Embedded control system design for "novel micro-fluidic sensor" for the measurement of dynamic liquid interfacial tension

This paper is based on a project which was carried out to develop a novel micro-fluidic sensor for the measurement of dynamic liquid interfacial tension. Determination of the dynamic surface tension of an aqueous solution is an important parameter in many biological applications. This dynamic surface tension depends on the surfactant concentration of the solution under measurement. The surface tension is inversely proportional to the surfactant concentration of the solution up to a certain level. Above this concentration level the molecules start to cluster and form micelles. Also the surface tension remains constant. This critical concentration is called the critical micelle concentration (CMC). Conventional measurement of this surface tension can be categorized in five different groups. These are 1) Direct measurement using micro balance. 2) Measurement of capillary pressure. 3) Analysis of capillary gravity forces. 4) Gravity distorted drop. 5) Reinforced distortion of drop. All of these methods require relatively large amount of samples and lab setups are required for their measurement. So designing a hand held device using the above mentioned methods would be a difficult task. The requirement was to come up with a device to measure this surface tension with a relatively small amount of samples and measurements can be carried using a hand held device. This Novel micro-fluidic sensor for the measurement of dynamic liquid interfacial tension consists of a micro-fluidic chip with micro channel network, optical detection system and a Basic-X microcontroller. The system has potential for the measurement of surface tension using minute amount of sample liquid as compared to the present commercial forms which require large amount of solution.