Search Results (72)

The multi-layer workpiece and multi-wire electrochemical microfabrication method (MWECM) has considerable potential in improving production efficiency and is considered a promising technology for manufacturing high-quality array microstructures. However, due to the accumulation of electrolytic by-products between workpiece layers, the machining accuracy is relatively low, which still limits its application in industrial environments. To address this issue, this article introduces a method to enhance mass transfer, which involves multi-layer workpieces and multi-wire electrochemical microfabrication, and employs horizontal electrolyte flushing (MWECMF). This innovation promotes the effective discharge of electrolytic deposits, thereby enhancing the renewal of electrolytes within the electrode gap. And use flow field simulation to optimize the interlayer spacing of workpieces and determine the optimal workpiece spacing. In addition, single factor experiments were conducted to determine the optimal processing parameters, including wire feed speed, power supply voltage, frequency, and duty cycle. Finally, at a feed rate of 1.2 µm/s, an array microstructure was successfully fabricated using a two-wire electrode setup and a four-layer workpiece configuration, achieving an overall machining rate of 9.6 µm/s. Compared to traditional tools or workpiece vibration mass transfer, the MWECMF method significantly improves the machining efficiency of wire electrochemical microfabrication (WECM). Full article

Wire electrochemical discharge machining (WECDM) integrates the effectiveness of electrical discharge machining (EDM) with the superior quality of electrochemical machining (ECM), leading to enhanced machining efficiency, excellent surface finish, and significant potential for advancement. However, previous research has mainly focused on the processing of non-metallic materials, with little research in the field of the microfabrication of thick metal materials. The wire electrochemical discharge machining process with large aspect ratios is more complex. Accordingly, a unidirectional traveling wire electrochemical discharge micromachining (UWECDMM) method using a glycol-based electrolyte was proposed. The method employs a glycol solution with low conductivity and a neutral salt, facilitating enhanced mass transfer efficiency through a unidirectional traveling wire, and enabling the realization of high-efficiency, high-precision, and recast-free processing. The phenomenon of discharge in UWECDMM was observed in real-time with a high-speed camera, while the voltage and current waveforms throughout the machining process were carefully analyzed. It was found that electrolysis and discharge alternate. Experiments were conducted to investigate the wire traveling pattern, the recast layer, and the wear of the wire electrode. It was found that due to the small energy of a single discharge, the wear of wire electrodes is minimal after multiple uses and can be reused. Under optimal parameters, a machined surface without a recast layer can be obtained. In the final stages, a standard structure was machined on plates of 10 mm thickness made of pure nickel and 304 stainless steel, using a tungsten wire measuring 30 μm in diameter. The feed rate achieved was 1 μm/s, the surface roughness (Ra) measured 0.06 μm, and the absence of a recast layer confirmed the method’s sustainability and quality traits, indicating significant potential in microfabrication. Full article

Electrode designs and materials have become an increasingly important performance driver for microelectrode arrays, which are among the essential tools for cellular electrophysiology. Ongoing works have continuously innovated over a diverse range of electrode shapes, sizes, and materials. The large design and fabrication parameter space represents rich opportunities for optimizing performance and functionalities as well as a challenge for electrode developers due to a lack of predictive simulation software to aid design works. Electrode prototypes often need to be fabricated, empirically evaluated, and iteratively optimized at significant cost. Efficient hardware testing solutions to aid the development of new electrodes, especially at an early stage when the number of candidate designs is still high, are therefore increasingly important. Here, we propose and implement a cost-effective testbed platform, which is aimed at obtaining first-order characteristics from electrode prototypes to inform early-stage screening and refinement. Upon testing with microfabricated electrodes, the platform was shown to achieve an impedance measurement accuracy comparable to commercial equipment and effectively recorded extracellular action potentials of in vitro rat cortical neurons. By providing relevant electrode testing at a significantly lower cost, in a more compact form, and with greater ease of assembly, compared to existing hardware solutions, the presented testbed can meaningfully lower entry barriers for the development of new array-based electrophysiological microelectrodes. Full article

