Stress-Induced Chemical Detection Using Flexible Metal−Organic Frameworks

TLDR

The authors demonstrate stress‑induced chemical detection by integrating a thin HKUST‑1 MOF film onto a microcantilever surface. The microcantilever converts the energy of molecular adsorption into measurable mechanical deflection, enabling a highly responsive, reversible, and selective sensor. The sensor responds to water, methanol, and ethanol vapors (but not N2 or O2), with signal magnitude following a Langmuir isotherm; the MOF hydration state can be tuned for CO2 selectivity, and surface‑enhanced Raman spectroscopy was used to characterize the film, highlighting the versatility of MOFs for selective analyte detection.

Abstract

In this work we demonstrate the concept of stress-induced chemical detection using metal−organic frameworks (MOFs) by integrating a thin film of the MOF HKUST-1 with a microcantilever surface. The results show that the energy of molecular adsorption, which causes slight distortions in the MOF crystal structure, can be converted to mechanical energy to create a highly responsive, reversible, and selective sensor. This sensor responds to water, methanol, and ethanol vapors, but yields no response to either N2 or O2. The magnitude of the signal, which is measured by a built-in piezoresistor, is correlated with the concentration and can be fitted to a Langmuir isotherm. Furthermore, we show that the hydration state of the MOF layer can be used to impart selectivity to CO2. Finally, we report the first use of surface-enhanced Raman spectroscopy to characterize the structure of a MOF film. We conclude that the synthetic versatility of these nanoporous materials holds great promise for creating recognition chemistries to enable selective detection of a wide range of analytes.