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Hydrogen has been recognized as a future energy carrier that may allow a gradual transformation from a fossil fuel-based economy to a hydrogen economy. One of main obstacles to implement hydrogen economy is efficient storage of hydrogen. Up to present, none of proposed storage methods completely satisfy all department of energy (DOE) target criteria with gravimetric capacity ~5.5 wt% and loss rate 0.1 (g/h)/kg for hydrogen storage yet. Here we demonstrate high density of hydrogen nano-bubble (HNB) up to ~3.4±0.18 wt% can be efficiently generated and stored via an electron radiolysis assisted abstraction reaction (RAAR) in an encapsulated quasi-2D water reservoir containing organic molecules. The RAAR is a reaction between radiolytic water species and the surface groups of organic molecules. In our system, the long term stability of HNB comes from supersaturation of hydrogen molecules controllable by the electron dose rate and concentration of the organic molecule. The best gravimetric capacity and loss rate in our experiment are ~3.4±0.18 wt% and 0.18(g/h)/kg, respectively, in 25 °C and at 1 bar which fall closely to the DOE targets. A TEM equipped with a continuous flow holder with a quasi-2D water reservoir is utilized for in-situ generation and storage of HNB. The regeneration time for HNB formation is in the order of a few ten seconds. This process can be linked with the microbial electrolysis cell technology that converts hydrogen from wastewater containing abundant organics.

To realize the detection of pesticide, this study developed a paper-based chip involving a 2D to 3D flow channel and automatic time delay for detecting pesticides. The time delay was controlled by different pullulan concentrations. The 3D channel was fabricated by hot embossing (optimized printing parameters were 28 kg at 80°C, and Advantec No. 1 filter paper was used) and transfer printing the hydrophobic material into the paper. Finally, the limit of the detected concentration of the pesticide was 4 ng/mL, which was achieved using 250 U/mL of acetylcholinesterase (AChE) and 2.5% pullulan solution.

In this research, a novel multidimensional prism with three distinct 45°, 135°, and 225° inclined optical surfaces were realized by using inclined exposure technology and SU-8 polymer. To obtain a smooth surface, the solvent loss percentage and temperature of post-exposure bake (PEB) are two key factors that need to be well controlled during fabrication. The experimental results showed that surface roughness can achieve 42.9±7.6 nm, which is one-tenth of high-precision machining or molding processes, under the processes parameter combinations of PEB temperature, and solvent loss percentage is 95°C and 82.86%, respectively. The surface reflectivity of the prism was measured by using a He–Ne laser, and reflectivity of the prism surface without and with aluminum metal film was 90.8% and 91.8%, respectively. The slight difference of reflectivity means that a prism with a high-quality inclined surface can be realized. The functionality of the prism for three lasers was also verified with RGB lasers, and it successfully demonstrated the feasibility of application of a multidimensional prism on the optical system. Finally, the utilization of inclined exposure technology not only monolithically integrates three 45° inclined surfaces into one prism without precision assembly but also greatly simplifies the fabrication processes to further reduce the cost. This component and technology can also be applied to medical endoscope systems if the SU-8 is replaced by PDMS or other biocompatible materials using a molding process. These results provide the potential for mass manufacturing, which is of considerable value to the optical markets.

The use of antibodies against surrogate peptides for target protein enrichment combined with stable isotope standards is one of the important steps in the quantitative analysis of protein samples via mass spectrometry. Currently, commercially available automated instruments such as KingFisher™ are used to perform immunoprecipitation, wash, and elution of protein samples using magnetic beads and immune reactions. However, the use of these instruments for protein or peptide purification takes over 2 h. Moreover, numerous samples (e.g., 96) need to be processed at once to meet the operating cost, and the consumables used in conjunction with them are expensive. Thus, this study developed an automated microfluidic chip that could rapidly purify target peptides in saliva samples within 50 min. The chip is made of five connected pneumatic micromixers that automate the immunoprecipitation of target peptide from the samples. Under optimum operating conditions of 5 Hz and −75 kPa, the recovery rate of peptides achieved by the micromixer in an operating time of 30 min was similar to that achieved by KingFisher™ in the standard operating time of 2 h. The chip-processed samples could be used for the quantitative detection of the oral cancer biomarker protein MMP1 via mass spectrometry with a detection limit of 6.75 ng/mL. Six saliva samples were used to verify the feasibility of the chip for clinical sample use. The MMP1 concentration measured using our sample treatment method was comparable to that treated using a commercially available instrument.

