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Graphene represents a high-performance material for field effect transistor (FET) manufacture. As a monolayer of carbon atoms, graphene offers flexibility, high carrier mobility, and transparency. Solution-gated graphene FETs based on flexible substrates have been developed for various applications. However, none of these FETs offer both flexibility and good insulation from the electrolyte simultaneously. This would restrict their applicability in certain areas, such as implantation. To solve this problem, we used commercially available graphene and polyimide to fabricate a graphene FET. Photosensitive polyimide was used as both substrate and insulator for our device. Two Au electrodes were used separately as source and drain, and the graphene was exposed to an electrolytic solution to form a solution-gated structure. In this paper, we have studied the resistance variation between source and drain during specific fabrication steps to optimize the fabrication process. By analyzing the FET performance after repeated bending tests, our device's performance reliability was also confirmed. When compared with similar published flexible devices, our FET showed higher transconductance and lower noise levels. Also, neural activities were recorded from cortex neurons cultured on graphene FET for the first time, which proved our device's biocompatibility and demonstrated its potential for electrophysiological applications. $\hfill[{2013\hbox{-}0025}]$

To achieve long-term effectiveness of implanted neural prostheses, we developed a simple and low-cost fabrication process for flexible neural microelectrodes integrated with microfluidic channels for simultaneous drug delivery and multi-channel stimulation. In this process, a conventional thin-film electrode fabrication procedure is combined with poly(dimethylsiloxane) molding and a bonding technique. Compared with the current fabrication method, this process significantly reduces the cost and time needed for fabrication. The microelectrodes were characterized by optical microscopy, impedance measurements and diffusion tests. A numerical simulation was also performed to demonstrate the fluid dynamics of drug release through the microchannels and evaluate the device's performance in terms of its delivery rate and efficiency. The results show that the drug release rate is about 20% of the total amount per day in the first two days and about 4% of the total amount per day in each of the next 10 days. The release process can last more than 2 weeks. The result meets the requirement for long-term release and sufficient drug loading.

An integrated detection circuitry based on a lock-in amplifier was designed for contactless conductivity determination of heavy metals. Combined with a simple-structure electrophoresis microchip, the detection system is successfully utilized for the separ

Hepatitis B is a major disease that causes serious public health problems worldwide. In this study, a visual DNA microarray was developed for the sensitive and specific detection of hepatitis B virus DNA (HBV-DNA) and its single nucleotide polymorphisms. 5′-End-amino-modified oligonucleotide, which was immobilized on microarray surface acted as capture probe, and another part of gold nanoparticles (AuNPs)-labeled oligonucleotide were designed to bind specifically with complementary targets HBV-DNA in the first place, and then linked as a single-strand DNA via Taq DNA ligase. The black image of microarray spots, resulting from silver stain on AuNPs, was used to visually detect target HBV-DNA and its single nucleotide polymorphisms. Capture probe with single base mismatch was prepared to detect the specificity and sensitivity of hybridization on microarray. Target HBV-DNA of different concentrations had been tested. The result indicated that this method has high sensitivity (ac. 10 pM) and specificity in the discrimination of single nucleotide polymorphisms. There is also an evident linear relationship between the signal intensity of microarray spots and the concentration of target DNA at the range of 10–100 pM. This visual detecting technique has great potential in clinical sittings because of its high sensitivity and good specificity.

The technique of microchip gel electrophoresis (MCGE) was used to analyze the polymerase chain reaction (PCR) products of M. tuberculosis Genome stained by ethidium bromide. The electrophoretic process was completed within 3–4 min and the results show that the technique of microchip electrophoresis is a high-speed and high-sensitivity analyzing method.

In microchip electrophoresis (μ-CE), sample injection is generally achieved through cross, double-T, or T-form injector structures. In these reported approaches, the separation efficiency and detection sensitivity of μ-CE is significantly influenced by the shape and size of the sample plug introduced into the separation channel or sample leakage in separation phase. Here, we present a sandwich-injection method for controlling discrete sample injection in μ-CE. This method involves four accessory arm channels in which symmetrical potentials are loaded to form a unique parallel electric field distribution at the intersection of sample and separation channels. The parallel electric field effectuate a virtual wall to confine the shape of a sample plug and depress the spreading of the sample plug at the junction of sample and separation channels, and also prevent sample leakage during separation step. The key features of this method are the ability to inject well-defined sample plugs at the original sample concentration and the ability to control the sample plug size. The virtues of the novel injection technique were demonstrated with numerical models and validated with fluorescence visualizations of electrophoretic experiments.

In this paper, we present a simple, rapid, and low-cost procedure for fabricating glass microfluidic chips. This procedure uses commercially available microscopic slides as substrates and a thin layer of AZ 4620 positive photoresist (PR) as an etch mask for fabricating glass microfluidic components, rather than using expensive quartz glasses or Pyrex glasses as substrates and depositing an expensive metal or polysilicon/amorphous silicon layer as etch masks in conventional method. A long hard-baking process is proposed to realize the durable PR mask capable of withstanding a long etching process. In order to remove precipitated particles generated during the etching process, a new recipe of buffered oxide etching with addition of 20% HCl is also reported. A smooth surface microchannel with a depth of more than 110 mum is achieved after 2 h of etching. Meanwhile, a simple, fast, but reliable bonding process based on UV-curable glue has been developed which takes only 10 min to accomplish the efficient sealing of glass chips. The result shows that a high bonding yield (~ 100%) can be easily achieved without the requirement of clean room facilities and programmed high-temperature furnaces. The presented simple fabrication process is suitable for fast prototyping and manufacturing disposable microfluidic devices.

