Design, simulation, fabrication and testing of microprobes for a new MEMS wafer probe card

A new type of MEMS cantilever wafer probe card consists of an array of microcantilevers individually actuated by bimorph heating to make contact with the test chip was designed and fabricated. This probe card is called the CHIPP (Conformable, High-Pin count, Programmable ) card and can be designed to contact up to 800 I/O pads along the perimeter of a 1 cm2 chip with a microprobe repeat distance of ~50 µm. Each microcantilever had an internal heater and a separate electrode carrying the signal under test and contained four separate layers plus a fifth material for the contact tip region. Different versions of micro-actuators have been designed and made in this Ph.D. research. Ohmic contacts were made with the lowest contact resistance of 250 mΩ. The deflection efficiency varied from 5.23 to 9.6 µm/mW for cantilever length from 300-500 µm. The maximum reversible deflection was in the range of 270 µm. Video recordings made inside the SEM clearly show that ohmic contact was made to a stationery tungsten electrode. A full dynamic deflection (180 µm) for a 50 x 500 µm cantilever occurred in response to input frequency up to nearly 50 Hz. The motion was damped at higher frequencies, with a strong resonance (for a 50 x 500 µm device) at 8160 Hz. Heat loss for devices operating in air was found to be substantially higher than for vacuum operation with a heat loss ratio of about 2/1 for a heater inside the structure; and 4.25/1 for a structure with the heater as an outer layer of the cantilever

Explore the physical and chemical properties of 1,2,3-triazole: from fluorescence sensor to ligand in metal catalysis

1,2,3-Triazole gold (TA--Au) catalysts were developed by Shi\u27s group and employed in several transformations involving propargyl ester rearrangement. Besides the excellent air, moisture and thermal stability introduced through triazole ligands, unique chemoselectivity was observed for these novel Au(I) complexes. The chemoselectivity allowed the effective activation of the alkyne without affecting the reactivity of the allene ester intermediates. These results led to the investigation of the preparation of allene ester intermediates with TA--Au catalysts under anhydrous conditions. As expected, the desired 3,3-rearrangement products were obtained in excellent yields. Besides the typical ester migrating groups, carbonates and carbamates were also found to be suitable for this transformation, which provided a highly efficient, practical method for the preparation of substituted allenes.;Previously research results confirmed TA-Au as a chemoselective catalyst in promoting alkyne activation with high efficiency and improved ligand economy. TA-Au analogues were sequentially revealed as the effective catalysts in promoting allene hydration, giving the enones with excellent yields. Furthermore, the gold-catalyzed intermolecular [2+2] cycloaddition of propargyl esters was achieved with good stereoselectivity. The \u27silver-free\u27 condition was critical for this transformation, while only a trace amount of [2+2] products were obtained in the presence of silver under otherwise identical conditions.;Additionally, naphthalene-bridged bis-triazole (NBT) compounds were prepared and characterized for investigation of their photophysical properties. Unlike our previously reported N-2-aryl triazoles (NATs), which gave strong emissions through the planar intramolecular charge transfer mechanism (PICT), this newly developed NBTs adopted a noncoplanar conformation between triazole and naphthalene, achieving fluorescence through twisted intramolecular charge transfer (TICT)

Power Management for Cloud-Scale Data Centers

Recent years have seen the rapid growth of large and geographically distributed data centers deployed by Internet service operators to support various services such as cloud computing. Consequently, high electricity bills, as well as negative environmental implications (e.g., CO2 emission and global warming) come along. In this thesis, we first propose a novel electricity bill capping algorithm that not only minimizes the electricity cost, but also enforces a cost budget on the monthly bill for cloud-scale data centers that impact the power markets. Our solution first explicitly models the impacts of the power demands induced by cloud-scale data centers on electricity prices and the power consumption of cooling and networking in the minimization of electricity bill. In the second step, if the electricity cost exceeds a desired monthly budget due to unexpectedly high workloads, our solution guarantees the quality of service for premium customers and trades off the request throughput of ordinary customers. We formulate electricity bill capping as two related constrained optimization problems and propose efficient algorithms based on mixed integer programming. We then propose GreenWare, a novel middleware system that conducts dynamic request dispatching to maximize the percentage of renewable energy used to power a network of distributed data centers, subject to the desired cost budget of the Internet service operator. Our solution first explicitly models the intermittent generation of renewable energy, e.g., wind power and solar power, with respect to varying weather conditions in the geographical location of each data center. We then formulate the core objective of GreenWare as a constrained I optimization problem and propose an efficient request dispatching algorithm based on linear-fractional programming (LFP)