In this work, a way to identify the performance and adjustment of the gripper was proposed by isocline analysis. This isocline analysis method is processed in three steps. Initially, the performance of the original gripper was tested, followed by adjusting the size factors of the gripper, and finally the boundary curve of the catch range was translated inside. Through these three steps, three results were obtained. First, the original performance of the gripper by step 1 was understood, then the difference between the adjusted gripper and the original gripper by step 2 was noted, and finally, the best position or boundary for this gripper by step 3 was identified. This is a feasible performance test, and it has three advantages. Most important of all, the working range of the gripper is understood. Moreover, the most appropriate working position of the gripper is identified. The results showed that the obtained gripper has the potential to improve performance.

A sensitivity silicon p-n diodes for detecting backscattering electrons in SEM was proposed and fabricated. The multi-annular configuration enables to provide higher sensitivity of Z-contrast and better surface topography contrast of BSE image. In this study, the multi-annular backscattered electron detector (BSED) can provide enhancement of surface topography contrast and image contrast with 105% and 42% as compared with commercial BSED which with the multi-fan configuration. We also designed a high sensitivity to low energy electrons detector which with lateral p-n junctions and Al metal grids.

Recently, cold atmospheric-pressure (CAP) plasma have become a novel and popular tools in biomedical applications. It has been proved that CAP plasma treatment will induce cancer cells death. With different CAP plasma treatment parameters, cells will have different fate including proliferation, apoptosis and cell membrane damage. It has been reported that a low energy plasma will cause cell proliferation while a longer exposures lead to cell death. So, the aim for this study is to induce melanoma cells apoptosis in a short time by CAP plasma-jet. We first evaluate the optimal working condition of CAP plasma-jet including treatment time, voltage, flow-rate and plasma-gas composition. Then we use CAP plasma-jet treat on melanoma cells with different medium volume, cell number and treating times to find a suitable condition for the cell culture. Results demonstrate that with medium 0.6 ml and seeding 104 cells have highest cell viability while treat 180 s and 360 s are significantly decreased. In the migration assay, cells migration ability is both decreased when treat with plasma for 180 s and 360 s. We also do the Hoechst 33258 stain, after treating with CAP plasma melanoma cells are detach from the bottom and have DNA condensation. Finally, we examine ROS expression present/ absent ROS inhibitor sodium pyruvate (SP). Data shows that after CAP plasma treatment ROS expression is induced while cell viability is reduced. But cell viability is recovered by pretreat with ROS inhibitor SP. In conclusion, both cell viability and cell migration ability are inhibited by CAP plasma-jet via ROS mediation in melanoma cells.

The purpose of this study was to develop a microelectromechanical systems compatible process (e.g., etching, lithography, sputtering) for a polyimide (PI) substrate. A thin-film transistor (TFT) array on the flexible substrate was demonstrated by fully etching aluminum (Al), indium gallium zinc oxide (IGZO), and aluminum oxide (Al 2 O 3 ). Moreover, during the sputtering process, the surface roughnesses of the IGZO, Al 2 O 3 , and Al on the PI substrate were well controlled to as low as 0.457, 0.326, and 12.3 nm, respectively. The devices can be arbitrarily curled on the substrate; therefore, the results are expected to facilitate the development of flexible electronic applications with high bending characteristics.

We present the development of conductive nanoporous CNT/chitosan membrane for charge-selective transport of charged molecules, carboxylfluorescein (CF), substance P, and tumor necrosis factor-alpha (TNF-α). The membrane was made porous and conductive via gelatin nanoparticle leaching technique and addition of carbon nanotubes, respectively. These nanoporous membranes discriminate the diffusion of positive-charged molecules while inhibiting the passage of negative-charged molecules as positive potential was applied. The permeation selectivity of these membranes is reversed by converting the polarity of applied potential into negative. Based on this principle, charged molecules (carboxylfluorescein, substance P, and TNF-α) are successfully filtered through these membranes. This system shows 30 times more selective for CF than substance P as positive potential was applied, while 2.5 times more selective for substance P than CF as negative potential was applied.

