A Fast Optical Method for the Determination of Liquid Levels in Microplates
Parallel liquid handling systems are widely used in different applications of life sciences. In order to avoid false positive or negative results which lead to higher costs due to the replication of the experiments it is necessary to monitor the process and success of liquid delivery. An easy method for the determination of the liquid levels in microplates has been developed and evaluated. The optical method bases on the measurement of the liquid level using CCD cameras followed by special algorithms for the evaluation and visualization of the measured data. The proposed method was tested in changing environmental lighting for two different liquids. These tests confirm our approach towards optical liquid level determination for smallest volumes in microplates and also show the challenges regarding environmental lighting and different physical properties of fluids.
Noncontact level sensing technique using computer vision
Various types of sensors have been developed for measuring the depth of liquids in tanks, such as a fuel tank in an aircraft. Almost all of these methods require the sensor to come in contact with the liquid with low-voltage electrical leads carrying the signal from the sensor to an external computer for processing. A particular concern when such in-contact sensors are used in fuel tanks is the potential for an electrical discharge through the sensor leads resulting in an explosion. In this paper, we propose a computer vision-based noncontact technique for measuring the level of a liquid in a closed container using an optical imaging system coupled with an appropriate set of image-processing algorithms. An experimental setup was specially designed and constructed for simulating the environment of vibrating fuel in the gas tank of aircrafts for demonstrating the effectiveness of the technique. The experimental results of this paper may be used for studying the feasibility of implementing an actual system, which could be incorporated in aircrafts as a part of the aircraft's fuel gauge system.
A low-cost contactless distance meter for automotive applications
This paper describes an ultrasonic sensor that is able to measure the distance from the ground from selected points of a motor vehicle. The sensor is based on the measurement of the time of flight of an ultrasonic pulse, which is reflected by the ground. An uncertainty of 1 mm (1 /spl sigma/) is obtained at rest or at low speeds; the sensor still works at speeds of up to 30 m/s although at reduced accuracy. Such a performance is obtained by employing a series of optimisations that allows the sensor to self-adapt to different conditions to give the best results. The sensor is composed of only low cost components, thus being apt for first car equipment in many cases.