Olfactory Display with Silicon Based MEMS Vaporizers

In San Jose, Calif., POSIFA Microsystems Inc. is developing a smart olfactory display based on their proprietary technologies.

A visual display has usually meant a television or computer monitor, which provides movies or images to a human user. An olfactory display is an olfactory counterpart to a visual display, which provides olfactory stimuli instead of visual stimuli. With an olfactory display one day fairly soon, any user of a mobile phone, anywhere, will not only be able to receive a video and audio information, but also olfactory information like scents emitted from flowers, food and spices.

The display comprises a silicon based MEMS vaporizer, a Bluetooth CC2540, a button cell lithium battery, and a reservoir filled with a scented liquid.

Figure 1, Silicon based MEMS vaporize

Reference to Figure 1, the vaporizer is a micromachined silicon chip which consists of a thin membrane, at least a microchannel buried under the membrane, a resistive heater disposed on the membrane and aligned with the microchannel, a resistive temperature sensor disposed on the top of the heater with a thin insulation layer between them. The inlet of the microchannel is inserted into the reservoir. The scented liquid in the reservoir can be driven into the microchannel by the capillary action of the microchannel. When the heater is applied with a heating current the scented liquid under the heater will be vaporized. The vapor density and the vaporization time depend upon the applied heating current. The heating current is controlled by the Bluetooth microcontroller which can receive digital signal sent by a smart phone. So the vaporizer is actually controlled by the user of the smart phone.

The vaporizer works like a liquefied-gas thruster where propellant is stored in liquid phase, vaporized, expelled as a gas. Reference to Figure 2, it has been shown that an olfactory display should have three major roles: (1) to make scented air from the stocked form of odor material (vaporization), (2) to generate scented air with desired components and concentration by switching/blending multiple kinds of scents (blending), and (3) to transfer scented air to human olfactory organ (scent delivery). The vaporizer can combine all three major roles into a single process and therefore a complicated and bulky olfactory display system becomes a portable and wearable device.

Figure 2, Roles of an olfactory display: scent generation and scent delivery

The vaporizer is a MEMS actuator and fabricated using the technologies of microelectronics which provides with lower cost, lower power consumption, increased reliability, higher precision, small size, and compact structure. The Bluetooth CC2540 is not just a Bluetooth radio; it also features an 8051 processor that enables to run without external microcontroller.  Since the power consumption of the vaporizer is lower, the lithium battery can run enough long time without changing a new one.

Reference to Figure 3, Figure 4, and Figure 5, the olfactory display can be shaped like a portable perfume bottle or a wearable jewelry accessory such as pendant, waist, arm ornament, and so on. More special, the olfactory display can be simply incorporated into a smart phone as an accessory.

Figure 3, Perfume bottle with a silicon based MEMS vaporizer

  

Figure 4, Pendant with a silicon based MEMS vaporizer

FIG 5, Smart phone with a silicon based MEMS vaporizer module

As the vaporizers can be combined to comprise a total olfactory system, a variety of olfactory displays can be realized. Compared with several types of developed olfactory display, our system is much light and small. Since the developed olfactory display comprises of mass flow controllers, inkjet devices, solenoid valves, and fans, it is inevitable to form a larger instrument.  Our system is portable and wearable it can be attached to a smart phone or other portable electronic devices so that an internet carrying an extensive range of olfactory information becomes reality.