Acoustic sensing and actuation is widely used in daily life applications. Yet, its application at the nanoscale has remained a major challenge. This has motivated Gerard to conduct research on nanoscale acoustics in atomic force microscopes for imaging purposes and graphene-based electromechanical systems for sensing purposes as well as for fundamental properties of two-dimensional materials. Gerard studies the propagation of sound waves at the nanoscale through nano-devices in order to understand the wave front arriving at the surface of the device and detects these with an atomic force microscope. Gerard was the first to quantitatively determine the physical contrast mechanism in such measurements, which requires detailed understanding of the nonlinear tip-sample interaction, the resonance frequencies of the cantilever, and the indirect ultrasound pick up. The key objective was to resolve the inner structure from the device in a similar way to conventional ultrasound imaging. Later on, Gerard studied the response of graphene to bulk acoustic waves and strain, as graphene has excellent mechanical properties for the application in acoustic sensors and actuators. Gerard was the first to show that graphene resonators can detect acoustic waves traveling through the substrate. In the future, Gerard plans to use his knowledge on these topics to develop new acoustic imaging techniques at the nanoscale as well as acoustic sensing techniques employing nanoscale two-dimensional materials at various length scales. Currently, Gerard is involved in the Plantenna project, a 4TU initiative, to study the application of ultrasound in agriculture and to develop autonomous sensor networks.