Controllable optical transparency using an acoustic standing-wave device

• Light blocking particle suspensions were aligned to control the optical transparency of a device.
• Particles were aligned using an acoustic stimulus based on a standing-wave.
• Varying the frequency demonstrated the controllable transparency of the device.
• The alignment had a memory effect retaining the alignments for many minutes.

In this paper, a suspended-particle device with controllable light transmittance was developed based on acoustic stimuli. Using a glass compartment and carbon particle suspension in an organic solvent, the device responded to acoustic stimulation by alignment of particles. The alignment of light-absorbing carbon particles afforded an increase in light transmittance as high as 84.5% and was controllable based on the control of the frequency and amplitude of the acoustic waves. The device also demonstrated alignment memory rendering it energy-efficient.