This paper successfully used inclined exposure technology to fabricate a wafer-level 3D micro cube beam splitter with a 45° optical grade surface (~1.4 mm thick). This research also tests the effect of solvent loss percentage of the SU-8 3035 polymer material (85.45 % solvent removal) to optimum surface roughness on the surface roughness of inclined surfaces. The smallest surface roughness achieved in the experiments using SU-8 3035 material with a thickness of 1.4 mm was less than 34 nm (400 × 400 μm area). And the reflective surface roughness of the molding cube beam-splitter is below 2 nm. The optical power of the fabricated cube beam splitter is about 60.55 and 39.44 % for transmission and reflection, respectively. This type of micro cube beam-splitter can be used as a key component in Pico-projectors, Interferometers, bio detection systems, data storage systems, and linear encoder optic systems. And this novel technology also has the characteristics of high throughput and wafer-level assembly.

Scanning electron microscopy has been developed for topographic analysis at the nanometer scale. Herein, we present a silicon p-n diode with multi-annular configuration to detect backscattering electrons (BSE) in a homemade desktop scanning electron microscope (SEM). The multi-annular configuration enables the enhancement of the topography contrast of 82.11 nA/&mu, m as compared with the commercial multi-fan-shaped BSE detector of 40.08 nA/&mu, m. Additionally, we integrated it with lateral p-n junction processing and aluminum grid structure to increase the sensitivity and efficiency of the multi-annular BSE detector that gives higher sensitivity of atomic number contrast and better surface topography contrast of BSE images for low-energy detection. The responsivity data also shows that MA-AL and MA p-n detectors have higher gain value than the MA detector does. The standard deviation of measurements is no higher than 1%. These results verify that MA p-n and MA-AL detectors are stable and can function well in SEM for low-energy applications. It is demonstrated that the multi-annular (MA) detectors are well suited for imaging in SEM systems.

The purpose of this paper is based on micro fabrication technology, while integrating planar waveguide technology and the scattering phenomenon generated by electro-statically actuator thin film, to develop a 2-dimensional display technology capable of being cleared and re-displayed. For thin film displacement, the restoration of inward elasticity needs to be overcome. During thin film displacement, attraction due to suction occurs when coming into contact with light waveguide; electrostatic force and elastic force are restored and mutually balanced, causing display to light up. On the other hand, when input voltage is released, electrostatic force stops and thin film is restored to original position, causing display to darken. The design structure uses SU-8 as supporting posts, and PDMS as the electrostatic thin film suspended above the glass substrate (light waveguide). The experimental results show that a waveguide with an electrode length of 250 μm (sub-pixel length), a micro-post height of 27 μm, and a PDMS film thickness of 16 μm requires an actuator voltage of 314 V; and a micro-post height of 27 μm, and a PDMS film thickness of 8 μm requires an actuator voltage of 189 V. Thus, with an arrayed micro-electrode design, electronic paper and panels with large color display area could be manufactured.

A novel wettability switchable surface which shields out any interference from driving energy is demonstrated. In this mechanism, a free-standing metal/polymer membrane with hydrophobic microposts is sustained by spacers, and electrostatic force is used to carry out the deflection of the metal/polymer membrane, hence changing the surface morphology as well as the fraction of a liquid/solid interface. Water contact angles under this mechanism can be manipulated from 131° to 152°, depending on the fraction of a liquid/solid interface. Since the driving energy of electrostatic action is shielded out by the ground electrode, the ingredients carried in the droplet can be thoroughly free from the interference and maintain functionality. Therefore, this mechanism has great potential to manipulate microdroplets for digital fluidic systems in bio-applications.Corrections were made to this article on 8 February 2007. The corrections were made to the authors' affiliation details and on page 491 below equations (2) and (3). The corrected electronic version is identical to the print version.

A novel silicon strip detector has been developed that has the necessary properties to provide two-dimensional position sensitivity with a moderate number of readouts and single-sided detector fabrication process. The concept is based on segmented pixel electrodes arranged in a projective X-Y readouts, it combines the 2-D position resolution of pixel electrode geometry with the simplicity of the projective readout of a double-sided strip detector. And also with proper segmentation of strip electrodes, the multi-hits induced ghost image problem can be resolved.

