Gou-Jen Wang

Neural-network-based self-tuning PI controller for precise motion control of PMAC motors

In general, proportional plus integral (PI) controllers used in computer numerically controlled machines possess fixed gain. They may perform well under some operating conditions, but not all. To increase the robustness of fixed-gain PI controllers, we propose a new neural-network-based self-tuning PI control system. In this new approach, a well-trained neural network supplies the PI controller with suitable gain according to each operating condition pair (torque, angular velocity, and position error) detected. To demonstrate the advantages of our proposed neural-network-based self-tuning PI control technique, both computer simulations and experiments were executed in this research. During the computer simulation, the direct experiment method was adopted to better model the problem of hysteresis in the AC servo motor. In real experiments, a PC-based controller was used to carry out the control tasks. Results of both computer simulations and experiments show that the newly developed dynamic PI approach outperforms the fixed PI scheme in rise time, precise positioning, and robustness.

A fast multilayer neural-network training algorithm based on the layer-by-layer optimizing procedures

A faster new learning algorithm to adjust the weights of the multilayer feedforward neural network is proposed. In this new algorithm, the weight matrix (W(2)) of the output layer and the output vector (Y) of the previous layer are treated as two variable sets. An optimal solution pair (W(2)*,Y(P)*) is found to minimize the sum-square-error of the patterns input. Y(P)* is then used as the desired output of the previous layer. The optimal weight matrix and layer output vector of the hidden layers in the network is found with the same method as that used for the output layer. In addition, the dynamic forgetting factors method makes the proposed new algorithm even more powerful in dynamic system identification. Computer simulation shows that the new algorithm outmatches other learning algorithms both in converging speed and in computation time required.

Fabrication of PLGA microvessel scaffolds with circular microchannels using soft lithography

A simple micromolding method for fabricating PLGA (poly(lactic-co-glycolic acid)) microstructures made up of microchannels with a circular cross-section is presented. The thermal reflow technique is adopted to fabricate the semi-cylindrical photoresist master. The PLGA solution is prepared by dissolving PLGA polymer in acetone and then casting the solution onto the semi-cylindrical photoresist master to produce PLGA microstructures. Two PLGA membranes are bonded together to form microstructures consisting of circular microchannels. A microvessel scaffold suitable for tissue engineering was fabricated using the proposed method, and bovine endothelial cells were cultured into the scaffold by semi-dynamic seeding. The cell stain Calcein-AM was used to overcome the problem of the PLGA scaffolds becoming opaque, which in the past had made it difficult to effectively monitor the progress of cell seeding.

Synthesis of antibacterial TiO2/PLGA composite biofilms

UNLABELLED This study developed a TiO2/PLGA [poly(lactic-co-glycolic acid)] composite biomaterial, which possesses antibacterial properties but is biocompatible, for artificial dressing applications. A sol-gel method was used for the preparation of the nano TiO2 powder with anatase phase. Several concentration ratios of TiO2 versus PLGA were analyzed to optimize the disinfection efficiency of the composite biomaterial. The antibacterial activity of the fabricated TiO2/PLGA composite was measured against Staphylococcus aureus and Escherichia coli. To evaluate the feasibility of the biomaterial on wound healing in vitro, human keratinocytes (HaCaTs), fibroblasts (L929s), and bovine carotid artery endothelial cells (BECs) were seeded on the TiO2/PLGA composite biofilms. To investigate the histological effect of the biocompatible biofilm in vivo, a rat subcutaneous implantation was performed. Our results show that TiO2/PLGA composite biofilms containing 10% TiO2 nanoparticles have an effective antibacterial property, a good survival rate on HaCaTs and L929s, and relative safe stability in tissue implantation. FROM THE CLINICAL EDITOR This study reports the development of titanium dioxide-polylactic-co-glycolic acid composite biofilms, which possess antibacterial properties and are biocompatible for dressing applications, as demonstrated in a model system.

