Manufacturing Shape-Controllable Flexible PEDOT/rGO Composite Electrodes for Planar Micro-Supercapacitors

Flexible electronic products, with their characteristics of flexibility and wearability, have attracted significant attention and have become an important direction in the research and development of the electronics industry. Planar micro-supercapacitors (MSCs) with flexible composite electrodes can provide reliable energy support for these products, propelling their further development. The research employed a quick, effective, and environmentally friendly method of laser scribing to create shape-controllable flexible composite electrodes on composite films of Poly(3,4-ethylenedioxythiophene) and graphene oxide (PEDOT/GO), which were subsequently assembled into MSCs. An analysis of the composite electrode morphology, structure, and elemental distribution was conducted through the utilization of SEM, TEM, and XPS techniques. Following this, a comprehensive evaluation of the electrochemical performance of the flexible MSCs was carried out, which included cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and assessment of cyclic stability. The analysis of the CV results indicated that the MSCs achieved the areal capacitance of 5.78 mF/cm2 at 5 mV/s. After 5000 cycles at a current density of 0.05 mA/cm2, the capacitance retention rate was 85.4%. The high areal capacitance and strong cycle stability of MSCs highlight the potential of PEDOT/reduced graphene oxide (PEDOT/rGO) electrodes in electrode applications.

Efficient and Stable Perovskite Solar Modules Enabled by Inhibited Escape of Volatile Species

The intrinsically weak bonding structure in halide perovskite materials makes components in the thin films volatile, leading to the decomposition of halide perovskite materials. The reactions within the perovskite film are reversible provided that components do not escape the thin films. Here, a holistic approach is reported to improve the efficiency and stability of PSMs by preventing the effusion of volatile components. Specifically, a method for in situ generation of channel barrier layers for perovskite photovoltaic modules is developed. The resulting PSMs attain a certified aperture PCE of 21.37%, and possess remarkable continuous operation stability for maximum power point tracking (MPPT) of T90 > 1100 h in ambient air, and damp heat (DH) tracking of T93 > 1400 h.

Water-Responsive 3D Electronics for Smart Biological Interfaces

Three-dimensional (3D) electronic systems with their potential for enhanced functionalities often require complex fabrication processes. This paper presents a water-based, stimuli-responsive approach for creating self-assembled 3D electronic systems, particularly suited for biorelated applications. We utilize laser scribing to programmatically shape a water-responsive bilayer, resulting in smart 3D electronic substrates. Control over the deformation direction, actuation time, and surface curvature of rolling structures is achieved by adjusting laser-scribing parameters, as validated through experiments and numerical simulations. Additionally, self-locking structures maintain the integrity of the 3D systems. This methodology enables the implementation of spiral twining electrodes for electrophysiological signal monitoring in plants. Furthermore, the integration of self-rolling electrodes onto peripheral nerves in a rodent model allows for stimulation and recording of in vivo neural activities with excellent biocompatibility. These innovations provide viable paths to next-generation 3D biointegrated electronic systems for life science studies and medical applications.

Simultaneous Catechol and Hydroquinone Detection with Laser Fabricated MOF-Derived Cu-CuO@C Composite Electrochemical Sensor

The conversion of metal-organic frameworks (MOFs) into advanced functional materials offers a promising route for producing unique nanomaterials. MOF-derived systems have the potential to overcome the drawbacks of MOFs, such as low electrical conductivity and poor structural stability, which have hindered their real-world applications in certain cases. In this study, laser scribing was used for pyrolysis of a Cu-based MOF ([Cu4{1,4-C6H4(COO)2}3(4,4'-bipy)2]n) to synthesize a Cu-CuO@C composite on the surface of a screen-printed electrode (SPE). Scanning electron microscopy, X-ray diffractometry, and Energy-dispersive X-ray spectroscopy were used for the investigation of the morphology and composition of the fabricated electrodes. The electrochemical properties of Cu-CuO@C/SPE were studied by cyclic voltammetry and differential pulse voltammetry. The proposed flexible electrochemical Cu-CuO@C/SPE sensor for the simultaneous detection of hydroquinone and catechol exhibited good sensitivity, broad linear range (1-500 μM), and low limits of detection (0.39 μM for HQ and 0.056 μM for CT).

