Experimental Mechanics in Nano and Biotechnology

Abstract: The fiber optic sensor measuring system based on the Mech-Zehnder interferometry is developed in the paper. The system can be used for the strain and vibration measurement of engineering structure, and has the advantages: convenient adjusting, stable performance and strong ability of anti-interference, etc. Therefore the fiber optic sensor has been widely used in the engineering field. First the system is introduced into measuring the frequency and amplitude of the vibration subjected to force of the FRP-concrete beam. The fiber optic sensor measuring system and the electronic measuring system are synchronous used for the measurement. The analysis results of fiber optic sensor measurement approximate to the results of electronic strain gauge. Then the system is introduced into experimental stress analysis on the gas pipe, good results is obtained too. The paper provides new technical equipment for the experimental testing of various engineering structure using fiber optic sensor, also establishes the technical foundation of the research of smart structure.

Abstract: We designed a new module of Laser Doppler Anemometry (LDA) with fiber optical system, which is mainly comprised of a laser diode, optical fibers and a two dimensional (2D) photodetector. The fiber optical system involved a laser diode (VCSEL, Copax Inc.) with 850 nm wavelength, single mode fiber (Prime Optical Fiber Inc.), half coupler and two fiber collimators. The 2D photodetector made by silicon PIN photodiode is aligned between the two collimators with 39° beams cross angle and all the components were set into a rectangle case, which have coin’s size and can be accommodated by two same set of these components. We added anticoagulant and antiseptic into fresh chicken blood and diluted it with normal saline, and then put the diluted blood into a beaker with a motor in the liquid. The diluted blood was pumped by the motor into an aqueduct which is connected to glass aqueduct, and back to the beaker to form a circulation system. In the experiments, we evaluate the relationships among the blood cell velocity and diameter of glass tube, temperature variation of blood, and concentrations of blood. By analyzing the results of these experiments, the main factor that affects the precision of velocity measurement is the cross angle of two injected laser beams and the intensity of scattering light. The module constructed by optical fiber light can precisely measure the velocity of blood flow at most 5% error.

Abstract: We present a novel microcantilever device with nano-interdigitated electrodes (nano-IDEs) and selective functionalization of nano-IDEs for biosensing applications. The nano-IDEs play a role in precisely addressing capture molecules to a specific region on a microcantilever. This leads to a detectable surface stress due to the binding of target molecules. 70~500 nm-wide gold (Au) nano- IDEs are fabricated on a low-stress SiNx microcantilever with dimensions of 100~600 μm in length, and 15~60 μm in width, with a 0.5 μm thickness using electron beam lithography and bulk micromachining. 32~96 nm-thick streptavidin is selectively deposited on one side of nano-IDEs using cyclic voltammetry at a scan rate of 0.1 V/s with a range of -0.2~0.7 V during 1~5 cycles. The selective deposition of streptavidin is confirmed by fluorescence microscopy and atomic force microscopy (AFM).

Abstract: The conducting polymer PAni is coated on Au electrode sample by spin coater on 500rpm and 3000rpm for 5sec and 30sec. Then, it was drying 10min at 180
C. The layer thickness was 140~200nm. The electrodes were fabricated the resist pattern by electron beam writing machine which was performed on a Raith75 e-Line on the PMMA 950K, thickness 100nm. The electrodes were written at an electron does of 200uAs/cm2 and developed for 40sec in a 1:3 MIBK (methyl-isobutyl-ketone): IPA (isopropyl alcohol) solution. Metal lift-off of the PMMA in acetone was preceded by an e-beam evaporation consisting of 50Å Cr and 250Å Au. Electrical measurements were performed on low-noise commercial probe stations equipped. We measured distance between the electrodes ranges from a few tens of nanometer to hundreds nanometer by AFM (Atomic Force Microscopy) which was done with silicon tips in non-contact mode on a PSIA, XE-100.

Abstract: In this paper, We presents experimental results that demonstrate the pH sensing capability of MW-CNTs. High-density, well-aligned carbon nanotubes, which are MW-CNTs and vertically aligned on a large area of substrate, has been synthesized. The absorption of different range of pH buffer solution in the MW-CNTs changes the conductivity of the MW-CNTs at room temperature. A MEMS-based fabrication process was developed to fabricate a device where MWCNTs based sensing material was precisely assembled pattern.

Abstract: In this paper, an electrical signal detection system for microbiochips is proposed to overcome the limitations of conventional optical systems such as bulky system size and high manufacturing cost. An electrical detection system with interdigitated microelectrodes is fabricated using MEMS technology. High conductive nano size gold particles were selected for the system to detect biological reactions between bio materials in the microbiochip. Experiments were performed with variations of particle densities and electrode gaps. In addition, a simulation to predict the electrical resistance of the microbiochip was developed. Both the simulation and experimental data show that the conductivity increases as the gap becomes narrower and the particle density higher.

Abstract: Electro-Active Paper (EAPap) is attractive for a biomimetic actuator material due to its merits in terms of lightweight, dry condition, large displacement output, low actuation voltage and biodegradability. However, the performance of EAPap actuator is so sensitive to humidity that high humidity is required. We report a robust EAPap actuator that can be activated in room humidity condition. The EAPap is made by dissolving cellulose fibers into a solution using DMAc solvents, and made into a sheet by using casting. Thin electrodes are deposited on the cellulose paper to comprise an EAPap actuator. The fabrication process and the performance evaluation of EAPap are presented in terms of free displacement with respect to frequency and actuation voltage.

Abstract: Utilizing suspended gate field-effect transistors (SGFETs), a displacement sensing mechanism is proposed in this paper. The design, numerical simulations, and fabrication process of the SGFET are presented. The SGFET arrays and the comb-drive actuator are integrated to form a MEMS position encoder. The resolution of the proposed MEMS position encoder is 6 μm over a 54 μm travel range. By arranging the SGFETs into arrays, position feedback over a large travel range is achieved for a comb-drive actuator.

Abstract: A new thermal bimorph actuator for large out-of-plane displacement is designed, fabricated and tested. The deflecting beam is composed of polyimide, heater, and polyvinyl difluorides with tetrafluoroethylene (PVDF-TrFE). The large difference of coefficient of thermal expansion (CTE) of two polymer layers (polyimide and PVDF-TrFE) can generate a large deflection with relatively small temperature rising. Compared to the most conventional micro actuators based on MEMS (micro-electro mechanical system) technology, a large displacement, over 1 mm at 20 mW, could be achieved. The proposed actuator can find applications where a large vertical displacement is needed while keeping compact overall device size, such as a micro zooming lens, micro mirror, micro valve and optical application.

Abstract: This paper presents a new design of an artificial muscle actuator called tube-spring actuator (TSA) that is fabricated with dielectric elastomer. The new actuator construction includes two steps: the first is that a cylindrical actuator is manufactured with dielectric elastomer with multi-layer lamination process. Then a compressed spring is inserted to inside the tube as the second step of the process. The inner spring is used to maximize the axial deformation while constraining the radial contraction. This design enables effective linear actuation with largest amount strain. The monitored strain of active length is up to 15 percents. The manufactured actuator is applied to a robot hand as an example of the actual application.