Yu-Ching Lin

Magnetically modified PDMS microtools for micro particle manipulation

In this paper we describe novel magnetically driven polymeric microtool for non-intrusive and no contamination experiments on a chip. The composite is formed by suspending magnetite particles (Fe3O4) in polydimethylsiloxane (PDMS). In order to obtain precise and complicated pattern of micromagnetic tools, a photolithography techniques has been applied by making good use of thick KMPR-1050 photoresist as sacrificed mould. The surface of the produced micromagnetic tools is specially coated in order to suppress stiction in the biochip. The novelties of these tools are (1) fabrication of any 2D shape, (2) softness (harmless to cells), (3) no contact actuation (no stiction), 4. mass production with low cost. Here we have demonstrated that the mass-produced versatile micromagnetic tools such as stirrer and valve. The potential impact of this technology includes sample selection and separation, cell immobilization, genetic operation, tracking, mixing and reaction techniques into portable microfluidic labs-on-a-chip, culture systems and cell loading system.

On-Chip Micro-Pseudocapacitors for Ultrahigh Energy and Power Delivery

Microscale supercapapcitors based on hierarchical nanoporous hybrid electrodes consisting of 3D bicontinuous nanoporous gold and pseudocapacitive manganese oxide deliver an excellent stack capacitance of 99.1 F cm−3 and a high energy density of 12.7 mW h cm−3 with a retained high power density of 46.6 W cm−3.

Development and evaluation of AuSi eutectic wafer bonding

In this paper, wafer-to-wafer AuSi eutectic bonding was investigated and evaluated with various sets of experimental parameters. Single crystalline Si and amorphous Si were bonded with different dimension Au layers and observed by optical measurements. Material composition, adhesion layer, electrical insulation, bonding parameters, and surface pre-treatments were discussed and have improved bonding performance. Bond strength determined by micro-chevron-test and shear test was evaluated as well as hermeticity. High bond yield was achieved with 4 inch and 6 inch wafer stacks.

On-chip Temperature Sensing and Control for Cell Immobilization

In this study, a temperature sensing and controlling microfluid chip has been developed for cell immobilization using a thermo-sensitive hydrogel (PNIPAAm). The PDMS-based micromagnetic stirrers make microscale fluid mixing to provide the temperature stability in the microchannel. The ITO (indium tin oxide) microheaters and thermosensors, fabricated by micromachining technology, perform in situ fluid heating and feedback temperature control. All temperature sensing and controlling devices are integrated on a chip, in which yeast cell immobilization is performed by the gelation of the PNIPAAm solution.

Scanning probe microscopy with quartz crystal cantilever

This paper reports a quartz crystal cantilever for piezoelectric vibration sensing in scanning probe microscopy (SPM). SPM imaging by a frequency modulation detection method is demonstrated in ambient atmosphere using a 22.5-μm-thick cantilevered AT-cut quartz crystal with metal electrodes on both sides. The spring constant of the cantilever is calculated to be 10N∕m. Despite the low electromechanical coupling between the piezoelectric effect and the flexural vibration, a high sensitivity of 0.07nm∕(Hz)0.5 to vibration is achieved in the second flexural mode. The cantilever self-oscillates on the basis of piezoelectric detection, and offers short-term stability of within approximately 0.5Hz in ambient atmosphere at room temperature. The force curve of the self-oscillating cantilever shows that the self-oscillation can be sustained even when in contact with a sample.

Development of the Large Scanning Mirror Using Fe-Based Metallic Glass Ribbon

In order to achieve the large scanning angle without mechanical failure during actuation, the micro-mirror structure was fabricated using Fe-based metallic glass (MG) ribbon. High values of mechanical strength and elastic strain limit are desired for the torsion bar for providing high performance of the mirror, including large tilting angle and good stability. MG materials guarantee superior value of elastic strain limit and fracture toughness resulting from its amorphous structure without line defects like dislocations and grain boundaries. We chose Fe-base MG material for mirror actuation according to its good soft magnetic properties and simple structure without any further step of integration of magnetic material. Millimeter-size mirror device was successfully fabricated by laser machining techniques from Fe-based MG ribbon. Extremely large optical tilting angle of exceeding 100° was obtained on activation of the mirror by magnetic force when electrical current of 100 mA was applied. Large tilting angle of the mirror is due to the torsion bar which was fabricated with Fe-based MG material that has large elastic strain limit and high fracture toughness.

