Abstract: A method for automatically adjusting a dispensing tip from a surface onto which liquid is to be dispensed, a proper distance that precludes the dispensing stream from puddling up, or from breaking apart. The method features the formation on the tip of a meniscus of a nominal small volume and advancing the tip and meniscus until the surface is contacted. The resulting decrease in pressure in the tip is measured, to trigger the tip to stop its advance and to start dispensing. In circumstances wherein the contacted surface is hydrophobic so as to ideally require a meniscus depth greater than the nominal depth, the tip is retreated from the surface, during dispensing, to the ideal depth.

Abstract: There is disclosed a method for injecting liquid into a container that senses the location of the bottom of the container, not simply by the force of "running into" the container, but rather, by first sealing the dispensing orifice against the bottom of the container, pressuring the liquid in the orifice and then backing off the orifice until release of liquid out the orifice is sensed.

Abstract: A method and apparatus for detecting an erroneous pre-spotting of liquid onto a test element in an analyzer. The invention utilizes a wetness detector and calculates the estimated second derivative of the R-C time decay curve produced by such a detector, to determine if a sudden increase in a slope exceeds more than a threshold value for two consecutive points. The threshold value is picked so as to exceed sudden increases that can be created by noise in the system.