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This paper describes a simple system for the actuation of a biological fluid through micro-channels with a thermoactivated polymer actuator. This system is of interest for the development of single-use diagnostic test-strips since the actuation of the sample is integrated in the disposable test strip. On chip actuation has the advantage of reducing the size and the cost of the non disposable part of the measurement system and preventing any contamination of the sample since it is completely isolated from any non- disposable elements. The study of the developed system was done optically by monitoring the fluid progression in the channel. It has demonstrated typical flow range of 10 to 60 nl/min. A similar device was then used to prove its application to blood coagulation characterization based on an increase in blood viscosity. Such a system can find diverse applications in chemical analysis and diagnostics on chip where actuation by steps from nano to microliter range is required.

Anti-coagulation treatments are required for medical conditions that become more and more frequent with the ageing of the population in developed countries (atrial fibrillation, deep-venous thrombosis, heart prosthetic valves, etc.). These treatments generally use coumarin derivative (vitamin-K antagonist), whose activity needs to be monitored in order to keep the patient in an appropriate therapeutic range. This measurement can be done in laboratories but can also be performed by the patient himself using portable devices. This paper presents the different technological ways to selfmonitor vitamin-K antagonist treatment by measuring coagulation time. It will focus on portable devices, well suited to be used at home and on device to be manipulated by the patient, thus not requiring an extensive training nor sample treatment.

We present a simple pneumatic setup for easy and precise control of pairs of inlet flows for lab on a chip applications.

Microfluidic devices are increasingly used to perform biological experiments on a single-cell basis. However, long-term stability of cell positions is still an issue. A novel biocompatible method for cell entrapment and release on a microchip is presented. It is based on the controlled formation of an alginate hydrogel by bringing two laminar flows of alginate and calcium ions in the range of 2 mM to 40 mM into contact. The resulting growth of a gel bar is used to enclose and immobilize yeast cells. Adding ethylenediaminetetraacetic acid (EDTA) to the alginate solution allows for control of the hydrogel growth, and by varying the ratio of Ca(2+) to EDTA concentrations gel growth or gel shrinkage can be induced at will. Trapped cells are released during shrinkage of the gel. The trapping efficiency for different cell speeds is investigated and the properties of gel growth are discussed using a diffusion model. Precise positioning of a single cell is demonstrated. The technique presented allows not only the reversible immobilization of cells under gentle conditions but also offers the potential of long-term cell cultures as shown by on-chip incubation of yeast cells. The procedure may provide a simple and fully biocompatible technique for a multitude of innovative experiments on cells in microsystems.

This work reports the demonstration of a thermopneumatic microfluidic actuator used to determine blood coagulation time. In this new system, the detection principle is the obstruction of a microfluidic channel by clotted blood. The sample actuation is done by aspiration due to air cooling in a cavity. We made a study of the position of the blood plug depending on the presence in the channel of coagulation reagent and observe a slowdown of the plug on a coated channel compared to a blank one.

A contactless microfluidic dosing system based on actuation by an electrochemical reaction has been designed and tested. The device is composed of two chambers separated by a polydimethylsiloxane (PDMS) plate. One chamber is loaded with the liquid sample to be dosed while the electrochemical reaction occurs in the second chamber. Due to the strict separation between the reaction responsible of the actuation and the sample, the latter is preserved from contamination and/or electrochemical modification. Silicon master microstructures were fabricated using clean-room technologies and subsequently replicated into the PDMS. A full microsystem has been fabricated and tested. Microliter sample solutions can be easily and reproducibly dispensed in a time frame of a few tens of seconds.