Dithienylethene-Based Single Molecular Photothermal Linear Actuator

By employing a mechanically controllable break junction technique, we have realized an ideal single molecular linear actuator based on dithienylethene (DTE) based molecular architecture, which undergoes reversible photothermal isomerization when subjected to UV irradiation under ambient conditions. As a result, open form (compressed, UV OFF) and closed form (elongated, UV ON) of dithienylethene-based molecular junctions are achieved. Interestingly, the mechanical actuation is achieved without changing the conductance of the molecular junction around the Fermi level over several cycles, which is an essential property required for an ideal single molecular actuator. Our study demonstrates a unique example of achieving a perfect balance between tunneling width and barrier height change upon photothermal isomerization, resulting in no change in conductance but a change in the molecular length, which results in mechanical actuation at the single molecular level.     

QCM sensor array for monitoring terpene emissions from odoriferous plants

Abstract  An e-nose comprised of six sensing channels each coated with a molecularly imprinted polymer (MIP) selectively interacting with alpha-pinene, thymol, estragol, linalool, and camphor, respectively, was designed. When applying it for continuous online surveillance of terpenes emitted from basil and peppermint leaves as a criterion of freshness, it very appreciably reproduced the emanation patterns from these plants as shown by GC-MS. Chromatography yielded a variety of terpenes in a concentration range below 70 ppm. Trend lines obtained from the e-nose were corroborated by GC-MS and also appreciably fit the usual conduct of these plants as observable by the human nose. Graphical abstract        

Chemosensors in environmental monitoring: challenges in ruggedness and selectivity

Environmental analysis is a potential key application for chemical sensors owing to their inherent ability to detect analytes on-line and in real time in distributed systems. Operating a chemosensor in a natural environment poses substantial challenges in terms of ruggedness, long-term stability and calibration. This article highlights current trends of achieving both the necessary selectivity and ruggedness: one way is deploying sensor arrays consisting of robust broadband sensors and extracting information via chemometrics. If using only a single sensor is desired, molecularly imprinted polymers offer a straightforward way for designing artificial recognition materials. Molecularly imprinted polymers can be utilized in real-life environments, such as water and air, aiming at detecting analytes ranging from small molecules to entire cells. Figure       

Sensor strategies for microorganism detection--from physical principles to imprinting procedures

Detecting cells and microorganisms in different matrices is becoming an increasingly important task in a variety of fields including bioprocess control, food technology, health care, and environmental analysis. In this review, fast on-line detection methods for this purpose are presented including different recognition and transducer strategies.