Terahertz metal rectangular cavity structures are widely used in terahertz devices due to their performance advantages, and various microfabrication techniques have been applied to the manufacturing of their high performance. In this paper, several typical application fields of terahertz technology and the reasons for its application in these fields are elaborated in detail. Several typical terahertz devices with terahertz metal rectangular cavity structures are introduced in detail. The research progress of various micromachining techniques for manufacturing terahertz rectangular cavity structures, such as DRIE, UV-LIGA, micro-milling, LTCC, 3D printing, and electrochemical micromachining, is discussed in detail. Finally, the advantages and disadvantages of various micromachining techniques for manufacturing terahertz micro-rectangular cavity structures are discussed, and the results show that electrochemical micromachining technology and micro-nano 3D printing technology are relatively promising methods for the manufacturing of high-frequency terahertz rectangular cavity structures. Full article

The blood–brain barrier (BBB) is key to the regular functioning of the central nervous system. The dysfunction of the BBB has been described in various neurological disorders, including schizophrenia. Schizophrenia (SCZ) is a chronic psychiatric disorder described by hallucinations, delusions, and negative symptoms. The Olanzapine (OLZ) drug is an electroactive species, and its levels can be monitored using electrochemical sensors. The detection of OLZ was demonstrated previously by using electrochemical sensors, and this technique can be used to monitor the levels of OLZ in real time. The challenge is to identify the permeability of OLZ through the BBB, so a replica model was designed with the BBB based on a Transwell membrane seeded with endothelial cells. A microfabricated electrode consisting of a 3 mm Au disk was modified with platinum black; this enables higher selectivity of electrochemical signals from OLZ. The dose–response of OLZ was characterized in phosphate buffer saline solution (10 mM, pH 7.4) by adding 20–200 nM (in steps 20) of OLZ stock solution. The observed chronoamperometric electrochemical signals showed an increasing current at 0.45 V vs. Ag/AgCl with an increasing OLZ concentration. The controls for the experiments were performed in phosphate-buffered saline solution (10 mM, pH 7.4). The detection limit was calculated as 9.96 ± 7.35 × 10⁻⁶ nM from the calibration curve. The membrane permeability of the OLZ drug tested with five SCZ patients was monitored by studying the TEER measurements and permeability rate constant data. Full article

This review into recent advancements in silicon-based technology, with a particular emphasis on the biomedical applications of silicon sensors. Owing to their diminutive size, high sensitivity, and intrinsic compatibility with electronic systems, silicon-based sensors have found widespread utilization across healthcare, industrial, and environmental monitoring domains. In the realm of biomedical sensing, silicon has demonstrated significant potential to enhance human health outcomes while simultaneously driving progress in microfabrication techniques for multifunctional device development. The review systematically examines the versatile roles of silicon in the fabrication of electrodes, sensing channels, and substrates. Silicon electrodes are widely used in electrochemical biosensors for glucose monitoring and neural activity recording, while sensing channels in field-effect transistor biosensors enable the detection of cancer biomarkers and small molecules. Porous silicon substrates are applied in optical biosensors for label-free protein and pathogen detection. Key challenges in this field, including the interaction of silicon with biomolecules, the economic barriers to miniaturization, and issues related to signal stability, are critically analyzed. Proposed strategies to address these challenges and improve sensor functionality and reliability are also discussed. Furthermore, the article explores emerging developments in silicon-based biosensors, particularly their integration into wearable technologies. The pivotal role of artificial intelligence (AI) in enhancing the performance, functionality, and real-time capabilities of these sensors is also highlighted. This review provides a comprehensive overview of the current state, challenges, and future directions in the field of silicon-based biomedical sensing technologies. Full article

In this paper, enhanced rotational circulation in a circular microfluidic chamber driven by dual focused surface-acoustic-wave (SAW) beams is presented. To characterize the resonant frequency and focusing effect, we simulate the focused SAW field excited by an arc-shaped interdigital transducer patterned on a 128°Y-cut lithium-niobate (LiNbO₃) substrate using a finite element method. A full three-dimensional perturbation model of the combined system of the microfluidic chamber and the SAW device is conducted to obtain the acoustic pressure and acoustic streaming fields, which show rotational acoustic pressure and encircling streaming resulted in the chamber. Accordingly, the SAW acoustofluidic system is realized using microfabrication techniques and applied to perform acoustophoresis experiments on submicron particles suspending in the microfluidic chamber. The result verifies the rotational circulation motion of the streaming flow, which is attributed to enhanced angular momentum flux injection and Eckart streaming effect through the dual focused SAW beams. Our results should be of importance in driving particle circulation and enhancing mass transfer in chamber embedded microfluidic channels, which may have promising applications in accelerating bioparticle or cell reactions and fusion, enhancing biochemical and electrochemical sensing, and efficient microfluidic mixing. Full article