One of the reason caused the production of scar is the excessive sediment or the overtime precipitation during the wounds healing. So far amount all the medical supplies, hydrocolloid dressings which used to repair the burn wounds and the normal trauma are bass on promotion of wound healing. Nevertheless there are no medical supplies combine hydrocolloid dressings with anti-pigmentation drugs; therefor our research has focused on preparing gelatin nanoparticle. First, prepared different size of particles by controlling the parameters. Second, loaded various concentrations of ascorbic acid into particles, analyzed the drug entrapment efficiency and the rate of drug release. Last, co-culture nanoparticle with fibroblast, research the effect of nanoparticle on the fibroblast, in order to prepare a successful anti pigmentation gelatin nanoparticle. Under distinct condition, particle size 150nm ~ 300nm of gelatin nanoparticle could be prepared, furthermore the effective concentration of ascorbic acid 0.3%~10% is successfully completed and the drug-loaded nanoparticles are able to extend the life-span of the fibroblast.

This paper proposes a novel method to fabricate multi-layers, embedded micro fluidic structures by simply employing dosage-controlled UV exposure on thick SU-8 resist and anti-reflection coating on the bottom surface to prevent the reflection UV-light from inducing exposure. Experimental results show the top wall thickness of the embedded micro-channels can be well controlled in a resolution of 2 μm for the UV dosage from 120 to 190 mJ/cm2. Stacked micro-channels have also been successfully realized and showed no interference on the bottom structures when the top structures are being exposed. Numerical simulation of the top wall thickness by UV exposure dosage control has also been conducted, and the comparison between the calculated and experimental results showed similarity in trend. This simple and inexpensive method can be applied to fabricate multi-layers of complex fluidic systems for the applications of μTAS (MicroTotal Analysis System), inkjet printhead, capillary electrophoresis, and micro PCR (Polymerase Chain Reaction).

This paper reports a novel way to compensate the air gap between photomask and photoresist for eliminating UV light diffraction on photoresist, which greatly increases the sidewall straightness of high-aspect-ratio resist structures. In this research, SU-8 negative tone photoresist was used for experiments, and glycerol was employed as an index match material for bridging air gap between photomask and photoresist during exposure. Results showed that a high aspect ratio wall structure of 156 μm thick and 25 μm wide had a 45% pattern width error when exposed under 100 μm air gap, while glycerol compensated process accomplished a straight resist wall without appreciable error. This method is simple and cheap to employ, compared to the usage of costly thick-photoresist-film spinner for resist planarization. Numerical simulation on the diffraction effect upon the structure wall has also been conducted. The calculated and experiment wall profiles showed similarity in trend.

Power and energy consumption are the two most important factors for successful operation; they also play important roles in performance identification. The measurement of power and energy consumption is a common test in the development process of a competition mobile robot. If the power of a competition mobile robot is not sufficient, the running time in the competition will be too long and winning the competition will not be possible. Thus, the power and energy consumption are basic and important measurement parameters for a competition mobile robot. In this paper, five types of hand-made competition mobile robots are successfully developed and their performances are measured. From the measurements, their powers and energy consumptions are evaluated and analyzed, respectively. The test results show large differences in the powers and energy consumptions of the five models, even though the same motors were used. The design and construction of the competition mobile robot are the key parameters that cause these huge differences. It is possible to develop the measurement techniques for power and energy consumption, quickly and precisely, to determine how to modify a competition mobile robot rapidly and efficiently to a condition optimal for a mobile robot competition.

In this study, micro-opto-electro-mechanical systems (MOEMS) technology was used to design an innovative and compact 10 × 6 × 1.5 mm) 3D micro prism, featuring three distinct 45° inclined optical surfaces that simplify the optical design and dimensions of the micro-projection system. The 3D micro-prism manufacturing process is based on a process involving three time inclined exposures and thickfilm (1.5 mm). The roughness of the inclined surface reached 29.8 nm, improving the 407-nm surface roughness yielded by computer numerical control (CNC) processing.

