The present invention provides a water tension sensor with a non-sintered core that allows batches of similar and standard sensors to be manufactured in a simple manner, for operation with air and with an air flow outlet, which sensor can be used to read water tension and trigger dripping. The sensor according to the invention is ideal for manually reading soil water tension and for automating irrigation systems based on a static pressure or gas propulsion mechanism.

A method for determining physical parameters of an unknown liquid to be aspirated and/or dispensed by a laboratory automation device comprises: determining physical parameters of a pipette, the physical parameters including geometric parameters of the pipette, which at least include a tip radius of an orifice of the pipette; aspirating and/or dispensing the unknown liquid with a pipette of the laboratory automation device and measuring a measured pressure curve in the pipette during aspirating and/or dispensing; determining the physical parameters of the unknown liquid by minimizing an objective function depending on a difference between a simulated pressure curve and the measured pressure curve, wherein the simulated pressure curve simulates a pressure in the pipette during aspirating and/or dispensing and is calculated based on a physical model of the laboratory automation device including the physical parameters of the pipette.

A method for determining physical parameters of a liquid to be aspirated and/or dispensed by a laboratory automation device comprises: picking up of a pipette with the laboratory automation device; lowering the pipette into a sample container with the laboratory automation device, the sample container containing the liquid; aspirating and dispensing air and liquid with the laboratory automation device in such a way, that a liquid level in the pipette solely rises in a first step and solely lowers in a second step, such that an interior surface of the pipette is wetted with liquid solely one time; and during aspirating and dispensing air and liquid, measuring a pressure curve in the pipette and determining the physical parameters from the pressure curve, the physical parameters comprising at least one of a surface tension, a wetting angle and a viscosity.