Reliably measuring transport diffusivities in nanoporous crystals presents a significant challenge ; doing so in a sensor is even more daunting. Conventional experiments rely on monitoring the transient uptake or release from the adsorbent following a sudden change in the adsorbate concentration (i.e., by moving between two points on an isotherm). In a VOC sensor surrounded by a fixed atmosphere to be analyzed, the non-equilibrium conditions required for measuring adsorption kinetics must be achieved differently. Since, for a given VOC concentration, the uptake in a nanoporous adsorbent is a function of temperature (Fig. ), a sudden temperature step also disrupts the equilibrium. For example, rapidly heating an adsorbent from to at a fixed analyte concentration triggers desorption until a new equilibrium uptake value is reached (Fig. ). When the temperature change is sufficiently rapid, the time constant of the desorption transient ( ) reflects the diffusivity of the analyte in the adsorbent at temperature . For a well-defined adsorbent geometry such as a MOF thin film, diffusivity values can then be extracted by fitting the desorption transient with a suitable model. Solving Fick's equation for one-sided diffusion of the analyte out of the sensor's adsorbent layer yields