The objective of this project is the development of an optical detection scheme for the detection of ultrasmall amounts of viruses used in biowarfare and in potential terrorist attacks. Because of their small size, viruses cannot be detected with existing techniques in real-time and on a single particle level. The proposed scheme is based on elastic light scattering and differential interferometry. A microfluidic channel transports viruses and other particles through a tightly focused laser beam and the interference between the scattered field and the primary laser field is monitored by a split photodiode. The interferometric detection will be combined with simultaneous spectroscopic measurements such as fluorescence or Raman scattering. This spectroscopic information in combination with the interferometric signal will provide a highly specific fingerprint and detection threshold for the particle to be detected. The device will work in real-time and with single-particle sensitivity which is of critical importance for the early recognition and tracking of terrorist threats.
