aflo™ - Medical Device Product Design

Research has shown that 86% of patients use their inhalers incorrectly. Respiratory Analytics is a start-up medical device company who have been developing aflo™, which is an automated training device and digital platform for patients with respiratory conditions such as asthma. The company’s hardware works with a user’s phone to guide them through the use of their inhaler and provides insight on their performance. The device is intended to assist in guiding the correct inhaler technique to improve symptom control in asthma patients.


The team at i4 Product Design was initially approached by the company’s founder after a recommendation from a fellow entrepreneur. After initially being contracted to support the development of a proof-of-concept version of the device for an Innovate UK project, i4PD was then engaged to develop aflo™ to the point of manufacture and certification. Specifically, i4PD was tasked with the hardware, mechanical, firmware and associated regulatory support. As the device was to be connected to a user’s phone a digital product design consultancy was also part of the development team.


Asthma inhalers are often used with a “spacer”: this is a small chamber into which the inhaler medication is dispensed, and the user then inhales from this chamber. This can make medication delivery more efficient. However the user still needs to inhale with the appropriate technique to get the maximum benefit.

The aflo device is fitted between a metered dose inhaler and spacer and automatically detects the key elements of correct inhaler technique such as shake duration, inhaler dispense timing, strength and volume of inhalation. Using a combination of real time LED indicators on the device and automatic messaging on the app, the user is guided through all of the correct steps of inhaler technique.

"We came to i4PD at the end of 2020 with some very rough drawings, big ideas and a modest budget, wanting to build a respiratory management tool to improve inhaler technique. Fast forward to 2023 - and via a second phase of product development - and we have a beautiful device, built to solve a major clinical problem, incorporating the best electronics, industrial and human centred design principles, delivering more functionality than we could have hoped for."

Susan Kelly, Founder and CEO.

The core of the electronics is a module which incorporates a Nordic nRF52833 processor core and Bluetooth LE radio, along with an on-board antenna. The software was written in C using Nordic’s nRF SDK.

i4PD have helped react to the volatility in the electronics component market and also unexpected obsolescence (due to the merger of two electronics manufacturers) by sourcing alternative components, testing and characterising alternatives, and writing flexible software that can support the alternative components with minimal changes.

Bluetooth LE wasto allow the device to communicate with the user’s phone, where an App captures the data and passes it to a database backend.

Mechanically the device needed to be compatible with a range of different inhalers and spacers, and needs to be small and light enough to be added to the inhaler / spacer without making it awkward to use. The controls and indicators needed to be accessible and visible when in use. The device needed to be cleanable and well-protected against splashing with water.  The final design uses a soft interface moulding which accommodates the inhaler and spacer, and can be removed for cleaning. A sliding guard holds the interface firmly in place and also prevents the device being used while it is on charge.


At time of publishing this case study the aflo system was undergoing the final stages of certification prior to CE marking. The product had passed stringent reviews from the test houses to achieve the goal of complying with medical device standards. Perhaps most importantly, the device is accessible from a cost perspective and, with the help of our co-design practices, a UX perspective. Based on the findings in Respiratory Analytic's studies it was clear how the vast majority of people using an inhaler could benefit from improving their technique with use of the aflo system.

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