Helix Auto-Injector

The Circular Emergency

In my final year of university, we were encouraged to enter an external brief and communicate with relevant experts to form a rational project. I chose the RSA The Circular Emergency: Design a product, service or system that uses circular design principles to make emergency medical care more effective.


Current adrenaline auto-injectors are single-use devices and disposed of as hazardous waste. The design of some injectors is confusing for the user to determine the needle end. Dosage volumes and needle lengths are also inadequate.


The recent Pret a Manger tragedy has highlighted how dangerous an allergic reaction can be. I discovered there is a shortage of EpiPens, they’re confusing to use and non-recyclable. I started by designing a resettable mechanism using physical working prototypes and reducing the number of components. I discussed my project with a physicist, nurse and patients.


My design response is a user-friendly reusable auto-injector that incorporates a resettable mechanism and replaceable medication capsules. The product graphics explain how to operate and refill the device and make the needle end obvious. Helix accommodates everyone by offering three separate medication capsules following the NHS dosage guidelines.

Helix Medication

Helix accommodates everyone by offering three separate medication capsules following the NHS dosage guidelines. Paediatric doses of adrenaline: < 6 yrs - 150 micrograms (0.15ml of 1:1000), 6-12 yrs - 300 micrograms (0.3ml of 1:1000), > 12 yrs -500 micrograms (0.5ml of 1:1000).

Inside Out

The mechanism I designed works similarly to a spring-piston air rifle with the energy stored under a compressed spring. A combination of the case design and working mechanism allow the device to be reused endlessly. The Helix auto-injector model is made of only 8 parts including the snap-fit safety cap.


The Helix auto-injector and medication capsules will be used in the existing prescription service making it to convenient to introduce. The used capsule is received back by the medical services either by the paramedics collecting it at the scene or the user returning it to the pharmacy. Each part of the capsule is then separated for recycling.

In Action

The clear emergency instruction diagrams highlighted on the helix auto-injector inform the user to: remove trigger cap, push trigger against outer thigh, hold for 10 seconds, call 99, ask for an ambulance and says the word ‘Anaphylaxis’.

Working Prototype

I 3D printed each component and assembled it with appropriately sized metal springs. The model is larger than the final dimensions of the Helix case design due to material flexibility of the PLA. However, the application of the reusable mechanism can be applied to Helix when manufactured out of the proper materials in industry.