The measurement of cardiac troponin I (cTnI) is of vital importance for the early diagnosis of acute myocardial infarction. In this study, an enhanced electrochemiluminescent immunoassay for the highly sensitive and precise determination of cTnI was reported. A biomimetic chip with nepenthes peristome surface microstructures to achieve single-layer microbead arrays and integrated microelectrode arrays (MEAs) for ECL detection was microfabricated. Ru@SiO₂ nanoparticles were prepared as signal amplificators labeling immunomagnetic beads. Dendrimer-encapsulated platinum nanoparticles (Pt DENs) were electrochemically modified on ITO MEAs. The resulting Pt DEN-modified ITO MEAs preserved good optical transparency and exhibited an approximately 20-fold ECL signal amplification compared to that obtained from bare ITO. The method made full use of the biomimetic chip with Pt DENs to develop single-layer immunomagnetic bead arrays with increasingly catalyzed electrochemical oxidation of the [Ru(bpy)₃]²⁺–TPA system. Consequently, a limit of detection calculated as 0.38 pg/mL (S/N = 3) was obtained with excellent selectivity, demonstrating significant potential for the detection of cTnI in clinical diagnostics. Full article

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. Full article

Microbial foodborne pathogens present significant challenges to public health and the food industry, requiring rapid and accurate detection methods to prevent infections and ensure food safety. Conventional single biosensing techniques often exhibit limitations in terms of sensitivity, specificity, and rapidity. In response, there has been a growing interest in multimodal biosensing approaches that combine multiple sensing techniques to enhance the efficacy, accuracy, and precision in detecting these pathogens. This review investigates the current state of multimodal biosensing technologies and their potential applications within the food industry. Various multimodal biosensing platforms, such as opto-electrochemical, optical nanomaterial, multiple nanomaterial-based systems, hybrid biosensing microfluidics, and microfabrication techniques are discussed. The review provides an in-depth analysis of the advantages, challenges, and future prospects of multimodal biosensing for foodborne pathogens, emphasizing its transformative potential for food safety and public health. This comprehensive analysis aims to contribute to the development of innovative strategies for combating foodborne infections and ensuring the reliability of the global food supply chain. Full article

Using DNA as the next-generation medium for data storage offers unparalleled advantages in terms of data density, storage duration, and power consumption as compared to existing data storage technologies. To meet the high-speed data writing requirements in DNA data storage, this paper proposes a novel design for an ultra-high-density and high-throughput DNA synthesis platform. The presented design mainly leverages two functional modules: a dynamic random-access memory (DRAM)-like integrated circuit (IC) responsible for electrode addressing and voltage supply, and the static droplet array (SDA)-based microfluidic structure to eliminate any reaction species diffusion concern in electrochemical DNA synthesis. Through theoretical analysis and simulation studies, we validate the effective addressing of 10 million electrodes and stable, adjustable voltage supply by the integrated circuit. We also demonstrate a reaction unit size down to 3.16 × 3.16 μm², equivalent to 10 million/cm², that can rapidly and stably generate static droplets at each site, effectively constraining proton diffusion. Finally, we conducted a synthesis cycle experiment by incorporating fluorescent beacons on a microfabricated electrode array to examine the feasibility of our design. Full article

