Article,
Observation of a chemical reaction using a micromechanical sensor
Chemical Physics Letters, 217 (5-6): 589 - 594 (1994)
DOI: DOI: 10.1016/0009-2614(93)E1419-H
Abstract
We describe a new form of calorimeter designed for use in gaseous
and vacuum environments which can sense chemical reactions with an
estimated sensitivity limit of approximate 1 pJ. The device is
based on a micromechanical Si lever coated with a thick layer of
Al upon which a sample in the form of a thin layer is fixed or deposited.
Heat fluxes are detected by measuring the cantilever deflection induced
by the differential thermal expansion of the lever (bimetallic effect)
using the optical position sensor from a force microscope. The limit
of sensitivity to local temperature changes is approximate 10-5
K at 300 K. Using this technique the catalytic conversion of H2 +
O2 to form H2O over a thin Pt overcoated layer is observed to exhibit
self-sustained oscillations in the reaction rate on the macroscopic
scale.