An Exploratory Study of Laser Scribing Quality through Cross-Section Scribing Profiles

This article presents a novel approach for evaluating laser scribing quality through cross-section profiles generated from a three-dimensional optical profiler. Existing methods for assessing scribing quality only consider the width and depth of a scribe profile. The proposed method uses a cubic spline model for cross-section profiles. Two quality characteristics are proposed to assess scribing accuracy and consistency. Accuracy is measured by the ratio of the actual laser-scribed area to the target area (RA), which reflects the deviation from the desired profile. The mean square error (MSE) is a measure of how close each scribed cross-section under the same scribing conditions is to the fitted cubic spline model. Over 1370 cross-section profiles were generated under 171 scribing conditions. Two response surface polynomial models for RA and MSE were built with 18 scribing conditions with acceptable scribing depth and RA values. Both RA and MSE were considered simultaneously via contour plots. A scatter plot of RA and MSE was then used for Pareto optimization. It was found that the cross-sectional profile of a laser scribe could be accurately represented by a cubic spline model. A multivariate nonlinear regression model for RA and MSE identified pulse energy and repetition rate as the two dominant laser parameters. A Pareto optimization analysis further established a Pareto front, where the best compromised solution could be found.

Laser Scribing for Electrode Patterning of Perovskite Spectrometer-Grade CsPbBr3 Gamma-ray Detectors

Making semiconductor radiation detectors that work at room temperature relies heavily on the deposition and pixelation of electrodes. Electrode patterning of perovskite solar cells widely implements laser scribing techniques, which is a convenient, scalable, and inexpensive technique. However, this method has not found its application in radiation detector patterning yet, and the question whether laser scribing can achieve high-quality patterns with minimum damage to a detector crystal and low interpixel cross-talk remains largely unanswered. To prove that laser scribing is a practical method for electrode patterning on perovskite CsPbBr₃ detectors, we use the material to create a variety of patterns. A very low lateral leakage current (60 nA at 10 V) and high mobility-lifetime product (9.7(3) × 10^-4 cm²/V) were observed between the pixel and the guard ring in tests of single-pixel devices with a separation of 200 or 100 μm between the central electrode and the guard ring. The 122 and 136 keV photopeaks in ⁵⁷Co gamma-ray spectra were very well resolved with an energy resolution of up to 6.1% at 122 keV. A further reduction in gap size to 50 μm is conceivable, but more process optimization is needed.

Wettability Controlled Surface for Energy Conversion

To achieve clean and high-efficiency utilization of renewable energy, functional surfaces with controllable and patternable wettability are becoming a fast-growing research focus. In this work, a laser scribing strategy to fabricate patterned graphene surfaces that are capable of energy conversion in different forms is demonstrated. Using the laser raster-scanning and vector-scanning modes, two distinct surface structures are constructed on polybenzoxazine substrate, yielding a superhydrophilic (LSHL) surface and superhydrophobic (LSHB) surface, respectively. Of particular note is that the unique hierarchical structure of LSHB surface has endowed it with quite a robust superwetting behaviors. Further profiting from the flexibility of the processing method, wettability patterns with spatially resolved LSHL and LSHB regions are designed, achieving the conversion of surface energy to liquid kinetic energy. This also offers a tractable approach to fabricate wettability-engineered devices that enable the directional, pumpless transport of water by capillary pressure gradient and the selective surface cooling via jet impingement. In addition, the LSHB surface demonstrates the high conversion of electric-to-thermal energy (222 °C cm² W^-1 ) and light-to-thermal energy (88%). Overall, the material system and processing method present a promising step forward to developing easy-fabricated graphene surfaces with spatially controlled wettability for efficient energy utilization and conversion.

