Abstract: A fluid sensing pipette includes an outer conductive tube forming a first electrode and an inner conductive tube forming a second electrode. The inner conductive tube is disposed concentrically within the outer conductive tube. To insulate the inner conductive tube from the outer conductive tube, the inner conductive tube is coated with a thin, uniform, and consistent Parylene coating. A hydrophobic polymeric tube is disposed concentrically within the inner conductive tube to prevent cross-contamination between different biological samples aspirated into the pipette. The inner and outer conductive tubes are separately coupled to a level detection circuit which permits the pipette to detect entry of the pipette into a conductive fluid. The level detection circuit determines the impedance between the first and second electrodes and produces a control signal in response to the impedance falling below a predetermined threshold.

Abstract: A radiation aperture system where two sets of apertures are distributed in ring sections of like radius on two parallel rings. As one ring is rotated with respect to its counterpart, one aperture of each ring will align to pass a radiation beam through both apertures. Only a single aperture pair is formed at each unique time, allowing sequential measurements of all combinations of both aperture openings during rotation without halting the rotation.