The purpose of this study was to investigate if PPARγplays a role in the melanogenesis. B16/F10 cells were divided into five groups: control, melanin stimulating hormone (α-MSH),α-MSH+retinol,α-MSH+GW9662 (PPARγantagonist), and GW9662. Cells in the control group were cultured in the Dulbecco’s modified Eagle’s medium (DMEM) for 48 hrs. To initiate the melanogenesis, cells in allα-MSH groups were cultured in medium containingα-MSH (10 nM) for 48 hrs. Cells were treated simultaneously with retinol (5 μM) in theα-MSH+retinol group. Instead of retinol, GW9662 (10 μM) was cocultured in theα-MSH+GW9662 group. Cells in the final group were cultured in the DMEM with GW9662. All the analyses were carried out 48 hours after treatments. Theα-MSH was able to increase cell number, melanin production, and the activity of tyrosinase, the limiting enzyme in melanogenesis. Theseα-MSH-induced changes were prevented either by retinol or by GW9662. Further analyses of the activities of antioxidant enzymes including glutathione, catalase, and the superoxide dismutase (SOD) showed thatα-MSH treatment raised the activity of SOD which was dependent on PPARγlevel. According to our results, theα-MSH-induced melanogenesis was PPARγdependent, which also modulated the expression of SOD.

In this article, a nanoporous chitosan polymer membrane was successfully produced and applied as microdialysis membrane forin vitrosampling of biomolecules. With the use of nanoparticle leaching technique, porogenic gelatin nanoparticles formed nanopores in the chitosan-based membrane to create a secure implantable nanoporous membrane for biomolecule sampling. The gelatin nanoparticles size was in the range of 45 to 70 nm, and the pore size of the chitosan membrane was around 40 to 100 nm. The porosity of membrane was found to be dependent on the mixing ratio of chitosan solution and gelatin nanoparticles solution. The results of diffusion study showed that we can alter the mixing ratio of porogen to achieve size-selective molecular diffusion, which means that the porosity and cut-off size of porous membrane can be controlled. The recoveries of the probe fabricated from the chitosan-based membrane were examined for four different model compounds of different molecular weights: 2-NBDG, substance P, TNF-α, and FITC-BSA. The microdialysis probes showed linear responses and substantial recovery to various concentrations of biomolecules. These results indicated that the microdialysis probe constructed by chitosan nanoporous membrane could sample and monitor the biomoleculesin vitroand has the potential for the applicationin vivo.

For a control system, the static performance is always a milestone of dynamic performance of the system. The static performance of the actuator plays an important role due to it affects the dynamic properties quality of a control system and the results of dynamic identification. In order to investigate the dynamic characteristics of the pneumatic actuator of a bionic handling assistant, that the successful development of efficient the self-designed system will be used for the static characteristics measurement of this bionic handling assistant. In this paper, by analysing the output stroke of the pneumatic actuator of bionic handling assistant, the static characteristics of a pneumatic actuator of bionic handling assistant are evaluated. Through measurement of Elongation (E) and Height (H) deformation of the pneumatic actuator of bionic handling assistant in order to figure out the proper operating range, and the right components can be chosen to fit different requirements for an automation system in the future. Furthermore, it can be provided the evaluated data to manufacturing system design. This is the final destination to judge static characteristics.

A novel silicon p-i-n diodes for detecting backscattering electrons in SEM was proposed and fabricated. The multi-annular configuration enables to provide better surface topography contrast of BSE image compared with traditional quadratic configuration. In this study, the multi-annular backscattered electron detector (BSED) can provide surface topography contrast of 82.11 nA/μm, which is 105% increase as compared with commercial BSED. Besides, the multi-annular detector has lower threshold detective energy of 1.28 keV and wide detective dynamic range (up to 30 keV). It is demonstrated that the multi-annular BSE detector is well suited for imaging in SEM system.

This paper describes a Self-Aligned Wet (SAW) cell suitable for direct-cell or bacteria incubation and observation in a wet environment inside a transmission electron microscope. This SAW cell is fabricated by a bulk-micromachining process and composed of two structurally complementary counterparts (an out-frame and an in-frame), where each contain a silicon nitride film based observation window. The in- and out-frames can be self-aligned via a mechanism of surface tension from a bio-sample droplet without the aid of positioning stages. The liquid chamber is enclosed between two silicon nitride membranes that are thin enough to allow high energy electrons to penetrate while also sustaining the pressure difference between the TEM vacuum and the vapor pressure within the liquid chamber. A large field of view (150 μm × 150 μm) in a SAW cell is favored and formed from a larger sized observation window in the out-frame, which is fabricated using a unique circular membrane formation process. In this paper, we introduce a novel design to circumvent the challenges of charging/heating problems in silicon nitride that arise from interactions with an electron beam. This paper also demonstrates TEM observations of D. Radiodurans growth in a liquid environment within a thicker chamber (20 μm) within a SAW cell.

