Portable biometric system of high-sensitivity absorption detection

The purpose of this paper is to design a portable biometric system that can measure the amount of absorption of the visible collimated beam that passes by the sample to know the absorbance of the sample. The measured object in the system is the gold colloid that the sample produces after a biochemical reaction. After measuring the absorbance of the gold colloid, we can obtain the concentrations of the waiting‐measured sample and further obtain the concentration of chemical solution contained in the sample. Normal single optical path system has a sensitivity of 0.5%.The process of the double optical path method increases the opportunities that the visible collimated beam is absorbed, which raise the detection sensitivity of the system to a sensitivity of 0.1%. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 868–871, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23249