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A thermal cycling method, whereby capillary tubes holding polymerase chain reactions are subjected to programmed tilt displacements so that they are moved using gravity over three spatial regions (I, II, and III) kept at different constant temperatures to facilitate deoxyribonucleic acid (DNA) denaturation, annealing, and extension, is described. At tilt speeds in excess of 0.2 rad/s, the standard deviation of static coefficient of friction values was below 0.03, indicating in sync movement of multiple capillary tubes over the holding platform. The travel time during the acceleration phase and under constant velocity between adjacent regions (I to II and II to III) and distant regions (III to I) was 0.03 s and 0.31 s, respectively. The deviations in temperature did not exceed 0.05 °C from the average at the prescribed denaturing, annealing, and extension temperatures applied. DNA amplification was determined by optical readings, the fluorescence signal was found to increase twofold after 30 thermal cycles, and 1.16 × 106 DNA copies/μl could be detected. The approach also overcomes problems associated with thermal inertia, sample adhesion, sample blockage, and handling of the reaction vessels encountered in the other thermal cycling schemes used. [ABSTRACT FROM AUTHOR]

A vast majority of syringe pumps operate on stepper motors, which limits their effectiveness for precision fluid delivery using estimation algorithms. Such a system also hampers the ability to ascertain if the infusion or aspiration instruction has been correctly carried out in the event of power interruptions. To address this issue, a linear servo based actuator system is described to provide absolute indications of the plunger position. System performance in terms of linearity and reliability of plunger translation were verified using a camera tracking system with syringe capacities ranging from 3 to 50 ml and at syringe plunger speeds ranging from 1 to 6.6 mm/s when distilled water was used as the medium. In investigations involving more viscous liquids, the system revealed similarly linear characteristics with 50% glycerol-water (v/v), but cyclical stick-slip behavior with Freund's adjuvant. [ABSTRACT FROM AUTHOR]