The ability to culture individual neurons and direct their connections on functional interfaces provides a platform for investigating information processing in neuronal networks. Numerous methods have been used to design ordered neuronal networks on microelectrode arrays (MEAs) for neuronal electrical activities recording. However, so far, no method has been implemented, which simultaneously provides high-resolution neuronal patterns and low-impedance microelectrode. To achieve this goal, we employed a chemical vapor-deposited, non-fouling poly (ethylene) glycol (PEG) self-assembled monolayer to provide a cell repellant background on the MEAs. Photolithography, together with plasma etching of the PEG monolayer, was used to fabricate different patterns on MEAs. No electrode performance degradation was observed after the whole process. Dissociated cortical neurons were cultured on the modified MEAs, and the patterns were maintained for more than 3 weeks. Spontaneous and evoked neuronal activities were recorded. All of the results demonstrate this surface engineering strategy allows successful patterning of neurons on MEAs, and is useful for future studies of information processing in defined neuronal networks on a chip.

Objective: Procyanidins (PC) are widely available natural polyphenols. The present study is designed to investigate if PC can inhibit angiogenesis in lung adenocarcinoma xenografts through crosslinking vascular extracellular matrix (ECM) and preventing proteolysis by matrix metalloproteinases (MMPs). Methods: Using the in vitro MMP-2 proteolysis and in vivo subcutaneous implantation models, we investigated if PC crosslinking inhibits MMP-mediated proteolysis. Using a cultured cell detachment assay, an in vitro angiogenesis assay, and a cell proliferation assay, we investigated if PC inhibits MMP-2-mediated endothelial cell detachment, angiogenesis, and cell proliferation, respectively. Using tumor xenografts, we evaluated if PC can inhibit growth of lung adenocarcinoma. Results: PC crosslink vascular ECM proteins, protecting them against proteolysis by MMPs in vitro and in vivo, protecting cultured human umbilical vein endothelial cells from detachment by MMP-2, and inhibiting in vitro angiogenesis. However, PC (0.75-100 μg/ml) did not inhibit vascular and tumor cells proliferation. PC injections (30 mg PC/kg bodyweight) in situ had anticancer effects on xenografts of lung adenocarcinoma, most likely by inhibiting angiogenesis during ECM proteolysis by MMPs. Conclusion: The results suggest that PC may be important MMP inhibitors that can be used as therapeutic anticancer agents.

We propose how to explore the Franck-Condon (FC) physics via a single ion confined in a spin-dependent potential, formed by the combination of a Paul trap and a magnetic field gradient. The correlation between electronic and vibrational degrees of freedom, called as electron-vibron coupling, is induced by a nonzero gradient. For a sufficiently strong electron-vibron coupling, the FC blockade of low-lying vibronic transitions takes place. We analyze the feasibility of observing the FC physics in a single trapped ion, and demonstrate various potential applications of the ionic FC physics in quantum state engineering and quantum information processing., Comment: 7 pages, 5 figures

Fraction collection following electrophoresis has many applications in biology analysis. These assays typically need to identify specific fractions in the separated sample for further processing and require extraction of one or a group of fragments. Unfortunately, the conventional methods involve cumbersome procedures and are not amenable to integration, automation, and extraction of microscale samples. In this work, we present a scheme of chip-based electroelution for the extraction of DNA fragments, which allows the isolation and collection of target DNA fragments in a single device. Both theoretical analysis and experimental results have shown that there are some cross-contaminations from adjacent bands and a little loss of DNA recovery during target DNA extraction with the prototype miniaturized device. In order to improve the purity and yield of the extracted DNA fragment, an optimal channel configuration for DNA recovery miniaturized device was proposed. The simulations and the experimental results are in good agreement and confirm that with the optimized device design a high-efficiency DNA extraction is achieved.

To establish a method for the detection of isoniazid resistance-associated mutations in katG gene and inhA gene in Mycobacterium tuberculosis with single-stranded conformation polymorphism (SSCP) analysis by the micro-channel electrophoresis chip system.The polymer solutions of acrylamide and its derivatives were used for sieving matrices with small amount of acridine orange as the fluorescent tag. A novel pair of primers was designed to link an extra segment that could be base paired with the mutation region to the PCR products of wild type inhA gene, which made the single strands of wild type inhA fragments present a unique conformation.The wild type fragments of katG gene and the fragments with mutation at codon 315 can be distinguished, and the inhA fragments with wild type and mutated regulatory sequence can be distinguished by this method. Twenty-two out of the 23 resistant strains were detected from 30 clinical isolates, the efficiency being 95%.It is demonstrated the high speed and sensitivity in detecting the mutations of isoniazid-resistant genes in Mycobacterium tuberculosis by micro-channel electrophoresis, and this method may be applicable in clinical detection of isoniazid-resistant strains.

This paper presents a signal process method for detection of micro-channel electrophoresis. It was developed and optimized using a laser induced fluorescence (LIF) based detection system. In this detection system, signal was sampled and processed through a novel signal process module. We have used this system to DNA segments separation. The result shows that this signal process method can provide good signal-to-noise ratios.

The quantum kicked top is an important model in quantum chaos, which has recently been simulated by an ensemble of atoms in a magnetic-optical trap (Chaudhury et al 2009 Nature 461 768). We propose an alternative scheme to simulate such a model with trapped ions using unconventional geometric quantum gates, and we consider how to measure the fidelity decay to show the success of the simulation. The experimental feasibility of our scheme is discussed.