Abstract
Acoustic waves, capable of transmitting through optically opaque objects, have been widely used in biomedical imaging, industrial sensing and particle manipulation. High-fidelity wave front shaping is essential to further improve performance in these applications. An acoustic analog to the successful spatial light modulator (SLM) in optics would be highly desirable. To date there have been no techniques shown that provide effective and dynamic modulation of a sound wave and which also support scale-up to a high number of individually addressable pixels. In the present study, we introduce a dynamic spatial ultrasound modulator (SUM), which dynamically reshapes incident plane waves into complex acoustic images. Its transmission function is set with a digitally generated pattern of microbubbles controlled by a complementary metal–oxide–semiconductor (CMOS) chip, which results in a binary amplitude acoustic hologram. We employ this device to project sequentially changing acoustic images and demonstrate the first dynamic parallel assembly of microparticles using a SUM.
Highlights
Acoustic waves, capable of transmitting through optically opaque objects, have been widely used in biomedical imaging, industrial sensing and particle manipulation
Acoustic waves possess no polarization and show no or little dispersion from the low audible kHz to the very high MHz ultrasound frequencies[7], which considerably complicates the realization of a spatial modulator for sound waves analogous to an spatial light modulator (SLM)
Controlling dispersion could efficiently modulate the phase of an ultrasound wave, but no suitable material or meta-material concept has been found to date
Summary
Capable of transmitting through optically opaque objects, have been widely used in biomedical imaging, industrial sensing and particle manipulation. Its transmission function is set with a digitally generated pattern of microbubbles controlled by a complementary metal–oxide–semiconductor (CMOS) chip, which results in a binary amplitude acoustic hologram We employ this device to project sequentially changing acoustic images and demonstrate the first dynamic parallel assembly of microparticles using a SUM. The large wavelengths of audible acoustic waves relative to the region of interest result in a differently scaled problem with low degrees of freedom, where a small number of larger actuators is sufficient This is contrary to the previously mentioned applications of highfrequency ultrasound, which benefit from large numbers of much smaller pixels. Having the sound wave generation and the shaping of the wave in the same device increases the complexity and limits the development of high-power devices with many degrees of freedom
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