Scent Delivery 1: Mechanics

Localised smell distribution or ‘scent delivery’ is the tough technical nut to crack on this project. There are two aspects to this:

> Mechanical: dispersing scent - at the right concentration - into a localized area quickly/reliably and in a cost-effective way.

> Creative: dispersing it in a way that allows us to create meaning rather than just, well, smell.

Mechanically, there are a number of ways to deliver scent in a controllable way, from the ultra low-tech to very sophisticated. Initially some low-tech devices will be OK to start prototyping the experience but ultimately we’re going to need something more sophisticated that can operate remotely and automatically because we’d like to do some sort of field trial.

1. Scent strips

These are the things you use at perfume counters and we used to demonstrate scents at the first work-in-progress meeting. Cheap, reliable but relies on the user wanting to actually pick it up. Also, you need to know how to use them – for instance if you actually touch your nose with the scent strip it can immediately nuke your sense of smell because you risk transferring some of the scent to your skin. This evaporates and interferes with subsequent scents.

2. Atomisers

Can be used with scents dissolved in alcohol. Effective but not very controllable and deliver large droplets of liquid which leave a residue and can be objectionable. A bit of a blunt instrument.

3. Nebulization

Pure fragrance oil in its liquid form is run through a venturi device that disperses the oil into extremely fine particles in the air. These particles are 100 times smaller than what comes from an atomiser and hang around longer before they dissolve without sticking to carpets, wall coverings or users themselves.

4. Dry air scent dispersion

Fragrance oil is embedded in a gel, in small plastic beads or in another scent-saturated substance and air is run over or through the substance, picking up the scent and delivering it via a small blower or a fan. This method is very efficient and can be limited to the immediate environment.

5. Ionization

A sophisticated and technically complicated way to break the oil into small particles by applying high voltage.

6. Microencapsulation

Mainly used to make a scent printable. Fragrance molecules are wrapped into a substance (encapsulated) that breaks when a certain pressure or friction is applied. The best examples are the ScentStrips® used in magazines.

Having looked at the relative cost/complexity/usability of all these methods we think that dry air scent dispersion is likely to be the most useful for a field trial. The units are reasonably cheap and some even include built in PIR sensors to detect proximity. The main problem is going to be that they used sealed capsules so we’re going to have to find a way to hack these and get our own smells into them in a re-usable way. I’ve set up a meeting with a UK-based manufacturer to talk to them about letting us have some units and technical assistance. Fingers crossed.