Stabilization of SAW atomizer for a wearable olfactory display

An olfactory display, a gadget to generate odors and to deliver them to a user's nose, is being developed since it is expected to become useful in human interface. We developed an olfactory display using a surface acoustic wave (SAW) device and micropumps. It can atomize odorant liquid based on SAW streaming phenomenon. However, we found that atomization capability of the SAW atomizer deteriorated in a few tens of seconds after the start of driving the SAW atomizer. We hypothesized that SAW velocity change due temperature change of SAW device caused resonant frequency shift. Therefore, we constructed frequency correction system using a FPGA. We evaluated the system using a quartz crystal microbalance (QCM) gas sensor. In the experiment, the atomization capability was kept for longtime while SAW device driven with the frequency correction system whereas the atomization capability deteriorated in 15 seconds without the correction system. Thus, we concluded that the constructed system was useful and should be embedded into our wearable olfactory display.