Portable Smell Generators

Tu Xiang Zheng

A portable smell generator is proposed by the present author. The smell generator is constructed simply by using at least one MEMS vaporizer. The MEMS vaporizer converts an essential oil into its vapor. If the essential oil is a rose essential oil you will be reminded of a bouquet of beautiful flowers send to you by your friend. The smell generator may comprise a lot of MEMS vaporizers each of them converts a certain essential oil into its vapor. Then any favorable smell may be produced in accordance with the will of the people.

Actually, smells have been classified by a variety of methods, depending on the application. In the food industry, a convenient method is classification by the identity of the edible material of which they are reminiscent. The food smells have been grouped into caramel, honey, vanilla, citrus, and butter. In the cosmetic industry, smells are more likely classified by floral and herbal groupings, such as jasmine, rose, balsam, or pine. The smalls of the majority of foods and perfume can be produced by a combination of these primary smells, just as colors are produced by a combination of three primary colors. 

In order to do so all necessary essential oils need be produced. Essential oils are volatile and liquid smell compounds from natural sources, usually plants. Essential oils are prepared by fragrance extraction techniques such as distillation, pressing, or maceration. There are more than 90 essential oils, such as allspice essential oil, angelica essential oil, bay essential oil, benzoin essential oil, and  bergamot essential oil, each has its own health benefits. There also have synthetic fragrance oils which are primarily made from petrochemicals and attempt to duplicate the smell of a specific plant.    

The MEMS vaporizer is a silicon-based device.  It is fabricated using CMOS processing techniques and MEMS processing techniques. A MEMS vaporizer composes: a silicon substrate, a micro-channel array created in the silicon substrate, a membrane suspending, at least a resistance heater disposed on one the membrane, a resistance temperature sensor disposed on the membrane, two cavities are created in the silicon substrate, which all are integrated to form a vaporizer chip. A printed circuit board is for packaging the vaporizer chip and a reservoir is for inserting the printed circuit board with the vaporizer chip. An essential oil liquid is stored in the reservoir, and an air filter disposed on the top of the reservoir which allows air entering the reservoir and a same volume of the liquid in the reservoir entering the micro-channel array. 

In the operation, each of MEMS vaporizers is applied with a voltage and connected with a power field-effect transistor (FET). The power field-effect transistor functions as a switch for heating the vaporizer on demand. The temperature sensors are used to measure the temperatures of the essential oil entering the micro-channel and vaporizing respectively. A signals produced by the temperature sensors are amplified by a pre-amplifier and then send to a microcontroller for digital processing. After digital processing, the microcontroller will send a pulse-width modulation (PWM) to the gate of the power field-effect transistor which allows the voltage being applied to the vaporizer.

The portable smell generators can achieve small size, light weight, low power consumption, and low cost without sacrificing performance or features. Due to these advantages it become handy to carry it anywhere alongside. While it has some advantages in the smartphone and gaming market, it offers an attractive path of continued innovation especially for designers of wearables and smart clothing.