Focusing and waveguiding of Lamb waves in micro-fabricated piezoelectric phononic plates

This paper presents results on the numerical and experimental studies of focusing and waveguiding of the lowest anti-symmetric Lamb wave in micro-fabricated piezoelectric phononic plates. The phononic structure was based on an AT-cut quartz plate and consisted of a gradient-index phononic crystal (GRIN PC) lens and a linear phononic plate waveguide. The band structures of the square-latticed AT-cut quartz phononic crystal plates with different filling ratios were analyzed using the finite element method. The design of a GRIN PC plate lens which is attached with a linear phononic plate waveguide is proposed. In designing the waveguide, propagation modes in square-latticed PC plates with different waveguide widths were studied and the results were served for the experimental design. In the micro-fabrication, deep reactive ion etching (Deep-RIE) process with a laboratory-made etcher was utilized to fabricate both the GRIN PC plate lens and the linear phononic waveguide on an 80 μm thick AT-cut quartz plate. Interdigital transducers were fabricated directly on the quartz plate to generate the lowest anti-symmetric Lamb waves. A vibro-meter was used to detect the wave fields and the measured results on the focusing and waveguiding of the piezoelectric GRIN PC lens and waveguide are in good accordance with the numerical predictions. The results of this study may serve as a basis for developing an active micro plate lens and related devices.

Design and fabrication of a phononic-crystal-based Love wave resonator in GHz range

This paper presents a method for designing and fabricating a Love wave resonator utilizing the phononic crystal (PC) as the reflectors. The PCs were formed by depositing 2D, periodically etched silica film on a quartz substrate. We analyzed the PC structure, and within its partial bandgap we designed a one-port resonator that contained a set of inter-digital transducer (IDT) inside the resonant cavity bonded by two PC arrays. With sub-micrometer structures, the resonator was designed to operate at 1.25 GHz. The device was fabricated by employing the microelectromechanical system (MEMS) fabrication technology and the resonant performance was evaluated.

Design and fabrication of an AT-cut quartz phononic Lamb wave resonator

This paper presents results on the design and fabrication of an AT-cut quartz Lamb wave resonator with phononic crystal (PC) reflective gratings. The deep reactive ion etching process with a laboratory-made etcher was utilized to fabricate PC structures of the AT-cut quartz Lamb wave resonator. The finite element method was adopted to calculate the PC band structure, effective reflective distance from the PC boundary and further the resonant modes and admittance of the phononic Lamb wave resonant cavity. Through the comparison studies between the experimental and simulated results, a design process for the AT-cut quartz phononic Lamb wave resonator was proposed. It is noted that by using the phononic reflectors, the size of the Lamb wave resonator can be reduced significantly.

Micromirror with large-tilting angle using Fe-based metallic glass

For enhancing the micromirror properties like tilting angle and stability during actuation, Fe-based metallic glass (MG) was applied for torsion bar material. A micromirror with mirror-plate diameter of 900u2009μm and torsion bar dimensions length 250u2009μm, width 30u2009μm and thickness 2.5u2009μm was chosen for the tilting angle tests, which were performed by permanent magnets and electromagnet setup. An extremely large tilting angle of over -270° was obtained from an activation test by permanent magnet that has approximately 0.2u2009T of magnetic strength. A large mechanical tilting angle of over -70° was obtained by applying approximately 1.1u2009mT to the mirror when 93u2009mAwas applied to solenoid setup. The large-tilting angle of the micromirror is due to the torsion bar, which was fabricated with Fe-based MG thin film that has large elastic strain limit, fracture toughness, and excellent magnetic property.