Atomization of Viscous Fluids for Digital Scent Technology Using An Integrated Micro-droplet Generation Platform

Our team will develop a novel wearable digital scent-generation device for applications inenhancing Virtually Reality user experience. Currently, no widely-accepted technology toreliably and accurately dispense smell on-demand exists, especially for wearable devices. Wewill usemicroelectromechanical systems(MEMS) technologies to fabricate arrays ofmicroheaters and nozzle orifices to realize a wearableviscous fluid atomization platformfordigital scent generation. An important feature of this atomization platform is its ability toproduce 10µm(or smaller diameter) fluid droplets as mist, because droplets larger than 10µmare less likely to be absorbed by the olfactory tissues. The device could also release multiplescents to enhance the users’ experience by activating their sense ofsmell. One of our ultimategoals for this device is to integrate it with ECG (electrocardiography), EEG(electroencephalogram), and skin conductance sensors to quantify emotional changes such asheart rate variation, relaxation, and stress when different scents are activated.Currently, the most prevalent portable atomizers are based on using lead-zirconium-titanate (PZT)as a high-frequency piezo-actuator to generate small fluidic droplets. A major drawback of thistechnology is that lead is a harmful material that can damage the nervous system and cause braindisorders, particularly in young children. The fine particles generated by PZT-based technologymay be contaminated and are thus not suitable for daily life applications. Furthermore, commonpiezoelectric atomizers such as ultrasonic nebulizers are unable to aerosolizeviscousfluids,whereas jet atomizers are inefficient and inconvenient because they require compressed air. Ourteam has already demonstrated the feasibility of a lead-free atomizer to atomize fluids withviscosity about 200 times greater than water. Based on that platform, we will demonstrate asilicon-based viscous fluid atomizer for on-demand generation of droplets that can be efficientlyabsorbed by olfactory tissues in this project. There are several critical engineering challengesand scientific issues that will be addressed in this project in order to realize a small footprint andreliable viscous fluid atomizer: 1) enhancement of capillary flow rate in the atomizer’s chambersby controlling fluid viscosity via temperature; 2) determination of optimal ejection duty cycle toensure long-term operability of the atomizer without significant reduction in droplet ejectiontime response; 3) optimal chamber geometric design to control the size of bubble nucleation inorder to ensure stable mode of droplet ejection. Details of our methodologies to address theseissues are discussed in the proposal.