Form Study

Quite often in the course of designing a product, you'll find yourself doing some strange things. Although not the strangest thing one could do, creating this form study felt slightly bizarre, due to the unusual combination of materials and process. 

The aim was to "cut and shut" an existing collapsible silicone measuring cup into a form that more closely resembled our inhaler concept. Silicone is a notoriously hard material to adhere to anything, so after attempting to combine the parts with contact adhesive, it became apparent that glue wouldn't do.
It was decided that a mechanical fastening alternative was required, and so we decided to stitch the components together using dental floss (which was chosen for its strength and ribbon shape). The finished product, combined with some card, answers some of our most pertinent questions regarding;

• Ease of use
• Size
• Shape
• Tactility
• How the extended silicone volume translates when flattened

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  Stitching the mock up

  
  

  

  Collapsed

  
  

  

  Extended

  
  

  

  Rear 3/4

  
  

  

  Side Elevation - Extended

  
  

  

  Side Elevation - Collapsed

  
  

  

  Hand Grip

Inside an MDI canister

Arguably, the most important aspect of a Metered Dose Inhaler is the fact that it delivers (as the name implies) a metered dose. But how is it able to do this? We disassembled an empty canister to find out...

PS: Do not attempt this yourself. The canister is highly pressurised.

MDI Canister

Aside from the main aluminium body, the canister includes intricate plastic components to form a valve which temporarily stores the set amount of medicine (in powder form) before releasing it when activated. The aluminium cover is not pictured, due to the fact that it was destroyed beyond recognition in the process of disassembly.

Timing Doses

As previously mentioned, we've been investigating ways of informing the user of how long to hold their breath (usually 10 seconds). One of the more promising solutions appeared to be Thermochromic materials.

If used to form the nozzle of the inhaler, a thermochromic material could be tuned to instantly change colour when the medicine is sprayed, revert to its original colour after 10 seconds (depending on the ambient temperature). To determine the viability of their use, we conducted an experiment:

More Inspiration

From the outset of this project, one of the main priorities has been to design a way for users to correctly time their doses, ie one spray at a time, hold their breath for 10 seconds, and repeat after 1 minute if necessary.

Below is a collection of some of the sources we found for inspiration:

Cooking timer

Another cooking timer

Clockwork mechanism

Cooking Timers contain a (comparatively) simple clockwork mechanism, which causes rotation at a specific rate. This could theoretically be applied to the MDI design to prevent the user from dosing too quickly, although it is exceedingly complex, bulky, and possibly too fragile for any practical inclusion.

Another means of reminding the user to hold their breath could be a limitation on how often the inhaler resets itself before being able to be used again. One way of achieving this could be through the use of a viscous substance, such as grease or glycerine, in a hinge. This would create resistance when trying to reset the inhaler, making it take longer than expected. 

Glycerine

Of course, this solution also has its own obstacles such as maintenance, contamination, added complexity, etc. An air piston, like the ones used in some cassette players to artificially slow the opening of the door, would be a better solution, but is still a little too complex.

Ultimately, we selected yet another method for timing doses, which we'll reveal soon...

Inspiration

One of the main focus points of this design is to incorporate a collapsible spacer into the MDI. The ideation phase produced a plethora of ways to make this happen; although, one particular form kept recurring...

Bisected silicone measuring cup

Silicone measuring cup

Many commercially available products, such as travel mugs, measuring cups and colanders, utilise the flexibility of silicone to create collapsible shapes. This concept is well suited for use as a spacer, due to its robustness and portability.

Another source of plentiful inspiration was Origami. The "folding torque cylinder" and "magic ball" constructions are able to quickly transform from a usable cylinder into a flat shape, torus or ball. 

Folding Torque Cylinder

The Magic Ball in action:

Modelling MDI Spray

The spray ejected from a pressurised canister has the potential to influence a lot of aspects of the inhaler design; spacer shape, size, material, nozzle design, disassembly for cleaning, etc.

To quickly model the ejected particle behaviour of Salbutamol Sulfate (the medicine used in Ventolin inhalers), we designed a simple experiment;

MDI Spray Modelling

In this experiment, the inhaler is repeatedly sprayed directly at several sheets of paper (or panes of glass), with the distance between the inhaler and the sheet increasing by a set increment each time. This should provide several cross-sections of the ejected spray, which can then be used to gauge its overall shape.

Because Salbutamol Sulfate is a fine white powder, it is hard to identify on any surface except at very close ranges. We tested the spray on matte black, white and transparent surfaces with little success. So to try and isolate the spray from its corresponding surface, we shone an Ultraviolet light on it. Many white particles and surfaces fluoresce under UV light...

Inhaler residue on black, white and glass

Residue under UV light

Unfortunately, Salbutamol Sulfate is not one of them.

Experiments are a necessary component of the design process, and a negative result can still prove to be enlightening. This time, however, we had to search for alternative sources of information...

New Direction

Design is a dynamic process; the journey from problem to solution can go in any and all directions. One of the hardest parts of any ID project is being decisive as to which path to follow. For this project, we decided to move on from the initial vortex-driven MDI concept in favour of something a little more familiar and intuitive. The priorities for this direction are:

• An incorporated, collapsible spacer
• A means of encouraging correct technique
• A means of indicating the remaining doses
• Hygiene

We'll be posting some interesting content from the development (so far) soon!

Collapsible MDI Concepts

Basic mockup