Development of fiber optic liquid crystal sensor for pressure measurement

The paper presents a further development of a novel fiber optic low and high hydrostatic pressure sensing technique utilizing new classes of chiral nematic liquid crystals with a significantly reduced thermal sensitivity. The low-pressure sensor (up to 1 MPa) is based on polarization effects caused by strong rotatory power of chiral nematics and pressure-induced deformations of a twisted nematic cell. The high-pressure sensor (up to 60 MPa) is based on intensity phenomena occurring in novel classes of chiral nematics with induced smectic A_d phase. The latest results indicate that our method of hydrostatic pressure measurement offers high response to pressure with reduced temperature sensitivity and, depending on the employed configuration and on the liquid crystalline sensing head, can be pre-set for a required range of pressure