Staying flexible

Osaka, Japan – Scientists from the Institute of Scientific and Industrial Research (SANKEN) at Osaka University, in collaboration with Chuo University, Eindhoven University of Technology, and National Institute of Advanced Industrial Science and Technology, have developed a non-disruptive sheet sensor for liquid quality monitoring. Using voltages generated in a carbon nanotube layer, the method does not require sampling, chemical labels, or an external light source. The application of this research may enable the on-site quality control of chemical factories or environmentally sensitive water sites.

The monitoring of the chemical content in the water flowing through pipes is critical for industrial applications, such as food or beverage production, as well as for identifying environmental contamination in the effluent that reaches the environment. However, current methods require the periodic collection of samples for testing, as well as the use of chemical reagents or labels. A new approach is needed for non-disruptive continuous monitoring.

Now, a team of researchers has invented a flexible sheet that uses an embedded carbon nanotube film as a photodetector layer. When exposed to light radiation, the carbon nanotubes can produce an electric voltage, which can be detected by attached electrodes. “Our stretchable sheet device is equipped with a high-sensitivity, broadband optical sensor, which enables it to be attached to a wide variety of pipe shapes,” authors Li Kou and Teppei Araki say.

Changes in water temperature could also be monitored passively based on blackbody radiation. For impurity detection or beverage inspection, an external terahertz or infrared light source may be used. This allows spectroscopy methods to be applied continuously to flowing liquids. “The optical sensor sheet can easily visualize the concentration, temperature, viscosity, and location of cracks and liquids in pipes, contributing to the realization of future environmental measurement systems,” say senior authors Yukio Kawano and Tsuyoshi Sekitani. The researchers tested the system and found a linear response between glucose concentration and passively generated voltage.

The team hopes that this research can lead to the modernization of industrial quality control methods, in which contaminant concentrations can be monitored continuously, rather than during scheduled collections.

###

The article, “Stretchable broadband photo-sensor sheets for nonsampling, source-free, and label-free chemical monitoring by simple deformable wrapping” was published in Science Advances at DOI: https://doi.org/10.1126/sciadv.abm4349

About Osaka University

Osaka University was founded in 1931 as one of the seven imperial universities of Japan and is now one of Japan's leading comprehensive universities with a broad disciplinary spectrum. This strength is coupled with a singular drive for innovation that extends throughout the scientific process, from fundamental research to the creation of applied technology with positive economic impacts. Its commitment to innovation has been recognized in Japan and around the world, being named Japan's most innovative university in 2015 (Reuters 2015 Top 100) and one of the most innovative institutions in the world in 2017 (Innovative Universities and the Nature Index Innovation 2017). Now, Osaka University is leveraging its role as a Designated National University Corporation selected by the Ministry of Education, Culture, Sports, Science and Technology to contribute to innovation for human welfare, sustainable development of society, and social transformation.

Website: https://resou.osaka-u.ac.jp/en