Chemical engineers developed a way to create inexpensive chemical sensors for detecting explosives, industrial pollutants, and chemical makers of disease in a person’s breath



Chemical engineers at the University of Wisconsin-Madison have
developed a new way to create inexpensive chemical sensors for detecting
explosives, industrial pollutants, or even the chemical markers of disease in a
patient’s breath.

The idea came from two chemical and biological engineering professors,
Manos Mavrikakis and Nicholas L. Abbott. By combining their expertise in
computational chemistry and liquid crystals, the duo turned a sensor Abbott
built to detect a molecular mimic of deadly sarin gas into a roadmap for tuning
similar sensors to flag other dangerous or important chemicals.

The team’s framework is a new approach for optimizing the components — similar to those found in
flat-panel TVs — of a
liquid-crystal-based sensor: metal cations (which are positively charged ions), salt
anions, solvents, and molecules that form liquid crystals.

The research leveraged Mavrikakis’ computational chemistry expertise
and Abbott’s experimental expertise, cycling between quantum chemical modeling
and the laboratory experiments to optimize the sensor components for a targeted
substance. By tweaking the individual components in turn, they identified a
configuration that specifically responded to the molecule they wanted to sense,
called the analyte. This same approach could also yield new sensors for a host
of different analytes.

Looking to the future, such materials could be used to
indicate the freshness of fish or meat based on the presence of the molecule
cadaverine. Another variation could be used to
detect respiratory diseases based on analysis of small molecules, such as
nitric oxide in breath.

Consisting of a thin film of metal salt, the sensor material’s liquid crystals are anchored to the surface, all pointing in the same direction. The researchers
designed specific liquid crystal molecules and metal cations so that small
amounts of analyte would disrupt the interactions of the liquid crystals with
the surface, and throw the ordered arrangement into disarray. This is because
the change in the liquid crystal would be a visible indicator of the analyte’s

expensive explosive-detecting puffer machines in airports that rely on
complicated mass spectrometry or high-performance liquid chromatography
equipment, the liquid crystal sensors could be portable, wearable and

researchers plan to explore new combinations for additional analytes and
develop new liquid crystalline molecules, in combination with other metal salts
and solvents, to make more sensitive and selective sensors.

Source: Eureka