Abstract: A method of estimating dimensions of an opening (36) in a body (26) comprises filling the opening (36) with a fluid that absorbs an electromagnetic radiation (40). The radiation (40) is transmitted through the body (26) and through the fluid in the opening (36). The intensity of the electromagnetic radiation, after transmission through the fluid, is determined at an area that corresponds to a radiation path through the fluid in the opening. The intensity is used to determine the absorbance of the fluid in the radiation path and consequently the length of the radiation path. In an alternative method, when the depths of the opening are already known, the intensity is used to determine concentration of a chemical in the opening.

Abstract: A micro-reactor is provided with a mixture of channels having larger cross-sectional areas (17?,22?,25?,27?,31?,33?) and channels having smaller cross-sectional areas (40a?,40b?,40c?). The smaller channels (40a?,40b?,40c?) resist liquid movement driven by hydrostatic force but allow liquid movement driven by electro-osmotic force. Accordingly liquid flow is almost entirely driven by electro-osmotic force. The smaller channels (40a?,40b?,40c?) are formed by etched grooves which are closed by a planar surface 13. This allows the cross-sectional areas of the smaller channels to be closely and reproducibly controlled.

Abstract: A reaction is performed in a micro-reactor (10), voltages being applied by a power supply (12), under the control of a processor (14), so as to cause the reagents to move and react in the channels (24?,30?,32?,34?,36?) of the micro-reactor (10). The power supply (12) also measures currents in the channels and relays this information to the processor (14). The currents are used to monitor progress of the reaction.

Abstract: A microchip device has at least one passage along which a liquid can be moved by applying a voltage to the liquid. The device includes a passage member (10, 12) in which the passage is formed and which has an aperture (20, 22). Additionally the device includes an electrode member (14) that comprises an electrode (42, 44) and that is separably engageable with the passage member. The device includes a reservoir in fluid communication with the passages for holding a liquid. The electrode member cooperates with the aperture so that the electrode is in fluid communication with the passage without the electrode member obstructing the opening of the reservoir.

Abstract: A micro-reactor is provided with a mixture of channels having larger cross-sectional areas (17′,22′,25′,27′,31′,33′) and channels having smaller cross-sectional areas (40a′,40b′,40c′). The smaller channels (40a′,40b′,40c′) resist liquid movement driven by hydrostatic force but allow liquid movement driven by electro-osmotic force. Accordingly liquid flow is almost entirely driven by electro-osmotic force. The smaller channels (40a′,40b′,40c′) are formed by etched grooves which are closed by a planar surface 13. This allows the cross-sectional areas of the smaller channels to be closely and reproducibly controlled.

Abstract: A reaction is performed in a micro-reactor (10), voltages being applied by a power supply (12), under the control of a processor (14), so as to cause the reagents to move and react in the channels (24′,30′,32′,34′,36′) of the micro-reactor (10). The power supply (12) also measures currents in the channels and relays this information to the processor (14). The currents are used to monitor progress of the reaction.

Abstract: A method of estimating dimensions of an opening (36) in a body (26) comprises filling the opening (36) with a fluid that absorbs an electromagnetic radiation (40). The radiation (40) is transmitted through the body (26) and through the fluid in the opening (36). The intensity of the electromagnetic radiation, after transmission through the fluid, is determined at an area that corresponds to a radiation path through the fluid in the opening. The intensity is used to determine the absorbance of the fluid in the radiation path and consequently the length of the radiation path.

Abstract: A microchip device has at least one passage along which a liquid can be moved by applying a voltage to the liquid. The device includes a passage member (10,12) in which the passage is formed and which has an aperture (20,22). Additionally the device includes an electrode member (14) that comprises an electrode (42,44) and that is separably engageable with the passage member. The device includes a reservoir in fluid communication with the passages for holding a liquid. The electrode member cooperates with the aperture so that the electrode is in fluid communication with the passage without the electrode member obstructing the opening of the reservoir.