This paper proposes a facile method to fabricate nanoporous microstructures by a photo-patternable SU-8 photoresist, to serve as a molecular filter in microfluidic systems. The fabrication process involves solvent-controlled nanoporous structure formation combined with standard photolithography steps for microstructure fabrication. The self-formed nanoporous morphology embedded inside the microstructure exhibits a sufficient mechanical strength and eliminates complex processes or protocols for integration/assembly of nano- and microstructures. Field emission gun scanning electronic microscopy (FEGSEM) images showed the fabricated nanoporous morphologies with embedded nanogaps of about 6–10 nm. Atomic force microscopy (AFM) images also depicted a clear difference on the degree of porosity between the solvent-controlled SU-8 and the standard resist. Fluorescent dyes, namely Rhodamine-B and Rhodamine-6G, were employed to estimate the diffusivity of the fabricated SU-8 based nanofilter and demonstrated that the Rhodamine based fluorescent molecules can penetrate these nanosized filtration structures. The fabricated nanofilter was capable of providing a molecular weight cut-off range up to 70 kDa, estimated roughly for a molecule with a diameter of 6–10 nm. This simple process provides a novel way to integrate the nanofiltration capability into microstructures while maintaining a sufficient mechanical strength for molecular level filtration in lab-on-chip (LOC) systems.

A method using gold nanoparticles (GNPs) to enhance fiber optic interferometry (GNPFOI) for immune-sensing is reported in this paper. It is suggested that an enlarged index mismatch and an elongated optical path by GNPs conjugated on recognition proteins will contribute most to signal enhancement in the interference fringe shift. Theoretical and experimental results show that the interference fringe shift is linearly related to both the amount and size of the GNPs binding on the sensor surface. The detected signal for 30 nm GNPs can reach a lowest detection limit of 18 pM (10(10) particles ml(-1)). Immune-sensing for rabbit IgG as the antigen to anti-rabbit IgG has been demonstrated and a detection cycle has been completed by elution buffer for surface regeneration. The repeatability of the immune-sensing on one GNPFOI sensor has also been verified by three identical cycles, and the detection limit for 13 nm GNPs conjugated anti-rabbit IgG reaches 0.17 nM (∼25.5 ng ml(-1)). The sensory mechanism has the potential to be engineered on the tip of a needle-type micro-device, which would allow it to monitor immune recognition signals in the future.

This paper successfully used inclined exposure technology to fabricate 50/50 3D micro cube beam splitter with 45° optical grade surface (∼1.4 mm thick). This paper tests the effect of solvent loss percentage of the polymer material (optimum surface roughness: 85.45% solvent remove) on the surface roughness of inclined surfaces. The smallest surface roughness achieved in the experiments using SU-8 material with a thickness of 1.4 mm was less than 70 nm (400μm × 400μm area). This type of micro-mirror can be used as a key component in Michelson Interferometer, bio detection systems, data storage system and linear encoder.

In the present study, we proposed a design of asymmetric planar electrodes for long-term monitoring of glucose level at body temperature. The asymmetric planar electrodes were fabricated by thin film technology on glass and cut as chip sensor. The glass-based chip sensor was further immobilized with glucose oxidase for glucose measuring. To investigate the stability of the glass-based chip sensor, we performed a long-term study and compared with a commercial polymer sensor. All of the experiments were carried out in phosphate buffer solution at 37°C. The result indicated that the glass-based chip senor was more stable in background signal than a commercial polymer sensor during a 18 days of study. The chip senor immobilized with glucose oxidase showed fast response time and broad detection range for glucose measurement. The present study demonstrated that our design of asymmetric planar electrodes was suitable for developing a glucose sensor with long-term stability.

In this work, a novel fabrication process of self-formed polymer nanopillars by reactive ion etching (RIE) is proposed. During this one-step RIE process, polymer nanopillars were generated adjacent XPS surface analysisto glass slide that was partially covered on treated polymer of either PDMS or parylene C. The surface morphologies and water contact angles were compared for different RIE parameters of RF-power and etching time. The aspect-ratio and water contact angle of nanopillar could reach 10 and 162.6deg, respectively. Furthermore, the mechanism of this novel fabrication process was established based on the evidences of nanopillar distribution and XPS surface analysis.

