Manabu Tokeshi

Micro/Nano Devices for Chemical Analysis

Since the concept of micro total analysis systems (µ-TAS) has been advocated, various kinds of micro/nano devices have been developed by researchers in many fields, such as in chemistry, chemical engineering, mechanical engineering, electric engineering, biology, and medicine, among others.[...].

Subsingle-molecule determination of nonfluorescent species by scanning thermal lens microscope and its application to single-cell measurement

We have developed a thermal lens microscope which indices and detects photothermal effect at sub-single molecules level in/on liquids and condensed media. The thermal lens microscope can determine non-fluorescent molecules without receiving serious effects of light scattering in/on various condensed phase substances, and it can be applied to imaging of the distribution of non-fluorescent molecules by scanning on the sample. These characteristics of the thermal lens microscope are suitable for ultra sensitive analysis and imaging of biomedical substance in/on a single cell, separation media, and microfabricated chemical devices. We applied the thermal lens microscope to determine an ultratrace chemical species in various media.

Integration of photothermal spectroscopy detection system on a chip

Miniaturization of sensitive detection system is a key factor for integrated chemical systems. Thermal lens microscope can be applied to the ultra-sensitive detection of non-fluorescent molecules in many applications. By using a very small SELFOC micro lens as an objective, palmtop- sized thermal lens microscope (PTLM) has been constructed. A calibration curve for an aqueous solution in a range of 1.0 by 10-7-5.0 by 10-6 mol/L has been measured in this newly designed PTLM.

Integration of Immunosorbent Assay System into a Multichannel Microchip for Clinical Diagnoses

The whole process of an immunosorbent assay system was integrated into a glass microchip. Analyte was adsorbed on polystyrene beads put in a microchannel, and then the antibody conjugated with colloidal gold was reacted. The colloidal gold bound to the beads was detected by a thermal lens microscope. By using a microchip with a multichannel system, simultaneous determination became possible. This system seems to be practically useful to clinical diagnosis. Moreover, troublesome operations required for the conventional immunosorbent assay were replaced by simple operations.