Graphene Micropatterns Research Articles

Highly Selective Ammonia Detection in NiO‐Functionalized Graphene Micropatterns for Beef Quality Monitoring

Highly Selective Ammonia Detection in NiO‐Functionalized Graphene Micropatterns for Beef Quality Monitoring

Development of Light-Scribing Process Using L-Ascorbic Acid for Graphene Micro-Supercapacitor.

The rapid development of smart technologies is accelerating the growing demand for microscale energy storage devices. This work reports a facile and practical approach to fabricating interdigitated graphene micro-patterns through the LSC process accompanied by the l-ascorbic acid (L-AA) and preheating treatment. Our work offered a higher degree of GO reduction than the conventional microfabrication. It significantly shortened the overall processing time to obtain the micro-patterns with improved electrical and electrochemical performances. The interdigitated MSC composed of 16 electrodes exhibited a high capacitance of 14.1 F/cm3, energy density of 1.78 mWh/cm3, and power density of 69.9 mW/cm3. Furthermore, the fabricated MSC device demonstrated excellent cycling stability of 88.2% after 10,000 GCD cycles and a high rate capability of 81.1% at a current density of 1.00 A/cm3. The fabrication process provides an effective means for producing high-performance MSCs for miniaturized electronic devices.

In situ growth of laser-induced graphene micro-patterns on arbitrary substrates.

In this article we report a new laser processing method, combining the in situ graphitization of polyimide with simultaneous transfer of the graphene patterns to arbitrary substrates. The synthesis conditions are similar to those normally used for the well-known laser-induced graphene method. The approach is based on the enclosure of polyimide sheets between microscope glass slides. Graphene patterns have been successfully generated on glass and on PDMS, as well as graphene decorated with metals and oxides. In order to illustrate the usefulness of the proposed approach, the method was applied to the fabrication of hybrid supercapacitors, which exhibited very good electrochemical performance.

Laser-Induced fluorinated graphene for superhydrophobic surfaces with anisotropic wetting and switchable adhesion

We present a facile direct-write approach for patterning fluorine-doped nanocarbons directly on molecularly engineered polymers for superhydrophobic and parahydrophobic surfaces. We first synthesized two different polymer films, non-fluorinated and fluorinated polyimides (PIs), by two-step procedure to create poly(amic acid) precursors, followed by thermal curing. Morphology and chemical composition were controlled by adjusting the programmed scan line pitch from 101.6 to 508 μm during lasing to achieve superhydrophobicity with a water contact angle (CA) up to 156° in the direction perpendicular to carbonized lines. Droplets exhibited strong adhesion on our porous graphene micropatterns even when held at vertical and inverted orientations, indicating a Cassie impregnating state of wetting. Parahydrophobic F-LINC with line pitch of 355.6 μm exhibits high dynamic CAs along both perpendicular (θA⊥ = 165°, θR⊥ = 127°) and parallel directions (θA‖ = 147°, θR‖ = 87°) as well as highly anisotropic CA hysteresis (Δθ⊥ = 38°, Δθ‖ = 60°). Moreover, we demonstrate strain-induced switchable adhesion by leveraging substrate curvature control. Further, we show that our micropatterned polymer films can be used for transferring droplets without any loss or contamination. Hence, our approach offers new insights into designing interfaces for droplet manipulation, pick-and-place applications, and localized control of reactions.

Direct Polymer Curing: Tailored Graphene Micropatterns by Wafer‐Scale Direct Transfer for Flexible Chemical Sensor Platform (Adv. Mater. 2/2021)

Direct Polymer Curing: Tailored Graphene Micropatterns by Wafer‐Scale Direct Transfer for Flexible Chemical Sensor Platform (Adv. Mater. 2/2021)

Tailored Graphene Micropatterns by Wafer-Scale Direct Transfer for Flexible Chemical Sensor Platform.

