A kinetic isotope effect is observed in the guest-induced bending curves of poly-4-vinylpyridine-coated microcantilevers. Protiated (nondeuterated) and deuterated isotopologues of ethanol, water, and acetone exhibit a clear difference in their time dependent bending response patterns. While most protiated species exhibit Langmuir-type absorption bending curves, the bending curves of deuterated species are characterized by a clear overshoot. Time-dependent Fourier-transform infrared measurements provide further insight into the interrelation between molecular level interactions and macroscopic mechanical bending. A model is suggested to interpret these observations.

A novel Porous-Silicon-Over-Silicon (PSOS) chemomechanical microcantilever sensor for the isotope discrimination of gas phase substances is presented. A strong isotope effect is observed in the guest induced PSOS microcantilever bending curves of novel poly-4vinylpyridine (P4VP) coated microcantilevers. Isotopologues of ethanol and water exhibit a clear difference in their time dependent bending response patterns. While the sorption of protiated isotopologues exhibits Langmuir-type sorption curves, deuterated isotopologues exhibit anomalous bending overshoot curves.

No abstract

The impressive developments in micro / nano-electro-mechanical-systems (MEMS; NEMS) have led to a new class of chemical and biological sensors based on micro and nano cantilevers. This work focuses on fabrication challenges of flat cantilevers exhibiting well-controlled, uniform and reproducible mechanical performance. Our experimental study is based on cantilevers made of crystalline silicon (c-Si), using SOI wafers as the starting material and using bulk micromachining. Experimental results on fabrication and characterization of composite porous silicon-crystalline silicon microcantilevers made of SOI wafers are also presented, where the porous silicon surface provides an excellent interface for immobilization of the biosensing layer. The optimal geometric design of microcantilevers depending on the application as well on the selected sensing mode (static or dynamic) is considered. The innovative aspects and open issues of NEMS/MEMS cantilever-based biosensors are addressed

Alkylating agents are reactive, often simple, molecules that are frequently used in diverse fields such as medicine, agriculture, and organic synthesis. For over a century, some highly reactive alkylating agents are also being used as blister chemical warfare agents. The detection and identification of such alkylating agents is not a simple task because of their high reactivity and often simple structure. Here we report on a new approach for the detection and identification of such alkylating agents using a simple luminescence based array sensor that mimics the olfactory system. In order to demonstrate the potential of the approach, seven π‐conjugated oligomers and polymers bearing nucleophilic pyridine groups, 1‐7, were adsorbed onto a solid support and exposed to vapors of alkylators 8‐15. Applying principal component analysis to the alkylation induced color shift patterns of the seven‐spot array results with a clear discrimination of the different alkylators. The comparison of the data obtained from the sensor array with known response patterns allows the clear identification of the specific alkylator. The spots are sensitive to minute concentrations of alkylators and since the detection is based on the formation of new covalent bonds these spots saturate, within seconds even at about 50 ppb. Copyright © 2010 John Wiley & Sons, Ltd.