Abstract: There is disclosed a method of making a filter element or mouthpiece (300) comprising the steps of: advancing filtering material in the longitudinal direction; drawing the advancing filtering material into a shaping element (110), to thereby form a longitudinally extending rod of filtering material comprising a channel extending longitudinally through the rod of filtering material; wherein the shaping element (110) comprises a chamber and a shaping rod (200) which extends longitudinally within the chamber, the inner surface of the chamber shaping the advancing filtering material to form the longitudinally extending rod of filtering material, and the shaping rod (200) shaping the advancing filtering material to form the channel extending longitudinally through the rod of filtering material; and wherein the shaping element (110) applies an additive to the filtering material.

Abstract: A sensor device for the analysis of a sample fluid comprises a substrate in a surface of which an elongate channel is micromachined. The channel contains a material, such as a starch, agarose, alginate, carrageenin or polyacrylic polymer gel, with a biological material for causing separation of the sample fluid as the fluid passes along the channel. The biological material may comprise, for example, a binding protein, an antibody, a lectin, an enzyme, a sequence of enzymes or a lipid. Pairs of sensing electrodes are spaced apart along the walls of the channel. The device may be used, for example, for testing blood samples.