Highly sensitive glucose biosensor based on Au–Ni coaxial nanorod array having high aspect ratio

An effective glucose biosensor requires a sufficient amount of GOx immobilizing on the electrode surface. An electrode of a 3D nanorod array, having a larger surface-to-volume ratio than a 2D nanostructure, can accommodate more GOx molecules to immobilize onto the surface of the nanorods. In this study, a highly sensitive Au-Ni coaxial nanorod array electrode fabricated through the integration of nano electroforming and immersion gold (IG) method for glucose detection was developed. The average diameter of the as-synthesized Ni nanorods and that of the Au-Ni nanorods were estimated to be 150 and 250 nm, respectively; both had a height of 30 μm. The aspect ratio was 120. Compared to that of a flat Au electrode, the effective sensing area was enhanced by 79.8 folds. Actual glucose detections demonstrated that the proposed Au-Ni coaxial nanorod array electrode could operate in a linear range of 27.5 μM-27.5mM with a detection limit of 5.5μM and a very high sensitivity of 769.6 μA mM(-1)cm(-2). Good selectivity of the proposed sensing device was verified by sequential injections of uric acid (UA) and ascorbic acid (AA). Long-term stability was examined through successive detections over a period of 30 days.

ZnO-Nanorod Dye-Sensitized Solar Cells: New Structure without a Transparent Conducting Oxide Layer

Conventional nanorod-based dye-sensitized solar cells (DSSCs) are fabricated by growing nanorods on top of a transparent conducting oxide (TCO, typically fluorine-doped tin oxide—FTO). The heterogeneous interface between the nanorod and TCO forms a source for carrier scattering. This work reports on a new DSSC architecture without a TCO layer. The TCO-less structure consists of ZnO nanorods grown on top of a ZnO film. The ZnO film replaced FTO as the TCO layer and the ZnO nanorods served as the photoanode. The ZnO nanorod/film structure was grown by two methods: (1) one-step chemical vapor deposition (CVD) (2) two-step chemical bath deposition (CBD). The thicknesses of the nanorods/film grown by CVD is more uniform than that by CBD. We demonstrate that the TCO-less DSSC structure can operate properly as solar cells. The new DSSCs yield the best short-current density of 3.96 mA/ c m 2 and a power conversion efficiency of 0.73% under 85 mW/ c m 2 of simulated solar illumination. The open-circuit voltage of 0.80 V is markedly higher than that from conventional ZnO DSSCs.

A novel nanostructured biosensor for the detection of the dust mite antigen Der p2

The group 2 allergen, Der p2, has been reported to activate innate toll-like receptors (TLRs) on respiratory epithelial cells and thus aggravate respiratory diseases. In this study, a highly sensitive nanostructured biosensor based on a 3D sensing element with uniformly deposited gold nanoparticles is proposed for the detection of the dust mite antigen Der p2. The barrier layer comprises an anodic aluminum oxide (AAO) film which is used as the template in this highly sensitive nanostructured biosensor. Simple electrochemical deposition without reducing agent and stabilizer was enough to uniformly synthesize gold nanoparticles on the surface of the barrier layer. The size and the distribution density of the nanoparticles can be well controlled by the applied potential during electrochemical deposition. Following this procedure, the dust mite monoclonal antibodies (IgG) were then immobilized through the 11-MUA (11-mercaptoundecanoic acid), (1-ethyl-3-(3-dimethyl-aminopropyl)-carbodiimide)/(N-hydroxysuccinimide) self-assembled monolayer approach for the dust mite antigen Der p2 detection. The detection limit of the proposed 3D gold nanoparticle-based nanostructured biosensor was examined using electrochemical impedance spectroscopy analysis and found to be 1 pg/mL. The dynamic range was found to be 5 μg/mL. The proposed nanostructured biosensor would be useful for fast detection of rare molecules in a solution.

