A Squeegee Coating Apparatus for Producing a Liquid Crystal Based Bio-Transducer

Abstract

Cholesteryl ester liquid crystals were discovered with a new application in sensing traction forces of single cells. The liquid crystal bio-transducer is produced by manual scraping of liquid crystals onto the petri dish, in which the technique is highly subjective to the skill of the user to produce homogeneously spread liquid crystal substrates. This paper describes the development of an apparatus used to produce a liquid crystal substrate using squeegee coating technique. It consists of a biaxial mechatronic system which is synchronously controlled in vertical and horizontal directions scraping the liquid crystal substrates evenly on the surface of a petri dish. The thickness of the liquid crystal was profiled using laser diffraction technique and the homogeneity of the liquid crystal films produced was examined in a crossed-polarizing microscope. At an angular speed of 1500 rpm and under a shear stress of 1.46 ± 0.72 kPa, the squeegee coating was found producing liquid crystal films at a thickness of 132 ± 23 μm on the surface of petri dishes. With the application of this apparatus, evenly spread liquid crystal coatings with control thickness in petri dishes were consistently produced. This has overcome the major problem of manually coating the liquid crystal substrates using a cell scraper.