also described. Technologically advanced and innovative surface deposition techniques toward topological micro- and nanostructuring, including microcontact printing, photopatterning, photomask, and lithographic techniques such as dip-pen nanolithography, showcasing research from the authors' laboratories as well as other's relevant important findings in this evolving field are highlighted that have introduced new programmable CVD polymerization capabilities. Perspectives, current limitations, and future considerations are provided.

Electron donor or acceptor behavior of a AuCl3 dopant manipulated by dip-pen nanolithography on a MoS2 thin-film transistor

Gold (III) chloride (AuCl3) is a well-known electron acceptor (p-type dopant). Here, the electron donor or acceptor behavior of a AuCl3 dopant on a molybdenum disulfide (MoS2) thin-film transistor (TFT) is demonstrated by line patterning a concentration-adjusted AuCl3 ink with dip-pen nanolithography (DPN). At a low ink concentration (clow) (<3 mM AuCl3), the Au molecules (Au0) are transferred and contact with the MoS2, resulting in an electron donor effect on the MoS2. In contrast, at a high ink concentration (chigh) (≥3 mM), the Au3+ is transferred from the AuCl3 salt loaded on the DPN tip probe and reacts with the MoS2, resulting in an electron acceptor effect. For a clow, the mobility of the MoS2 TFT increases when the Au coverage is larger than 10%. For a chigh, the mobility decreases regardless of the Au coverage. This DPN patterning of the concentration-adjusted AuCl3 inks can be applied to fabricate junction in the local area of MoS2 devices without using complicated lithography. As a result, enhancement of the photoresponse as well as increasing the rectifying behavior of MoS2 devices are demonstrated with the bandgap controlled junction obtained by two direct DPN line patterning operations with the concentration-adjusted AuCl3 inks.

Large area multivalent protein nanopatterns for cell mimic studies

Systematic study of cellular interactions in a 2D tissue culture requires specific control of a set of ligands relevant for the particular interaction. Many cellular- and signaling interactions happen at the nanoscale, and a nanopatterning toolkit can shed more light on these interactions. Multi-ligand nanopatterning approaches, such as dip-pen nanolithography and DNA origami nanoarrays, are currently available for multivalency studies in biological systems. However, dip-pen nanolithography is slow and requires specialized instruments, while the DNA origami-based approaches are restricted in dimensions, highly negatively charged and unstable in physiological conditions.