Tuning the Structure, Conductivity, and Wettability of Laser-Induced Graphene for Multiplexed Open Microfluidic Environmental Biosensing and Energy Storage Devices

The integration of microfluidics and electrochemical cells is at the forefront of emerging sensors and energy systems; however, a fabrication scheme that can create both the microfluidics and electrochemical cells in a scalable fashion is still lacking. We present a one-step, mask-free process to create, pattern, and tune laser-induced graphene (LIG) with a ubiquitous CO₂ laser. The laser parameters are adjusted to create LIG with different electrical conductivity, surface morphology, and surface wettability without the need for postchemical modification. Such definitive control over material properties enables the creation of LIG-based integrated open microfluidics and electrochemical sensors that are capable of dividing a single water sample along four multifurcating paths to three ion selective electrodes (ISEs) for potassium (K⁺), nitrate (NO₃^-), and ammonium (NH₄⁺) monitoring and to an enzymatic pesticide sensor for organophosphate pesticide (parathion) monitoring. The ISEs displayed near-Nernstian sensitivities and low limits of detection (LODs) (10^-5.01 M, 10^-5.07 M, and 10^-4.89 M for the K⁺, NO₃^-, and NH₄⁺ ISEs, respectively) while the pesticide sensor exhibited the lowest LOD (15.4 pM) for an electrochemical parathion sensor to date. LIG was also specifically patterned and tuned to create a high-performance electrochemical micro supercapacitor (MSC) capable of improving the power density by 2 orders of magnitude compared to a Li-based thin-film battery and the energy density by 3 orders of magnitude compared to a commercial electrolytic capacitor. Hence, this tunable fabrication approach to LIG is expected to enable a wide range of real-time, point-of-use health and environmental sensors as well as energy storage/harvesting modules.

Direct Pattern Growth of Carbon Nanomaterials by Laser Scribing on Spin-Coated Cu-PI Composite Films and Their Gas Sensor Application

The excellent physical and chemical properties of carbon nanomaterials render them suitable for application in gas sensors. However, the synthesis of carbon nanomaterials using high-temperature furnaces is time consuming and expensive. In this study, we synthesize a carbon nanomaterial using local laser-scribing on a substrate coated with a Cu-embedded polyimide (PI) thin film to reduce the processing time and cost. Spin coating using a Cu-embedded PI solution is performed to deposit a Cu-embedded PI thin film (Cu@PI) on a quartz substrate, followed by the application of a pulsed laser for carbonization. In contrast to a pristine PI solution-based PI thin film, the laser absorption of the Cu-embedded PI thin film based on Cu@PI improved. The laser-scribed carbon nanomaterial synthesized using Cu@PI exhibits a three-dimensional structure that facilitates gas molecule absorption, and when it is exposed to NO₂ and NH₃, its electrical resistance changes by −0.79% and +0.33%, respectively.

Fabrication of Carbon Nanomaterials Using Laser Scribing on Copper Nanoparticles-Embedded Polyacrylonitrile Films and Their Application in a Gas Sensor

Carbon nanomaterials have attracted significant research attention as core materials in various industrial sectors owing to their excellent physicochemical properties. However, because the preparation of carbon materials is generally accompanied by high-temperature heat treatment, it has disadvantages in terms of cost and process. In this study, highly sensitive carbon nanomaterials were synthesized using a local laser scribing method from a copper-embedded polyacrylonitrile (CuPAN) composite film with a short processing time and low cost. The spin-coated CuPAN was converted into a carbonization precursor through stabilization and then patterned into a carbon nanomaterial of the desired shape using a pulsed laser. In particular, the stabilization process was essential in laser-induced carbonization, and the addition of copper promoted this effect as a catalyst. The synthesized material had a porous 3D structure that was easy to detect gas, and the resistance responses were detected as -2.41 and +0.97% by exposure to NO₂ and NH₃, respectively. In addition, the fabricated gas sensor consists of carbon materials and quartz with excellent thermal stability; therefore, it is expected to operate as a gas sensor even in extreme environments.

