Abstract: A novel 3D discrete T-shaped electrode array, fabricated by PolymMUMPs, is presented for pumping microscale liquid utilizing AC electro-osmosis (ACEO). Both the theoretical and experimental work has been carried out to evaluate the new design concept. A 3D finite element model of a unit cell incorporating a pair of electrodes is created to simulate pump performance. The new design is prototyped using the PolyMUMPs process and the experimental evaluation of its performance is conducted with saline solution at three different voltages. The maximum velocity obtained from the tracing particles at 30μm above the bottom of the channel was 90μm/s, 130μm/s and 200μm/s for a voltage of 6Vpp, 8Vpp and 10Vpp respectively.
Abstract: Cochlear Implant's (CI's) are devices that provides sense of sound to people who are deaf or severely hard of hearing. The important issue with CI's is the electrode design and its placement. The array should be placed close to the modiolar wall of cochlea to stimulate the auditory neurons in accordance with the frequency of the sound and the tonotopic organization of cochlea. It should be flexible for easy surgical insertion and biocompatible enough to withstand the hostile and saline warm environment inside the cochlea. Silicon semiconductor micro-fabrication is an promising technology for advanced CI electrode arrays which will replace the traditional fabrication method. In this paper the design for the silicon electrode array with its consideration is shown. Preliminary simulation results for a stiff probe puncturing the cochlear auditory nerve, which is done to get the stimulation pattern and to realise the mechanical strength of the stiff probe.
Abstract: Individually released polystyrene-platinum bimorph microcantilevers that have potential applications as MEMS/NEMS thermal actuators are produced using focused ion beam micromachining technique. The microcantilevers are sharply defined and triangular in cross-section, and are about 20µm long, 2 µm wide and 1.5 µm thick. The fabrication process is fast (< 3 hours) and does not require any mask or resist. The nanometer-scale displacement of the resulting bimorph microactuator with respect to temperature change is recorded via imaging in a scanning electron microscope, equipped with a heating stage. By increasing the temperature to ca. 55 °C, a tip deflection of ca. 380 nm was measured. This result is compared with the numerical result obtained from a finite element analysis (FEA).
Abstract: With high piezoelectric coefficient (d33> 300 pC/N) and electromechanical coupling factor (kt = 0.45), lead-free barium strontium zirconium titanate ((Ba0.95Sr0.05) (Zr0.05Ti0.95) O3, abbreviated as BSZT)was used to fabricate BSZT/epoxy 1-3 composites with different volume fractions of BSZT ranging from 0.55 - 0.85. The electromechanical properties of the 1-3 composites were determined by the resonance technique. It was found that the theoretical modeling of the 1-3 composites matches quite well with the measured material properties.The 1-3 composite with f = 0.65 was chosen to be fabricated as a transducer due to its comparatively high value of kt. The BSZT/epoxy 1-3 composite transducer demonstrates large bandwidth with good sensitivity, suggesting high potential in biomedical applications.
Abstract: Pressure sensors using MEMS technology have been advanced due to their low cost, small size and high sensitivity, which is an advantage for biomedical applications. In this paper,silicon nanowire was proposed to be used as the piezoresistors due to the high sensitivity .The sensors were designed, and characterized for the use of medical devices for pressure monitoring. The pressure sensor size is 2mm x 2mm with embedded SiNWs of 90nm x150nm been fabricated. Additionally, the sensitivity of 0.0024 Pa-1 pressure sensor has been demonstrated.
Abstract: Capsule endoscopy is a medical procedure to painlessly image the Gastro intestinal tract for the diagnosis of small intestine mucosa. Present capsule endoscopy does not comprise an effective method to localize and tag the abnormalities in gastrointestinal tract during the image diagnosis. The major constraint for developing an addition function to the existing capsule is the limited package space. In this paper, we propose a novel method for the effective localization of site of interest by incorporating a miniaturized tagging module inside the capsule. The tagging module release a micro tag which embed into the region of interest upon activation. This micro tag can be detected through radiographic imaging techniques like X-ray imaging. Embedded micro tag provides valuable position information of the site of interest to facilitate further diagnosis. This paper will present the ex-vivo animal trials and the x-ray imaging result of the tagging module.
Abstract: Traveling light is totally reflected on boundary, the evanescent wave intensity exhibits exponential decay with distance from the boundary at which the wave was formed. In this paper, we do theoretical analysis of the total reflected light phase shift and power value of the evanescent wave was “disturbed” by the other objects. A marvelous optics phenomenon is the -π/2 phase shift of reflected light.
Abstract: This paper reports a process of filling and planarization of microstructures for MEMS and wafer level packaging application. In this work, cavities of 5-10mm depth and 20-100mm in length/width are filled using multiple coatings of polyimide with kinematic viscosities in the range of 20-130St. Such filling results in overfilling of polyimide in the range of 2 to 10mm due to variation in density and geometry of microstructure. A chemical and mechanical polishing (CMP) based planarization process, to achieve polyimide thickness variation <0.2mm in varied structures is presented.
Abstract: Under mild conditions, trihydridosilanes interact with a variety of clean, hydrogenated and fresh metal and metalloid surfaces, including titanium, silicon and gold. In contrast, monohydridosilanes appear to have minimal interaction. All classes of hydridosilanes have minimal interaction with anhydrous oxide surfaces. Preliminary results suggest that surface modification with trihydridosilanes may provide a route for generating self-assembled monolayers on metal substrates. The synthesis of new trihydridosilanes is described. Contact angle, FTIR and XPS data for modified surfaces are provided.
Abstract: An electrothermally actuated planar micromotor has been developed for multi degree-of-freedom (DoF) motion, including rolling along the vertical or horizontal axes, spinning about the z-axis, and also the out-of-plane piston motion. In this design, a light-weight spherical solder ball rotor with plastic core is supported by electrothermal actuator array (EAA). Each bimorph actuator consists of the silicon and aluminum layers to produce large vertical deflection due to their distinct coefficients of thermal expansion (CTE). The micromotor fabrication procedures involve standard CMOS-MEMS processes. Rolling and spinning motions of the spherical rotor are performed by driving the electrothermal actuators with multi-phase signals, and the piston motion can be achieved by synchronizing the drive signals to all actuators without phase difference. The dynamic behavior of this micromotor has been successfully predicted by multibody dynamics simulation software. Such unique dynamic motions of this planar micromotor device show promising capabilities in Optical Coherence Tomography (OCT) and Optical Coherence Microscope (OCM) applications. If this sphere is mounted with a highly-reflective mirror platform, it can be used to divert the light beam to achieve a full 360° circumferential scan about the optical axis.