Simple Micropump Research Articles

A simple micropump based on a freeze-dried superabsorbent polymer for multiplex solution processing in disposable devices.

We describe a simple micropump for disposable microfluidic devices. The pump is constructed using a freeze-dried disc of a superabsorbent polymer (SAP). The disc absorbs a solution in a flow channel and swells upward in a pumping chamber. Despite the simple structure of this device, the rate of absorption remains constant and can be adjusted by changing the composition of the SAP, its size, the dimensions of the flow channel and the medium to be absorbed. The pumping action can be initiated by applying an electrical signal using a switchable hydrophobic valve. The integrated approach of the SAP pump and switchable valve could facilitate the automatic processing of many solutions required for bioassay.

Development of the orthogonal microrobot for accurate microscopic operations

In this paper, we describe the development of an orthogonal microrobot for accurate microscopic operations. To conduct the microscopic operation, a simple locomotion mechanism composed of one piezoelectric actuator and two U-shaped electromagnets is proposed. The orthogonal microrobot can move precisely in one-axis with the manner of an inchworm. We use permanent magnets so that this robot can fix itself on a steel surface when no voltage is applied. To provide XY orthogonal positioning, we connect one microrobot to another microrobot orthogonally. To realize cell processing, we arrange the three two-axial orthogonal microrobots on an inverted microscope. We load a simple micropump on right and left robots to hold biological samples such as an egg cell and to inject reagent solutions into biological samples. Finally, we arrange another microrobot between the other two microrobots to position samples. The whole cell processing device is very small, so we can easily set up the whole device to microprocessing instruments. In experiments, orthogonal microrobots succeeded in holding an egg cell with a diameter of 100 μm and sticking the pipette with a diameter of 5 μm into the egg cell under a specific GUI control system with a visual feedback function.

Design and fabrication of an electrochemically actuated microvalve

A microfluidic valve based on electrochemical (ECM) actuation was designed, fabricated using UV-LIGA microfabrication technologies. The valve consists of an ECM actuator, polydimethylsiloxane (PDMS) membrane and a micro chamber. The flow channels and chamber are made of cured SU-8 polymer. The hydrogen gas bubbles were generated in the valve microchamber with Pt black electrodes (coated with platinum nanoparticles) and filled with 1 M of NaCl solution. The nano particles coated on the working electrode helps to boost the surface-to-volume ratio of the electrode for faster reversible electrolysis and faster valve operation. To test the functionality of the microvalve, a simple micropump based on ECM principle was also integrated in the system to deliver a microscopic volume of fluid through the valve. The experimental results have showed that an approximately 300 μm deflection of valve membrane was achieved by applying a bias voltage of −1.5 V across the electrodes. The pressure in the valve chamber was estimated to be about 200 KPa. Experimental results proved that the valve can be easily operated by controlling the electrical signals supplied to the ECM actuators.

A microfluidic ‘blinking bubble’ pump

The paper reports data obtained on a simple micropump, suitable for electrolytes, based on the periodic growth and collapse of a single vapor bubble in a microchannel. With a channel diameter of the order of 100 µm, pumping rates of several tens of µl/min and pressure differences of several kPa are readily achieved by the system. The pump is notable for its effectiveness, simplicity, absence of mechanical moving parts, robustness and low cost. In the absence of a complete theory for the device, the data are interpreted and rationalized on the basis of simple physical arguments. It is also shown how the pump can induce strong mixing in two channels coming together at a Y-junction.

Modelling and test of a thermally-driven phase-change nonmechanicalmicropump

A thermally driven phase-change nonmechanical micropump hasbeen investigated theoretically and experimentally. This micropumpconsisted of a microchannel and a number of uniformly-spaced heatingelements along the channel. The pumping of fluids in such a pump wasrealized by using the actuation of a moving vapour slug (bubble)generated by suitably phased heating elements. The pumping mechanismwas studied theoretically by considering a liquid-filled tube heatedlocally by a moving heating source. To verify the theoreticalanalysis, a pumping device consisting of a microchannel with twelveembedded heaters along the channel was fabricated and tested usingdeionized water as the working fluid. The experimental resultsindicate that this simple micropump can achieve a maximum pressurehead of 57 mm H2O and a maximum volumetric flow rate of300 µl min-1 when it is operated for a heating power rangingfrom 8.0 to 12.0 W and a heating time of about 3 s. It is found thatthe theoretical model is in reasonable agreement with theexperimental data.

2724 蒸気泡駆動型マイクロポンプの作動原理とその特性

A novel simple micropump driven by bubble generated by D.C. heating was developed and investigated. The pump consists of a glass tube narrowed in the middle and heater located at the conical region of tube. Observation of the bubble with a high speed video or by detecting displacement of laser passed working fluid near the heater showed that bubble generates, travels toward widening direction and collapses periodically. Pump performance of maximum pressure of 400Pa and maximum flow rate of 40μl/min was measured. The maximum pressure for various pumps was related to minimum diameter of the tube. It was shown from both experiment and numerical simulation using a simple model that driving force of the pump is made by surface tension effect. The simulation showed that taking evaporation and condensation of bubble into theoretical model is important for predicting the bubble behavior and the pump performance.