Low-Cost Graphene-Based Digital Microfluidic System

In this work, the laser-scribing technique was used as a low-cost, rapid and facile method for fabricating digital microfluidic (DMF) systems. Laser-scribed graphene (LSG) electrodes are directly synthesized on flexible substrates to pattern the DMF electrode arrays. This facilitates the DMF electrodes’ fabrication process by eliminating many microfabrication steps. An electrowetting test was performed to investigate the effectiveness of the LSG DMF electrodes in changing the contact angles of droplets. Different DMF operations were successfully performed using the proposed LSG DMF chips in both open and closed DMF systems. The quality and output resolution were examined to assess the performance of such patterned electrodes in the DMF systems. To verify the efficacy of the LSG DMF chips, a one-step direct assay for the detection of Legionellapneumophila deoxyribonucleic acid (DNA) was performed on the chip without the need for any washing step. The high specificity in distinguishing a single-nucleotide mismatch was achieved by detecting target DNA concentrations as low as 1 nM. Our findings suggest that the proposed rapid and easy fabrication method for LSG DMF electrodes offers a great platform for low-cost and easily accessible point-of-care diagnostic devices.

New Features of Photochemical Decomposition of Hybrid Lead Halide Perovskites by Laser Irradiation

We found that laser irradiation, being widely used in perovskite photovoltaics for both laser scribing and materials characterization, inevitably causes a cascade of complex photo- and thermochemical conjugated reactions, material melting, and ablation with deep morphological and composition changes of perovskite thin films over a much larger area compared to the initial laser spot. A crucial issue in the advancing or suppression of these degradation processes is related to the origin of the surrounding atmosphere. In particular, an effective approach utilizing an inert gas flow directed onto the exposed area is suggested for the first time to eliminate the negative consequences of perovskite laser scribing. This finding is naturally related to experimental observations of spreading the volatile decomposition products, including elemental iodine, over the pristine perovskite material, regardless of its composition, followed by laser-induced formation of liquid polyiodides. Suppression of decomposition product amount by proper selection of the gas atmosphere and power regime of the laser treatment is of interest to enhance the scribing procedure.

Electron Microscopy Characterization of P3 Lines and Laser Scribing-Induced Perovskite Decomposition in Perovskite Solar Modules

Hybrid metal halide perovskites have emerged as a potential photovoltaic material for low-cost thin film solar cells due to their excellent optoelectronic properties. However, high efficiencies obtained with lab-scale cells are difficult to replicate in large modules. The upscaling process requires careful optimization of multiple steps, such as laser scribing, which divides a module into serially connected cells using a pulsed laser beam. In this work, we characterize the effect of laser scribing on the perovskite layer adjacent to a P3 scribe line using analytical scanning and cross-sectional transmission electron microscopy techniques. We demonstrate that lateral flow of residual thermal energy from picosecond laser pulses decomposes the perovskite layer over extended length scales. We propose that the exact nature of the change in perovskite composition is determined by the presence of preexisting PbI₂ grains and hence by the original perovskite formation reaction. Furthermore, we show that along the P3 lines, the indium tin oxide contact is also damaged by high-fluence pulses. Our results provide a deeper understanding on the interaction between laser pulses and perovskite solar modules, highlighting the need to minimize material damage by careful tuning of both laser parameters and the device fabrication procedure.

Wearable Fluid Capture Devices for Electrochemical Sensing of Sweat

Wearable sensing technologies are vital for realizing personalized health monitoring. Noninvasive human sweat sampling is essential for monitoring an individual's physical state using rich physiological data. However, existing wearable sensing technologies lack the controlled capture of body sweat and in performing on-device measurement without inflammatory contact. Herein, we report the development of a wearable sweat-capture device using patterned graphene arrays with controlled superwettability and electrical conductivity for simultaneously capturing and electrochemically measuring sweat droplets. The sweat droplets exhibited strong attachment on the superhydrophilic graphene patterns, even during moderate exercising. The captured sweat droplets present strong electrochemical signals using graphene films as the working electrode and metal pins as the counter electrode arrays assembled on 3D printed holders, at the detection limit of 6 μM for H₂O₂ sensing. This research enables full-body spatiotemporal mapping of sweat, which is beneficial for a broad range of personalized monitoring applications, such as drug abuse detection, athletics performance optimization, and physiological wellness tracking.

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.