Acoustic Subwavelength Imaging and Edge Detection for Resolution Enhancement

We developed a new acoustic imaging system to increase the imaging resolution. If the object contains fine details, for example, two scatters close to each other, only a blurred image can be obtained from conventional diffraction limited imaging systems. In this work is we design a transmitter/receiver pair. The transmitter is put close to the scattering objects, and the receiver is put close to the probe, so that the previously lost fine details can be resolved. We can get either the edge or the full detailed image. The transmitter and the receiver are fabricated by 3D printed resonator arrays and gratings. The size is scalable with respect to the working wavelength. The lenses shown in the figure has the lateral size of 20 cm and work for 9000 Hz.


Hydrogel based acoustic functional materials

Hydrogel has various good properties, such as soft, wet, bio-compatible, stretchable and easy to bond with different surfaces. Hydrogel also has almost the same properties as water.

Invisible underwater robot is constructed by hydrogel with embedded hollow channels for hydraulic actuation. The designed robot is both optically and acoustically invisible in water. Thus it can be used as shadow-free surgery tools.

Tunable acoustic impedance matching layer is designed by embedding periodic hollow channels inside hydrogel. By changing the filling materials and the filling ratios, the acoustic transmission and acoustic impedance can be tuned over orders of magnitudes in broad frequency ranges. The impedance matching layer we designed has the advantages such as tunable, broadband, soft, and biocompatible.

Dynamic imaging mask is important in advanced imaging functions such as compressive sensing and holography. Here we embed 2D unit cells in hydrogel sheet and control the filling material in each unit cell individually. The sound transmission through each unit cell is controlled by the filling material. In this way, we can modulate the image transfer function through the hydrogel sheet dynamically.