2D materials, such as graphene, exhibit great potential as functional materials for numerous novel applications due to their excellent properties. The grafting of conventional micropatterning techniques on new types of electronic devices is required to fully utilize the unique nature of graphene. However, the conventional lithography and polymer-supported transfer methods often induce the contamination and damage of the graphene surface due to polymer residues and harsh wet-transfer conditions. Herein, a novel strategy to obtain micropatterned graphene on polymer substrates using a direct curing process is demonstrated. Employing this method, entirely flexible, transparent, well-defined self-activated graphene sensor arrays, capable of gas discrimination without external heating, are fabricated on 4 in. wafer-scale substrates. Finite element method simulations show the potential of this patterning technique to maximize the performance of the sensor devices when the active channels of the 2D material are suspended and nanoscaled. This study contributes considerably to the development of flexible functional electronic devices based on 2D materials.

Evaluating Single Layer Graphene Micropatterns Induced by Ti:Sa Laser Irradiation

Due to the unique optical and electrical properties of graphene and its potential application in microelectronics and spintronics, precise micropatterning graphene on substrates has found significant attention for optimal performance of many these applications. This study investigates the process of patterning single layer graphene on a SiO2/Si substrate using Ti:Sa laser irradiation. A variety of laser fluences are employed for the removal of graphene from the substrate surface as the film is scanned at different speeds and required laser fluences for the removal of graphene are determined at these speeds. This is performed because pulse overlapping is an effective parameter for successful removal of graphene from substrates, which results in different ablation thresholds for each laser scanning speed. Changes of produced channels widths are also investigated as a function of total laser fluences. Study of Raman spectra of patterned graphene film is performed by Raman microspectroscopy to evaluate the quality of laser produced micropatterns. It includes the investigations of intensity changes of defect D and D′ bands on graphene edge. Optical contrasts are also calculated for both graphene and graphene edge and the results are compared.

Highly Tunable and Scalable Fabrication of 3D Flexible Graphene Micropatterns for Directing Cell Alignment.

Patterning graphene allows to precisely tune its properties to manufacture flexible functional materials or miniaturized devices for electronic and biomedical applications. However, conventional lithographic techniques are cumbersome for scalable production of time- and cost-effective graphene patterns, thus greatly impeding their practical applications. Here, we present a simple scalable fabrication of wafer-scale three-dimensional (3D) graphene micropatterns by direct laser tuning graphene oxide reduction and expansion using a LightScribe DVD writer. This one-step laser-scribing process can produce custom-made 3D graphene patterns on the surface of a disk with dimensions ranging from microscale up to decimeter scale in about 20 min. Through control over laser-scribing parameters, the resulting various 3D graphene patterns are exploited as scaffolds for controlling cell alignment. The 3D graphene patterns demonstrate their potential to biomedical applications, beyond the fields of electronics and photonics, which will allow to incorporate flexible graphene patterns for 3D cell or tissue culture to promote tissue engineering and drug testing applications.

An Ultrasensitive, Selective, Multiplexed Superbioelectronic Nose That Mimics the Human Sense of Smell.

Human sensory-mimicking systems, such as electronic brains, tongues, skin, and ears, have been promoted for use in improving social welfare. However, no significant achievements have been made in mimicking the human nose due to the complexity of olfactory sensory neurons. Combinational coding of human olfactory receptors (hORs) is essential for odorant discrimination in mixtures, and the development of hOR-combined multiplexed systems has progressed slowly. Here, we report the first demonstration of an artificial multiplexed superbioelectronic nose (MSB-nose) that mimics the human olfactory sensory system, leading to high-performance odorant discriminatory ability in mixtures. Specifically, portable MSB-noses were constructed using highly uniform graphene micropatterns (GMs) that were conjugated with two different hORs, which were employed as transducers in a liquid-ion gated field-effect transistor (FET). Field-induced signals from the MSB-nose were monitored and provided high sensitivity and selectivity toward target odorants (minimum detectable level: 0.1 fM). More importantly, the potential of the MSB-nose as a tool to encode hOR combinations was demonstrated using principal component analysis.

