High Resolution Near-Field Radiative Heat Transfer Measurements Using Nanomechanical Oscillators.

We report measurement of near-field radiative heat transfer using a new temperature-sensing approach based on nanomechanical oscillators. Silicon nitride membranes are used as sensors by tracking temperature-induced variations of their mechanical resonance frequency. We measure near-field radiative coupling by approaching a room-temperature SiN membrane in extreme proximity with a heated (ΔT=16.1 K) hemispherical BK7-glass surface of 12.7 mm radius. Measurement at distances ranging from 9 µm down to 1200 nm are reported, in good accordance with near-field thermal radiation simulations. Large distance measurements are enabled by the unparalleled temperature-sensing resolution of nanomechanical resonators—5 µK in the present case. The smallest achieved distance is most likely limited by surface contamination for these preliminary measurements.
In addition to high temperature resolution, this experimental platform has many potential advantages. For example, low dissipation mechanical oscillators could allow simultaneous characterization of near-field heat transfer and of Casimir forces. Additionally, techniques are widely available for coating SiN membranes with thin films or 2D materials, making it an ideal platform for testing new materials for near-field heat transfer.