Liquid Crystal-Based Sensors for Environmental Monitoring

Oral Presentation

Prepared by B. Grinwald
Platypus Technologies LLC, 5520 Nobel Drive, Suite 100, Madison, WI, 53711, United States

Contact Information: [email protected]; 608-237-1270


Environmental measurements are critical to understanding pollutants and implementing corrective actions. However, the expense and complexity of the instruments and analytical chemistry techniques routinely used to provide high-quality measurements limit the number of measurements that are made. Liquid crystal (LC) sensing technology offers a new paradigm of simple, low-cost sensors that deliver high-quality measurement results. The LC mechanism utilizes different chemical interactions than other measurement technologies, thereby providing new sensing capabilities. A LC-based gas sensor is made by spreading a thin film of LC over a chemically functionalized surface. The detection chemistry aligns the LC molecules in one orientation before exposure to the target, then in a different orientation after interaction with the target. The change in LC orientation appears as a change in brightness when viewed through crossed polarizers. This provides a much simpler means to read out chemical interactions than sophisticated instrumentation, requiring no electrical power and providing visual results on-site. This use model is ideally suited to citizen science and participation; LC-based sensors can be used for widespread environmental screening to identify hot spots and focus additional efforts. A LC-based dosimeter for hydrogen sulfide has been released for use in industrial hygiene applications, and sensors for ammonia, nitrogen dioxide, formaldehyde and other volatile organic compounds are in development. Applications range across air monitoring, fenceline monitoring, atmospheric research, in-home sampling, indoor air quality, personal exposure monitoring, epidemiological studies, safety and industrial hygiene.