Quanbo Zou

Miniaturized independently controllable multichamber thermal cycler

This paper presents the design, fabrication, and characterization of a miniaturized multichamber thermal cycler that is independently controllable with multiplex thermal protocols for the polymerase chain reaction (PCR) of nucleic acids. Thermal isolation between multiple chambers is achieved by an etch-through slot on a silicon membrane containing the reaction chambers, while keeping the silicon substrate unheated by directly contacting the substrate with a bottom heat sink. The thermal response is very fast due to reduced parasitic thermal mass. Typical ramping and cooling rates achieved are 15-100/spl deg/C/s and 10-70/spl deg/C/s, respectively. In contrast to uniform heating, as reported by other research groups, a side-heating scheme is used in this study to improve the temperature uniformity inside the reaction chamber. Finite-element-analysis (FEA) is used to predict and optimize the thermal performance. A temperature uniformity of </spl plusmn/ 0.15/spl deg/C in the reaction chamber filled up with water has been measured at 95/spl deg/C, while keeping the substrate temperature as low as 0.4/spl deg/C above the room temperature. This ensures independent controllability of multichamber thermal multiplexing on the same chip with low thermal cross talk between chambers. Experiments are in agreement with FEA predictions. The developed device can be used for quick optimization of PCR protocols and multiplexing of numbers of PCR reactions simultaneously in a short time.

A study on micromachined bimetallic actuation

Abstract This paper presents a theoretical and experimental study of bimetallic actuation in micro-electro-mechanical systems (MEMS). The finite element method (FEM) has been used to predict and optimize the performance of bimetallic membranes, including maximum deflection, actuation force under definite temperature load, and their natural frequencies with fluidic (air or liquid) damping. The study involves micromachined pumps, valves and some other structures. Heat transfer analysis is also conducted to evaluate the temperature field distribution and the transient behavior of the microstructures. Some structures have been obtained for high displacements under low driving power, and also for quick response of bimetallic pumps. The results show that the experiments agree well with theoretical predictions.

LOW COST MICRO-PCR ARRAY AND MICRO-FLUIDIC INTEGRATION ON SINGLE SILICON CHIP

In this paper, a 2×2 micro-PCR array and integrated micro-fluidics in single silicon wafer are reported. The fastest thermal response in literature has been achieved in this device. Single wafer process for the device fabrication is developed for low cost. DRIE is used to form the reaction chamber. The chamber is sealed by a dielectric membrane, which is transparent to fluorescence signal for detection. The chamber is isolated from substrate by trenches. Heater and sensor are integrated on side of the chamber based on a unique joint heating concept. Temperature uniformity is less than 0.2°C. Cross talk is less than 0.5%. Thermal cycling can be finished within 2 minutes for 30 cycles (cycling point: 55°C, 72°C and 95°C). Other fluidic components (pump and valve) can be integrated in the same chip easily. Fluorescence detection of DNA is used to verify the devices before and after PCR reaction.

FLIP-CHIP PACKAGED MICRO-PLATE FOR LOW COST THERMAL MULTIPLEXING

In this work, a low cost micro-plate array is developed using flip-chip technique for thermal multiplexing. The microplate is made of silicon chip with on-chip heater and temperature sensor for accurate control of temperature. These silicon chips are flip-chip bonded on a printed-circuit-board (PCB) and arranged in array for thermal multiplexing. By proper thermal design, high performance of thermal cycling has been achieved in this work. The micro-plate array has been used with a plastic chip together as multichamber micro-polymerase chain reaction (uPCR), which can perform independent protocol in each chamber simultaneously.