C G J Schabmueller

Self-aligning gas/liquid micropump

In this paper a piezoelectrically driven silicon membrane pump with passive dynamic valves is described. It is designed to pump gases and liquids and to be tolerant to gas bubbles. Reducing the dead volume within the pump, and thus increasing the compression ratio, one achieves the gas pumping. The main advantages and novel features of the pump described in the paper are the self-aligning of the membrane unit to the valve unit and the possibility of using screen-printed PZT as actuator, which enables mass production and thus low-cost micropumps. A liquid pump rate of 1500 μl min−1 and a gas pump rate of 690 μl min−1 were achieved.

Micromachined chemical reaction system

Abstract This paper presents a micromachined chemical reaction system, which is based on the integration of several microfluidic devices. The system is realised by anodically bonding two pumps, two flowsensors and a micromixer on top of a micromachined fluidic circuit board. The pumps are membrane pumps with piezoelectric actuation. The pumping rates are from, −220 to 490 μl/min. The flowsensors are based on the temperature difference method. The principle of the mixing/reaction chamber used for this system is diffusion because of the small value of the Reynolds number in micro-capillaries. Two fluids/chemicals join through laterally alternated inlets in order to increase the boundary surface between them. The whole system is functional and leakage through the joints does not occur. Tests have been done with ethanol, flowing through both system inlets and joining at the mixing unit.

Design and Fabrication of a Microfluidic Circuitboard

This paper reports the design and fabrication of a micromachined microfluidic circuitboard. The circuitboard consists of a Pyrex wafer in which trenches and connection holes are etched. Channels are then formed by anodically bonding a silicon wafer to the Pyrex wafer. On top of this, various microfluidic devices can be mounted via the anodic bonding technique. This allows a simple way of mass production of different microfluidic systems. To realize other microfluidic systems only the mask layout for creating the channels in the Pyrex wafer has to be changed. The microfluidic circuitboard has been successfully fabricated and single devices have been surface mounted. A whole system has been tested and it proved to be functional and without any leakage.

Time constant and lateral resonances of thermal vertical bimorph actuators

Thermal vertical bimorph actuators consist of silicon beams side-coated with aluminium. Upon heating they bend like a bimetal and produce movement in the wafer plane. We have measured the time constant describing the deflection response of the actuator to input pulses. Depending on the dimensions of the actuator, the time constant ranges from 0.5 ms to 3.8 ms. Lateral resonances of the first mode have been measured using thermal excitation and are found to be between 20 and 85 kHz.

Integrated diode detector and optical fibres for in situ detection within micromachined polymerase chain reaction chips

This paper reports on the design, fabrication, assembly and testing of a micromachined polymerase chain reaction (PCR) system with pigtailed fibre optics. Two major designs have been fabricated and tested. The first design uses two optical fibres, one for the projection of light into the chamber and the other for the collection of the light emitted by a fluorescent dye in the reaction chamber. The second design employs a single optical fibre for the delivery of light into the PCR chamber, with light now being detected using a photodiode integrated into the base and walls of the reaction chamber within the PCR chip. Tests carried out on both systems have produced promising results.

X-ray detector based on a bulk micromachined photodiode combined with a scintillating crystal

In this paper we report on the design, fabrication, assembly and testing of an x-ray detector based on a bulk micromachined photodiode (BMMPD) with a cavity filled with a scintillating crystal. The x-ray photons that reach the detector are first converted to visible light by the scintillating crystal. The visible light is then detected by the BMMPD, producing an electric current with a value proportional to the incident x-ray intensity. Tests were performed using two x-ray setups: an experimental setup and a professional setup. The first was powered with a maximum voltage of 35 kV, and a current ranging to 1 mA, and the second was powered with voltages from 40 to 60 kV and currents ranging from 10 to 55 mA.

Design and fabrication of a self-aligning gas/liquid micropump

This paper reports the design, fabrication and testing of silicon based micropump for liquid and gases. This piezoelectrically driven membrane pump is designed to be tolerant to gas-bubbles and to be suitable for self-priming. Reducing the dead volume within the pump, and thus increasing the compression ration, achieves the gas pumping. The main advantage of the pump described in the paper is the self-aligning of the membrane unit to the valve unit and the possibility of using screen printed PZT as actuator, which enables mass production and thus very low-cost micropumps. Dynamic passive valves are used, as those valves are very reliable having no moving parts and being not sensitive to smaller particles. Furthermore they can follow high frequencies, hence allowing the pump to run at resonance frequency enabling the maximum deflection of the diaphragm. First tests carried out on the micropump have produced promising results.

Design, fabrication, and packaging of closed-chamber PCR chips for DNA amplification

This paper reports the design, fabrication and packaging of a micro machined silicon/Pyrex based chip for the polymerase chain reaction. Anodic bonding is used for sealing the chambers of 1 (mu) l volume with a Pyrex glass wafer. Platinum resistors on the back of the wafer are used as heaters and temperature sensors. The chip is externally cooled by forced air to achieve rapid temperature cycling. The transparency of the Pyrex makes it possible for using optical readout methods. The packaging is especially designed for easy handling, filling, power connection, temperature regulation and optical readout. The mass production of such silicon reactors could make single-shot, disposable devices economically viable.

Packaging of closed chamber PCR-chips for DNA amplification

Reports the design, fabrication and packaging of a micromachined silicon/Pyrex based chip for the polymerase chain reaction (PCR). The anodic bonding method is used for sealing the chambers of 1μl volume with a Pyrex glass wafer. Platinum resistors on the back of the wafer are used as heaters and temperature sensors. The chip is externally cooled by forced air to achieve rapid temperature cycling. The transparency of the Pyrex makes it possible for using optical readout methods. The packaging is especially designed for easy handling, filling, power connection, temperature regulation and optical readout. The mass production of such silicon reactors could make single‐shot throwaway devices economically viable.