Liquid-crystal materials find a new order
With the maturation of the information display field, liquid-crystal materials research is undergoing a modern-day renaissance.
doi:10.1038/nindia.2007.53 Published online 18 December 2007
Liquid-crystal materials have often been referred to as a curious phase of matter, but their impact on modern technology has been profound. With the roots of their discovery in derivatives of cholesterol, liquid crystals are materials that biologists and biomedical engineers observe and manipulate daily. Their science and technology is truly interdisciplinary, combining basic aspects of physics, chemistry, biology and engineering. Composed of anisotropic organic molecules, liquid crystals interact with external fields and surfaces, which strongly influence their structure and properties (see Box 1). But the primary scientific and technological revolution brought about by this intriguing set of materials has been in the field of information displays, rather than the biosciences.
With the maturation of the liquid-crystal display market (see ), the question of 'what's next?' pervades the research community. Liquid-crystal science is ripe for translation into new and exciting domains of knowledge. There is perhaps no direction more appropriate for researchers in liquid crystals than the field from which their knowledge first came — the biosciences. From a basic science perspective, the fundamental theories and See Figure 1models of liquid crystals have percolated through many scientific communities; for example, the concepts of orientational order and collective molecular behaviour are central to the modern understanding of the biosciences, contributing to the dynamics of cell membranes, functioning muscles and morphogenesis1,.
See Figure 2Here, we focus on early successes for new liquid-crystal material applications with notable biomedical implications (see box 2). Three primary areas of application are presented: optical devices using liquid-crystal materials for integration into spectroscopy, microscopy and imaging systems; biosensor devices direchttp://beta-pubadmin.nature.com/articling/nindia/articles/1805# Addtly interfacing with liquid-crystal materials for improved optical imaging and diagnostics; and liquid-crystal materials that mimic biological materials and systems. Although these areas are not a complete description of the potential of liquid-crystal materials for biology and medicine, they represent a gateway to further advances. In conjunction with the primarily experimental developments discussed here, there have been widespread advances in theoretical modelling and computer simulation of liquid-crystal systems, with a particular emphasis on the biomedical interface.
The origins of the liquid-crystal field lie within the study of biological materials. In 1888, the Austrian botanist Friedrich Reinitzer observed the melting behaviour of an organic substance related to cholesterol, specifically cholesteryl benzoate. Discussion with Otto Lehmann led to the identification of a new phase of matter, termed the liquid-crystal phase. Soon afterward, Lehmann confined this unusual material to droplets, which would become the basis for a modern-day technology known as polymer-dispersed liquid-crystals (PDLCs), developed more than 80 years later.
- Stewart, G. T. Liquid crystals in biology. I. Historical, biological and medical aspects. Liquid Cryst. 30, 541-557 (2003).
- Stewart, G. T. Liquid crystals in biology. II. Origins and processes of life. Liquid Cryst. 31, 443-471 (2004).