Electrophoretic deposition of uniformly distributed TiO2 nanoparticles using an anodic aluminum oxide template for efficient photolysis

In this study, a novel method for fabricating a high efficiency titanium dioxide photocatalyst is presented. Radio frequency (RF) magnetron sputtering was employed to grow 3D nano-structured Au thin films using the barrier-layer side of anodic aluminum oxide (AAO) as the template. The template was prepared by immersing this side of an AAO film into a 30 wt% phosphoric acid solution to modify the surface of the barrier layer in such a manner that a contrasting surface was obtained. The electrophoretic deposition method was then implemented to uniformly deposit TiO(2) nanoparticles on the 3D nano-structured Au electrode. The efficiency of the proposed photocatalyst, in terms of the photolysis efficiency, was measured using proton-motive-force driving chloroplastmimic photovoltaics. Experiments were carried out to demonstrate the photolysis efficiency of the proposed 3D nano-structured TiO(2) photocatalyst, which showed a 10-fold increase over that of Degussa P25 plane TiO(2). The photocurrent could be further enhanced by the deposition of a sensitized dye, such as N3, which extended the absorption spectrum from the UV range to the visible light range.

Polymerase chain reaction-free detection of hepatitis B virus DNA using a nanostructured impedance biosensor.

A polymerase chain reaction (PCR)-free technique for the effective detection of genomic length hepatitis B virus (HBV) DNA is described in this study. The honeycomb-like barrier layer of an anodic aluminum oxide (AAO) film having a uniform nanohemisphere array was used as the substrate of the sensing electrode. A 30-nm gold film was sputtered onto the AAO barrier layer surface as the electrode, followed by electrochemical deposition of gold nanoparticles (GNPs) on the hemisphere surface. A specially designed single-strand 96-mer gene fragment of the target genomic DNA of HBV based on the genome sequences of HBV was immobilized on the nanostructured electrode as the capture probe. Target HBV DNA obtained from clinical samples was hybridized to the sensing probes. Detection results illustrate two dynamic linear ranges, 10(2)-10(3) and 10(3)-10(5.1) copies/mL, having R(2) values of 0.801 and 0.996 could be obtained, respectively. The detection limit of the proposed sending scheme was measured to be 111 copies/mL. The total of 45 target samples, including 20 samples with HBV concentration being lower than 10(2) copies/mL and 25 samples with HBV concentration being in the range of 10(3)-10(5.1) copies/mL, were used for real test. The concentration of these 45 HBV DNA samples was measured by the COBAS Ampliprep system. Comparing the measured results of the COBAS Ampliprep and our system, it was illustrated that the HBV DNA concentrations measured by the proposed method in this study had a high linear correlation with the COBAS Ampliprep, having R(2) values of 0.983. The proposed sensing scheme is highly feasible for future clinical applications.

Nanostructured electrochemical biosensor for th0065 detection of the weak binding between the dengue virus and the CLEC5A receptor

UNLABELLED In this paper, we develop an effective method for detecting weak molecular bonding between the dengue virus (DV) and its receptor C-type lectin domain family 5, member A (CLEC5A). The CLEC5A-DV interaction is critical for DV-induced hemorrhagic fever and shock syndrome, so the sensing of CLEC5A-DV binding is crucial to realize a thorough study of the pathogenesis of dengue fever. Through a highly sensitive nanostructured sensing electrode of gold nanoparticles (GNPs) uniformly deposited on a nanohemisphere array, a label-free detection of the ultra weak binding between CLEC5A and the DV can be performed with electrochemical impedance spectroscopy (EIS). Experimental results demonstrate that the proposed approach is a highly promising method for investigating weak molecular interactions such as the ligand-receptor interaction of dengue fever, enterovirus (EV), or the interaction between cancer surface glycoproteins and their receptors. FROM THE CLINICAL EDITOR Authors of this study investigated the ultra-weak binding between dengue virus and its CLEC5A receptor via electrochemical impedance spectroscopy and gold NP sensing electrode. Similar methods may be applicable in other infections and in cancer models as well.