Mask-free and programmable patterning of graphene by ultrafast laser direct writing

Reported here is a mask-free and programmable patterning of graphene by using femtosecond laser direct writing on graphene oxide (GO) films. Take advantage of the ultrahigh instantaneous intensity of the femtosecond laser pulse, and especially its nonlinear interactions with materials, the GO could be efficiently reduced under atmospheric condition at room temperature. Moreover, the designability of femtosecond laser direct writing (FsLDW) technique allow making graphene micropatterns arbitrarily according to the preprogrammed structures, which provides the feasibility for rational design, flexible fabrication and integration of graphene-based micro-devices. Raman spectra show that the reduced and patterned region is very homogeneous, which is confirmed by the almost consistent ID/IG ratio. The novel graphene patterning technique would provide a technical support for the development of graphene-based micro-devices for future electronics.

Fabrication of Stable Ultrathin Transparent Conductive Graphene Micropatterns Using Layer by Layer Self-Assembly

Fabrication of Stable Ultrathin Transparent Conductive Graphene Micropatterns Using Layer by Layer Self-Assembly

Site-specific stamping of graphene micro-patterns over large areas using flexible stamps

Site-specific stamping has the potential of becoming a low-cost, high-throughput method for depositing specific-shaped graphene micro-patterns over large areas on a wide variety of substrates. The use of an approach involving flexible stamps presented here represents an important advance towards reaching that potential. This approach entails lithographic creation (dry etching) of high-quality micro-pillar arrays of highly oriented pyrolytic graphite (HOPG) over large areas. This is followed by embedding the micro-pillar arrays in polydimethylsiloxane (PDMS), and detaching them from the HOPG base. This results in flexible stamps containing embedded HOPG micro-pillar arrays with freshly cleaved stamping surfaces. The flexible HOPG/PDMS stamps are then brought into contact with substrate surfaces to site-specifically stamp graphene or few-layer graphene (FLG) arrays over large areas. The freshly cleaved nature of the micro-pillar surfaces in the flexible stamps, the low elastic modulus of the flexible stamps and the elimination of sidewall deposits on the micro-pillars allow for more uniform stamping, relative to the use of stiff HOPG stamps from earlier studies. This approach has the potential to expand the substrate choice for graphene or FLG stamping to include curved and/or flexible substrates that could have an impact on the burgeoning field of flexible/stretchable electronics.

Large-Scale Graphene Micropatterns via Self-Assembly-Mediated Process for Flexible Device Application

We report on a method for the large-scale production of graphene micropatterns by a self-assembly mediated process. The evaporation-induced self-assembly technique was engineered to produce highly ordered graphene patterns on flexible substrates in a simplified and scalable manner. The crossed stripe graphene patterns have been produced over a large area with regions consisting of single- and two-layer graphene. Based on these graphene patterns, flexible graphene-based field effect transistors have been fabricated with an ion-gel gate dielectric, which operates at low voltages of < 2 V with a hole and electron mobility of 214 and 106 cm(2)/V·s, respectively. The self-assembly approach described here may pave the way for the nonlithographic production of graphene patterns, which is scalable to large areas and compatible with roll-to-roll system.

Multifunctional Polydiacetylene-Graphene Nanohybrids for Biosensor Application

Graphene nanosheet hybridized with polydiacetylene (PDA) can be used as the electrochemical biosensor applications. Self-assembly and photo-polymerization chemistry of diacetylenic monomers on reduced graphene oxide (RGO) for non-covalent functionalization were used for high solubility and further functionality of graphene in water necessary for biosensor application. This enables regular graphene micropatterns to be formed on large substrates with chemical bonding and biological interactions. The PDA/RGO nanohybrids demonstrated the formation of conjugated polymer on graphene for fluorescence and electrochemical detection. The optical and structural properties of PDA/RGO, characterized by UV-Vis, FT-IR, Raman, and photoluminescence spectrometers, demonstrated that PDA and RGO in PDA/RGO are connected by physical interactions. Further-functionalization action of PDA/RGO with biotin was verified in microfluidic biochip via biotin-straptavidin interaction. Here, the applicability of functionalized RGO in the biochip and biosensing platform based on fluorescence detection was confirmed. The electrochemical experiments showed the potential of functionalized RGO for use as an electrochemical biosensor, especially with the detection of an analyte at low concentration.