In this study, a novel fabrication method of nanostructure by reactive ion etching (RIE) process on PDMS without predefinition of nanopattern is proposed. During etching process, self-formed high-aspect-ratio nanostructure was observed on PDMS surface adjacent to SiO2 area, suggested the provision of nano masks from the SiO2 residue during RIE etching. In tuning the flow rate of working gases (CF4, O2), the distribution of nanostructure can be controlled. Furthermore, it was observed that different species of nanostructures could be fabricated by the selection of mask materials (SiO2, Cu) under RIE etching.

A novel surface wettability switchable device was successfully demonstrated by changing the surface morphology to induce contact angle change. The surface morphology transformation carried out from the deflection of thin PDMS membrane, driven by electrostatic force, can dynamically change the surface contact angle from 131 ° to 152 ° based on the contact area variation. The electrostatic energy can be throughout shielded out from droplets thanks to ground shielding effect. Since there is no direct physical or chemical (thermal, electrical, UV light etc.) interference from this actuation mean to biological solutions, the proposed method has great potential on microscale droplet transportation and is suitable to many applications especially digital fluidic systems.

A monolithic thermal droplet generator with photopolymer nozzle plate has been developed and demonstrated to operate successfully. The micro droplet generators are realized by direct formation of the nozzles plate, made by SU-8 photoresist, on the top of a silicon wafer with a micro heater array. For the monolithic fabrication, a UV-dosage control and antireflection coating techniques are used to form chambers, manifolds and nozzles. This simpler and more cost-effective fabrication process can lower the fabrication complexity as well as cost, and achieve high alignment accuracy on the nozzle plate to the heater.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Although the stability of the nanobubble remains a controversial issue that is subject to the classical predictions of high Laplace pressure, we demonstrate that a hydrogen nanobubble can be generated and stabilized in an aqueous solution of Keyhole limpet hemocyanin (KLH) protein via an electron radiolysis process. The hydrogen gas inside the nanobubble is in a “dense gas” phase that is characterized by a Knudsen number and number density of hydrogen molecules. The dynamics of nanobubbles are analyzed using time-series electron microscopy images. The growth of small nanobubbles will be affected by the largest neighboring nanobubble; however, a diffusive shielding effect for small nanobubbles is observed. Locally, anti-Ostwald ripening of nanobubbles can be observed; however, the global growth behavior among the nanobubbles is randomly correlated because the characteristic diffusion length of the hydrogen molecules is considerably greater than the average spacing among the nanobubbles.

By integrating a planar waveguide and scattering phenomenon generated by electrostatically actuating a transparent polymer thin film, a display chip capable of being cleared and re-displayed was developed using micro fabrication technology. In the design of the display chip, a freestanding transparent PDMS/ITO conductive composite membrane is sustained by SU-8 spacers above a glass substrate which acts as a light waveguide, and electrostatic force is used to carry out the deflection of the PDMS/ITO composite membrane. When electrostatic force is applied, the PDMS/ITO composite membrane deflects and comes into contact with the glass substrate, causing light to leak out of the waveguide, due to which the critical angle of the total internal reflection of the glass waveguide changes. On switching off the electric potential, the PDMS/ITO membrane returns to its initial state so that light cannot leak out, and a dark spot is formed. Thus, micro-optical switching can be performed by this mechanism. In this display chip an aluminum layer was applied as an adhesive layer between the SU-8 spacers and the glass waveguide, which prevented the leakage of light. The experimental results show that a waveguide with an electrode length of 250 µm (sub-pixel length), a micro-post height of 23 µm and a PDMS film thickness of 8 µm require an actuator voltage of 149 V to operate in a pull-in mode. The optical testing results successfully demonstrate the functionality and the ability to light up multiple pixels of an electrostatic actuating display (EAD) device. Therefore, the EAD device has great potential for the development of low cost dual displays.

A low hysteresis surface prepared by two-length-scaled hierarchical textures to mimic the Lotus effect is proposed. The fabricated textures incorporate self-masked nanorods on microextrusions. A high static contact angle (160°) and low hysteresis (∼2.7°) are obtained and comparable to the surface properties of a natural lotus leaf. The stability of hydrophobicity is described with respect to three energy states (nonwetting, microwetting, and nanowetting) based on dynamic contact angle analysis by droplet impinging onto the surface. The estimated texture-induced energy barrier based on the principle of energy conservation is in good agreement to those estimated from Laplace’s law.