Showing papers by "Alexander Mamishev published in 2008"

Design of an RFID-Based Battery-Free Programmable Sensing Platform

Abstract: This paper presents the wireless identification and sensing platform (WISP), which is a programmable battery-free sensing and computational platform designed to explore sensor-enhanced radio frequency identification (RFID) applications. WISP uses a 16-bit ultralow-power microcontroller to perform sensing and computation while exclusively operating from harvested RF energy. Sensors that have successfully been integrated into the WISP platform to date include temperature, ambient light, rectified voltage, and orientation. The microcontroller encodes measurements into an electronic product code (EPC) Class 1 Generation 1 compliant ID and dynamically computes the required 16-bit cyclical redundancy checking (CRC). Finally, WISP emulates the EPC protocol to communicate the ID to the RFID reader. To the authors' knowledge, WISP is the first fully programmable computing platform that can operate using power transmitted from a long-range (UHF) RFID reader and communicate arbitrary multibit data in a single response packet.

CFD analysis of electrostatic fluid accelerators for forced convection cooling

Abstract: Classic thermal management solutions for microelectronics are becoming inadequate and there is an increasing need for fundamentally new approaches. Electrohydrodynamic ionic wind pumps, also known as electrostatic fluid accelerators (EFA), have the potential for becoming a critical element in electronics thermal management solutions. As the EFA field continues to evolve, developing new EFA-based technologies will require accurate models that can help predict pump performance metrics, such as air velocity profile, back pressure, and cooling effectiveness. Many previous modeling efforts only account for electrostatic interactions. For truly accurate modeling, however, it is important to include effects of fluid dynamics and space charge diffusion in charge transport. The modeling problem becomes especially challenging for the design and optimization of EFA devices with greater complexity and smaller dimensions. This paper presents a coupled physics finite element model (FEM) using a complete EFA charge transport model including charge diffusion and fluid dynamic effects. A cantilever EFA structure is modeled and analyzed for forced convection cooling. Numerical modeling predicts maximum air velocities of approximately 4 m/s and a maximum convection heat transfer coefficient of 280 W/(m2K) for the cantilever EFA structure investigated. Preliminary experimental results for a microfabricated cantilever EFA device for forced convection cooling are also discussed.

Heat Transfer Enhancement Measurement for Microfabricated Electrostatic Fluid Accelerators

Abstract: Air cooling, because of its simplicity, remains as the most popular cooling solution for microelectronics in the consumer market. However, the trend of increasing heat generation in microelectronics and the demand for compact devices result in heat fluxes approaching the limit of conventional rotary fan air cooling technology. Electrostatic fluid accelerators (EFAs), also known as electrohydrodynamic (EHD) ionic wind pumps, have the potential of becoming a critical element of electronic thermal management solutions. In this technique, application of voltage to a sharp electrode ionizes air molecules, which are propelled by the electric field, transferring part of their energy to neutral air molecules, thus creating airflow and cooling. The airflow, so called ";corona wind";, can be used discretely for hot spot cooling or integrated into a compact thermal exchange surface to decrease the fluid boundary layer and increase heat transfer enhancement. The EFA investigated in this study consists of a microfabricated AFM-cantilever corona electrode using combination of deep reactive ion etching (DRIE) and reactive ion etching (RIE), and a flat collecting electrode that doubles as the thermal exchange surface. The fabrication and testing results of a microfabricated EFA are presented in paper. Free and EFA-enhanced forced convection heat transfers are both reported by measuring the heating power difference of the collecting electrode under constant surface temperature.