Sub-picowatt resolution calorimetry with a bi-material microcantilever sensor

We have designed and fabricated bi-material microcantilevers with low conductance by minimizing the width and thickness of the cantilevers while keeping them suitable for detection with an optical deflection technique. The conductance of a cantilever is determined experimentally to be 330 ± 20 nWK−1. Using this cantilever, we have measured less than 1 pW of heat flow through the cantilever. The thermal noise-limited resolution of the cantilever is expected to be ≈ 50 fW. Such cantilevers give us additional tools to probe thermal transport through nanostructures, especially through single molecules where picowatt-level sensitivity is necessary