Liquid Crystal Sensors for Volatile Organics

SUMMARY Aromatic volatile organic compounds aVOCs such as benzene toluene ethylbenzene and xylenes BTEX depress the central nervous system upon short term exposure and upon long term exposure can lead to reproductive system damage and dermatitis Benzene present in gasoline and crude oil and one of the twenty most common chemical manufacturing materials in the US is carcinogenic As the American Petroleum Institute stated in the only absolutely safe concentration of benzene is zero aVOCs are difficult to detect and measure due to their lack of reactivity This makes corrective actions and exposure awareness difficult To address the increased concern over ambient levels of aVOCs this proposal seeks to develop and validate a new sensing mechanism for aVOCs based on liquid crystals LCs The proposed LC sensor technology will enable development of low cost sensors for widespread personal exposure monitoring and warning Such sensors are timely as the NIEHS strategic plan for includes a major focus on enhancing our ability to quantify individual exposures and responses to environmental toxins The commercially available options of infrared photoionization and metal oxide detectors are cost prohibitive for personal and environmental monitoring as increased sensitivity and accuracy are needed the cost rises limiting the number of sites and personnel that can be monitored and devices also become too large to be worn There is thus an unmet need for more compact more affordable accurate sensitive devices to measure aVOCs in real time across a range of concentrations that are relevant to both personal and environmental monitoring Whereas Platypus Technologies has previously developed LC sensors for reactive gases this proposal seeks to establish proof of concept for a fundamentally new approach applicable to non reactive aVOCs The advances in technology required to meet this new challenge are substantial and include development of a new sensor design elastically strained LCs and surface chemistry fluorphenyl surfaces The risks inherent in this project justify support via the Phase I SBIR mechanism The two main technical aims of this Phase I SBIR project focus on ways to enhance and tune sensitivity first capitalizing on the recently discovered phenomenon of using elastically strained LCs for sensitive target detection and second through development of a novel surface chemical interaction that is uniquely applicable to sensing of aVOCs using LCs The outcome is anticipated to be proof of principle that these approaches can form the basis of compact robust inexpensive accurate sensors suitable for detecting a broad range of aVOC vapor concentrations in the workplace and environment Narrative Aromatic volatile organic compounds aVOCs especially benzene are carcinogenic and impact respiratory and reproductive health leading regulatory agencies to impose exposure limits for workers in industries where aVOC exposure is a risk and for the broader environment Available devices for detecting aVOCs in the workplace are expensive and only the most expensive devices are capable of monitoring the very low levels of benzene in the environment in real time This Phase I proposal aims to test the feasibility of fabricating simple low cost sensors based on the company s liquid crystal sensing platform that incorporate novel physico chemical approaches designed to enable real time monitoring of VOCs over a broad dynamic range from a few parts per billion to hundreds of parts per million