Aerodynamic Evaluation of Flapping Wings with Leading-Edge Twisting.

The purpose of the current study is to emphasize the characteristics and phenomena of leading-edge twisting in flapping wing vehicles. A fused deposition modeling (FDM) 3D printing method is applied to develop the flapping mechanisms with bevel gears to achieve the leading-edge twisting. Three flapping mechanisms were developed, including simple flapping only (type-A1: normal servo mechanism), flapping with continuous leading-edge twisting (type-B: servo-bevel gear mechanism), and flapping with restricted leading-edge twisting via mechanical stoppers (type-B1: servo-bevel gear mechanism with adjustable mechanical stoppers). Utilizing a low-speed wind tunnel, the aerodynamic performances of these mechanisms are examined by extracting their lift and net thrust forces. The wind tunnel testing data showed that the flapping with restricted leading-edge twisting via mechanical stoppers (type-B1) showed better performance than the simple flapping (type-A1) by 32.9%, and also better performance than the flapping with continuous leading-edge twisting (type-B) by 64%. Next, MATLAB software was used to create the 3D wing surfaces from the instantaneous stereophotography Kwon3D trajectories to fully sketch the leading-edge twisting features. The 2D airfoil cut sections at the mean aerodynamic chord at different stroke moments depict the instantaneous angles of attack to justify the aforementioned wind tunnel testing data and it was verified using a theoretical trajectory model. This comprehensive study using the 3D-printed mechanisms is well suited for the quantitative evaluation of the lift contribution from leading-edge twisting.

Application of Flexible Four-In-One Microsensor to Internal Real-Time Monitoring of Proton Exchange Membrane Fuel Cell.

In recent years, the development of green energy sources, such as fuel cell, biomass energy, solar energy, and tidal energy, has become a popular research subject. This study aims at a flexible four-in-one microsensor, which can be embedded in the proton exchange membrane fuel cell (PEMFC) for real-time microscopic diagnosis so as to assist in developing and improving the technology of the fuel cell. Therefore, this study uses micro-electro-mechanical systems (MEMS) technology to integrate a micro humidity sensor, micro pH sensor, micro temperature sensor, and micro voltage sensor into a flexible four-in-one microsensor. This flexible four-in-one microsensor has four functions and is favorably characterized by small size, good acid resistance and temperature resistance, quick response, and real-time measurement. The goal was to be able to put the four-in-one microsensor in any place for measurement without affecting the performance of the fuel cell.

The micro patterning of glutaraldehyde (GA)-crosslinked gelatin and its application to cell-culture.

This paper proposes a novel technique for fabricating micro patterns of glutaraldehyde (GA)-crosslinked gelatin. It provides another means to crosslink gelatin other than using photo-sensitizing agents, and the micro patterns of GA-crosslinked gelatin can still be made successfully by accessing conventional photolithography. A much less toxic and increased biocompatible approach to strengthening the gelatin microstructures can be developed according to this idea. This paper also describes a potential methodology for using GA-crosslinked gelatin patterns as single-cell culture bases. The best spatial resolution of the micro gelatin bases can reach 10 microm, and the selective growing density of human Mesenchymal stem cells on the gelatin patterns surpasses the density on the glass substrate by 2-3 orders of magnitude.

An implantable multifunctional needle type biosensor with integrated RF capability.

We report the development of an implantable multifunctional (glucose and cholesterol) needle type biosensor with integrated RF wireless circuitry for continuous in vivo monitoring of metabolites during short term stays in emergency room or intensive care unit. Silicon-based MEMS technologies are used for the fabrication of micro needle sensors. The whole device is covered by a biocompatible Parylene layer with opening structure at the active areas of electrodes. Electropolymerization of active biomolecules and conducting polymer provides in situ nanoscale physical entrapments of various oxidoreductases (Glucose oxidase and cholesterol oxidase) and functions as a viable matrix for the construction of micro amperometric biosensors. Hybrid CMOS fabrication processes are used to accomplish the 433 MHz ASK RF transmitter and receiver (0.18μm CMOS 1P6M process) and the data converter (0.35μm CMOS 2P4M process). We will present and discuss the detail design and the integrated system performance in this paper.