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We report on results of fabrication and characterization of a conductive gel based pressure sensor which can be easily integrated into the commonly used microfluidic devices. The gel elements of the sensor are obtained by casting a viscous mixture of polydimethylsiloxane (PDMS) and metal powders on a patterned template. After solidification, the gel becomes conductive, showing piezoresistive effects that can be used for low pressure sensing. Our fabrication process of the gel elements is fully compatible to the integration requirement of multi-functional PDMS devices and the fabricated pressure sensors can be repeatedly used with direct current readout.

Optical properties of GaN-based light emission diode (LED) cooled with microfluidics have been studied as a function of injection currents at different water flow rates. Without cooling, the quantum efficiency of the LED emission degrades for large injection currents because of the limited heat dissipation. With microfluidic cooling, the maximum achievable injection current and the maximum light emission intensity increase with the water flow rate. Correspondingly, the red-shifts of the emission peaks are reduced in the whole range of the injection currents when the LED is cooled. Such a simple technique should also be applicable to other types of LEDs or high density LED arrays.

This paper discusses a membraneless microfluidic fuel cell using the multi-stream laminar flow to keep the fuel and oxidant streams separated when they are flowing at a low Reynolds number state. The system we used consists of a microfluidic channel with three inlets. The fuel, oxidant, and the electrolyte solution enter the channel from the inlets and continue to flow in parallel without turbulent mixing (diffusive exchange occurs across the interface at a micro scale). During the working process of the fuel cell, controllable output potential and current of the fuel cell can be obtained and studied by changing the flow rate of the stream between the fuel and the oxidant. Results indicate that this novel design can be used in microscopic scale power source systems such as the lab-on-chip control systems because it is easy to integrate with other micro functional systems.

Pre-amorphization implantation has been applied as a shallow junction technology. Roughness at amorphous/crystalline (a/c) interface should be controlled to improve junction characteristics. To understand and model a/c interface roughness, molecular dynamic method is applied in simulating pre-amorphization implantation. A method to reproduce roughness at a/c interface by molecular dynamic simulation is presented. A model of interface roughness is presented. Si and Ge implantation from 2-20keV at a dose of 1x10^1^5cm^-^2 is simulated. The depth of a/c interface is reproduced. Experimental results of a/c interface roughness are successfully simulated. The interface roughness is well reproduced and interpreted by the model presented.