An orientation structure of polyimide film, which is introduced by rubbing in liquid crystal device (LCD) fabrication, is clarified by polarized infrared spectroscopy. Samples rotated in-plane around the polarized incident beam reveal that the orientation direction of the rubbed polymer chain coincides with the rubbing direction. A sample-tilt measurement, in which the sample is tilted around the vertical axis, reveals that the polymer chains are tilted at an angle to the substrate surface. A simple model is proposed in order to estimate the thickness of the oriented layer of the rubbed film. In the model, the degree of dichroism of parallel and perpendicular polarized IR spectra is calculated as a function of polymer film thickness. Comparing the model with experimental data, it is determined that the thickness of the oriented layer is less than 14 nm.

A portable fluorescence polarization imaging analyzer was developed for high-throughput fluorescence polarization immunoassay.

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Fluorescence polarization (FP) offers easy operation and rapid processing, making it implementable in molecular interaction analysis. Previously we have developed a unique FP measurement system using a liquid crystal (LC) layer and an image sensor. The system is based on a principle of synchronized detection between the switching rate of the LC layer and the sampling rate of the CCD. The FP system realized simultaneous multiple sample detection; however, the measurement precision was lower than that of the conventional FP apparatus. The main drawbacks were low light transmittance of the LC layer and insufficient synchronization between the LC layer and CCD. In this paper, we developed a new FP analyzer based on LC-CCD synchronization detection. By using a newly designed LC with high transmittance and improving synchronization, the performance of the system has been dramatically improved. Additionally, we reduced the cost by using an inexpensive CCD and an LED as the excitation source. Simultaneous FP immunoassay of multiple samples of prostaglandin E2 was performed. The error rate of the FP system is reduced from 16.9% to 3.9%, as comparable to the commercial conventional FP system.