Enhancement Method of Surface Acoustic Wave-Atomizer Efficiency for Olfactory Display

This method can help answer key questions in human interface field. For example, many related to olfactory virtual reality. In our system, a micro-dispenser jets a few nano-liter droplets onto a surface.

Then a surface acoustic wave divides, atomizes that droplet to rapidly present a smell. Visual demonstration of this method is critical to show the optimization behavior. Prepare the surface acoustic wave device for the olfactory display.

This device has an interdigitated transducer, with reflectors on one end of a piezoelectric substrate. Additional details are in this schematic. The transducer region has 21 finger pairs.

The reflector has 32 finger pairs. The atomization area is depicted in blue. Prepare an amino-based silane coupling agent and put it aside.

Before silanization, clean the device with an acetone-soaked cotton swab. When done, take the device to a dip coater and attach it. Orient the device so that the atomization area will be immersed.

Next, place the silane coupling solution for use with the dip coater. Then, lower the device to immerse the atomization area. It is important to keep dipping speed slow and constant to obtain a uniform film coating.

Keep the device in the solution for five minutes. Raise the device out of the solution. Keep the device in the air for five minutes.

Next, remove the device from the dip coater, and rinse it in pure water for one minute. Then, turn the device to the dip coater with the same orientation. Remove the silanization agent from the dip coater.

Move on to prepare the amorphous Teflon material in solvent. Take the solution to the dip coater, and put it in position for use. Ensure the device is mounted to immerse the atomization area.

Once everything is ready, lower the device. Keep the atomization area in the solution for 15 seconds. Raise the device out of the solution.

Keep the device in the air for five minutes. Lower the device into the solution a second time, and wait 15 seconds. Then, raise the device, and leave it in the air for 30 minutes.

Next, remove the device from the dip coater. Place it on a hot plate at 180 degrees Celsius to bake for 60 minutes. Prepare the SAW device for the experiment.

Mount it on an aluminum-printed circuit board, using aluminum foil and conductive paste. Next, mount the circuit board with the device onto a platform. Connect the device to an RF power amplifier, driven by a function generator.

Set the wave form of the RF burst signal to be a sin-wave with a duty cycle of 10 percent. Set the wave frequency to the surface acoustic wave device oscillation frequency. Next, connect a burst square wave generator to allow a 24-volt pulse signal to a solenoid valve used as a micro-dispenser.

Set up a micro air pump to drive fluid from a reservoir to the micro dispenser. Use an air pump to guarantee the micro dispenser is filled with liquid for optimization. Move on to studying atomization with the device.

Put liquid into a vial and place it in the set-up. Air will enter the vial through the action of the micro air pump. The fluid from the vial will go to the solenoid valve.

The valve is set up to dispense liquid on the atomization area of the device. Set the wave form of the pulse signal applied to the solenoid valve. Use the function generator to set a square wave pulse sequence, with a 10 percent duty cycle.

Observe the surface of the device. Over time, the pulse sequence will form a large droplet for atomization. Apply the RF burst signal to the device for as long as needed to atomize the droplet.

Observe the surface of the device, to witness atomization, and to inspect the remaining liquid droplet. Once the system is ready, recruit a person to detect scents. Have the person sit with his nose 20 to 30 centimeters in front of the atomization area.

Adjust the height of the atomizer to level of the participant's nose. Dispense the liquid onto the device and atomize it. Allow the participant to detect the scent.

In this top view of a bare lithium niobate surface, one microliter of ethanol has spread to a thin film. In contrast, this side view of a coated device surface demonstrates the formation of a droplet. This is a microliter droplet of water on a bare surface.

It eventually spread into a thin film. A microliter droplet of water on a coated surface persisted. In this sequence, a thin film of lavender is atomized on an uncoated surface.

Strong atomization occurs at the center of the liquid, but not at the edge. In the end part of the liquid remains. A similar sequence for a lavender drop, formed on a coated surface, shows a concentrated mist during atomization.

In comparison with the uncoated surface, after atomization, much less liquid was left in a smaller area. The liquid droplet on amorphous Teflon surface is almost completely atomized, indicating enhanced atomization efficiency compared with an uncoated device. Fewer droplets are left behind due to improvements in efficiency, which helps resolve smell persistence problems in virtual environment olfactory displays.

Although this is a fundamental technology to realize olfactory virtual reality, a variety of other appreciations can be emerging.