Kinesin is a microtubule-associated protein, converting chemical into mechanical energy. Based on its ability to also work outside cells, it has recently been shown that this biological machinery might be usable for nanotechnological developments. Possible applications of the kinesin-based motor system require the solution of numerous methodological and technical problems, including the orientation of force generation into a desired direction and the determination of the tolerable roughness of the surfaces used, the minimal free vertical space still enabling force-generating activity, and the temporal stability of the system. This paper reports on the example of microtubules gliding across kinesin-coated surfaces and shows that the force-generating system needs a minimal free working space of about 100 nm height and works up to 3 h with nearly constant velocity. Individual microtubules were observed to cover distances of at least 1 mm without being detached from the surface and to overcome steps of up to 286 nm height. In addition, mechanically induced flow fields were shown to force gliding microtubules to move in one and the same direction. This result is regarded as being an essential step towards future developments of kinesin-based microdevices as this approach avoids neutralization of single forces acting in opposite directions.

In this article, we present a technical description of a new type of anemometer for gas and especially liquid flows with high temporal and spatial resolution. The principle of the measurement is based on the atomic force microscope technique where microstructured cantilevers are used to detect extreme small forces. We demonstrate the working principle and the design of the sensor, as well as calibration measurements and initial measurements of turbulent flows, which were performed in air and water flows.

Summary: We describe the development of different drop‐on‐demand systems particularly for applications for the liquid handling of biopolymers. Different designs of drop‐on‐demand systems developed by the authors are described. Experiments with these systems show the applicability for pipetting different liquids with different properties. Commercially available systems are also tested. A comparison of the different approaches leads to a discussion of the best fields of application of the different approaches or, alternatively, to the potential further development of the drop‐on‐demand technologies.Principle setup of the print heads.magnified imagePrinciple setup of the print heads.

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