This study aims to develop a microelectrode array-based neural probe that can record dopamine activity with high stability and sensitivity. To mimic the high stability of the gold standard method (carbon fiber electrodes), the microfabricated platinum microelectrode is coated with carbon-based nanomaterials. Carboxyl-functionalized multi-walled carbon nanotubes (COOH-MWCNTs) and carbon quantum dots (CQDs) were selected for this purpose, while a conductive polymer like poly (3-4-ethylene dioxythiophene) (PEDOT) or polypyrrole (PPy) serves as a stable interface between the platinum of the electrode and the carbon-based nanomaterials through a co-electrodeposition process. Based on our comparison between different conducting polymers and the addition of CQD, the CNT–CQD–PPy modified microelectrode outperforms its counterparts: CNT–CQD–PEDOT, CNT–PPy, CNT–PEDOT, and bare Pt microelectrode. The CNT–CQD–PPy modified microelectrode has a higher conductivity, stability, and sensitivity while achieving a remarkable limit of detection (LOD) of 35.20 ± 0.77 nM. Using fast-scan cyclic voltammetry (FSCV), these modified electrodes successfully measured dopamine’s redox peaks while exhibiting consistent and reliable responses over extensive use. This electrode modification not only paves the way for real-time, precise dopamine sensing using microfabricated electrodes but also offers a novel electrochemical sensor for in vivo studies of neural network dynamics and neurological disorders. Full article

Amorphous alloy (AA) is a high-performance metal material generally with significantly excellent mechanical and corrosion resistance properties and thus is considered as a desirable material selection for micro-scale articles. However, the microfabrication of AA still faces a variety of technical challenges mainly because the materials are too hard to process and easily lose their original properties, although at moderately high temperatures. In this study, jet-electrolyte electrochemical machining (Jet-ECM) was proposed to microfabricate the Zr-based AA because it is a low-temperature material-removal process based on the anode dissolution mechanism. The electrochemical dissolution characteristics and material removal mechanism of AA were investigated, and then the optimal process parameters were achieved based on the evaluation of the surface morphologies, surface roughness, geometrical profile, and machining accuracy of the machined micro-dimples. Finally, the feasibility was further studied by using Jet-ECM to fabricate arrayed micro-dimples using the optimized parameters. It was found that Jet-ECM can successfully microfabricate mirror-like surface AA arrayed precision micro-dimples with significantly high dimensional accuracy and geometrical consistency. Jet-ECM is a promisingly advantageous microfabrication process for the hard-to-machine AA. Full article

Flexible multielectrode arrays with glassy carbon (GC) electrodes and metal interconnection (hybrid MEAs) have shown promising performance in multi-channel neurochemical sensing. A primary challenge faced by hybrid MEAs fabrication is the adhesion of the metal traces with the GC electrodes, as prolonged electrical and mechanical stimulation can lead to adhesion failure. Previous devices with GC electrodes and interconnects made of a homogeneous material (all GC) demonstrated exceptional electrochemical stability but required miniaturization for enhanced tissue integration and chronic electrochemical sensing. In this study, we used two different methods for the fabrication of all GC-MEAs on thin flexible substrates with miniaturized features. The first method, like that previously reported, involves a double pattern-transfer photolithographic process, including transfer-bonding on temporary polymeric support. The second method requires a double-etching process, which uses a 2 µm-thick low stress silicon nitride coating of the Si wafer as the bottom insulator layer for the MEAs, bypassing the pattern-transfer and demonstrating a novel technique with potential advantages. We confirmed the feasibility of the two fabrication processes by verifying the practical conductivity of 3 µm-wide 2 µm-thick GC traces, the GC microelectrode functionality, and their sensing capability for the detection of serotonin using fast scan cyclic voltammetry. Through the exchange and discussion of insights regarding the strengths and limitations of these microfabrication methods, our goal is to propel the advancement of GC-based MEAs for the next generation of neural interface devices. Full article

In this work, we describe a new type of electrochemical aptasensor for the label-free detection of oxytetracycline (OTC). Thin-film gold electrodes were fabricated through sputtering gold on a Kapton film, followed by the immobilization of a thiol-modified aptamer on the electrode surface. The selective capture of OTC at the aptamer-functionalized electrodes was monitored electrochemically with the use of the [Fe(CN)₆]⁴⁻/[Fe(CN)₆]³⁻ redox probe. Different experimental variables were studied, through which the metrological features for OTC determination were derived. Finally, the developed sensor was implemented to achieve the detection of OTC in a spiked milk sample. Full article