Abstract: A method of detecting the presence, absence or quantity of a dye in a sample in a reaction region is provided, comprising the steps of providing a dye comprising a ligand ion complex, the ligand having a lowest unoccupied electron level and the ion having an excited electron level, the lowest unoccupied electron level of the ligand having an energy level such that an electron in the excited electron level of the ion may transfer non radiatively to the lowest unoccupied electron level of the ligand, the complex having a ground state electron level; illuminating the dye with a specified wavelength of radiation to detect the presence, absence or quantity of dye; detecting radiation from the illuminated dye; wherein the electron levels of the complex and the wavelength of the radiation are arranged such that electrons in the ground state are promoted to an excited state by photon absorption and it is energetically favourable for electrons to transfer to the lowest unoccupied electron level of the ligand from the

Abstract: Methods of electrochemically monitoring enzyme-substrate reactions are described. The substrate is tagged with a redox-active group. Modification of the substrate by an enzyme can then be monitored electrochemically by means of the redox-active group. Such methods can be used in particular to monitor non-redox enzyme reactions, such as kinase, phosphatase, or protease reactions, although redox enzyme en reactions can also be monitored by such methods. Screening assays to identify modulators of enzyme activity or new enzyme substrates are also described.

Abstract: A valve for controlling fluid flow in a microfluidic device is provided. The valve comprises a chamber (26) formed on a substrate (24), a heating coil (42), and a valve material (30) contained in the chamber (26). When the valve is to be closed, the heating coil is activated causing the valve material to expand out of the chamber, through a neck portion (28), and into the main channel (22), blocking it. Preferably, the valve material is paraffin wax, and is caused to melt by the heating coil (42). On melting the melted paraffin wax flows into the main channel whereupon it cools and solidifies. A restriction (34), with collar (36) provides a cool surface on which the solidifying wax accumulates.

Abstract: A method of detecting the presence or absence of an analyte in a sample uses an analyte carrier with a calibration dye held in a region near a metal surface. A reporter dye is held away from a region near the metal surface and is displaceably attached to a selective agent. The selective agent is capable of binding to an analyte so that when the analyte binds to the selective agent the reporter dye detaches and moves to a region near a metal surface. The difference in response to illumination from the reporter dye and calibration dye can be used to detect the presence, amount or absence of an analyte sample.