Minute particle detection using a light-wave-guide incorporated optical total analysis system

An optical sensor combined total analysis system (TAS) is thought to be one of the most effective functional elements in realizing a ubiquitous human healthcare system. In accordance with this concept, we have proposed a fundamental structure of a light-wave-guide incorporated TAS and have developed a micro fluidic channel fabricated chip, where two light waveguides having approximately 10-μm cores were facing each other across a fluidic channel with a width of 12 μm. By passing 5-μm-diameter polystyrene particles across the portion where a light-wave-guide and the fluidic channel intersect at a right angles, we confirmed that changes to transmitted light and scattered light were detectable even with an extremely low laser source power of 5 μW, and they increased proportionally as the introduced laser power became higher. Increasing the introduced laser power clearly increased the correlation between the transmitted and scattered light change. Here we discuss in detail the two different correlation tendencies that appeared in the correlation maps.