Human Factors Engineering (HFE), or usability engineering, focuses on the interactions between people and devices and ultimately, aims to enhance patient safety by minimising use-related hazards.

It is no longer appropriate to determine a mistake a user makes while interacting with a device as ‘user error’. These ‘mistakes’ or ‘user errors’ that occur during use of a device must be regarded as a fault in the device itself and subsequently, dealt with measures such as those a component failure would.


The wider benefits of reducing risks and enhancing patient safety include;

  • Devices that are easier to use (including easier to read controls and displays)
  • Safer devices
  • Better user understanding of the device and treatment
  • Device’s that are easier to maintain and repair
  • More intuitive device’s therefore reduced user reliance on manuals and reduced need for training / retraining
  • Reduced risk of use error
  • Reduced risk of adverse events therefore reduced risk of product recalls
  • Improved medication adherence
  • Wider inclusivity

According to researchers at Johns Hopkins University, in 2019, medical error was the third leading cause of death in the United States. Only lung disease and cancer took more lives that year. Of the deaths caused by medical error, it is estimated that 15% were a result of user error caused by a poorly designed user interface. To put this into context, in the US in 2019, a poorly designed user interface was responsible for more deaths than firearms.

How do we, as medical device designers, address the above problem and reduce risk too?

It’s crucial to understand the ways in which people (users) perceive and interpret information to make decisions about what to do and how to manipulate a device (this can include adjusting settings, replacing components, starting or, stopping the device). In turn, it’s important to understand how the device receives inputs from the user and consequently, responds.

We follow a standardised user-centred design process that focuses on user safety. This process is known as Human Factors Engineering or Usability Engineering and is mandatory when developing a medical device. The process is governed by the collateral standard IEC 62366, “Application of usability engineering to medical devices,” (or in the US by the FDA’s guidance documents, “Applying Human Factors and Usability Engineering to Medical Devices.” which are closely aligned to IEC 62366). IEC 62366 outlines a process of iteratively designing and testing a user interface to ensure user safety, and then validating the interface to ensure that no unacceptable risks arise from use. The user interface includes all components that the user interacts with while preparing the device, using the device and also maintaining the device. These steps typically include unpacking, setting up, calibrating, cleaning, perhaps replacing the battery and making general repairs to the device etc.


To comply with standards such as ISO 14971, it’s crucial to demonstrate that you’ve applied a number of tools to analyse and mitigate risk. There are a number of methods for identifying failure modes throughout the device development process such as FTA (Fault Tree Analysis) and FMEA (Design Failure Mode and Effect Analysis). Although there are other risk assessment techniques that are wholly acceptable such as HAZOP (Hazard and Operability Analysis), FMEA and FTA are industry favourites.

Human Factors Engineering fits into the Design Controls process, a process that gives structure to Medical Device Design & Development. Whilst Design Controls allows for some innovation in the design process, they ensure you are meeting all of the product’s and user’s indented needs in a tightly controlled manner. This ensures designs remain feasible and allow for full traceability. Ultimately, Design Controls demonstrate that your medical device is safe, effective, and meets the indications for use. Not to forget that they also focus on ensuring that you will be able to repeatedly manufacture the device as intended.

Applying Design Controls is not a singular activity. It is an accumulation of thorough planning, executing, and documenting throughout the process (pre-design control and during design control). Usually, Design Controls will start with capturing user needs to define Intended Use Statements/Claims. These claims, are then used to define the project’s design inputs which guide the design process and, ultimately, generate design outputs (examples of these include drawings, specifications & instructions – essentially everything you need to manufacture and assemble the device correctly) which address all user needs.

The Usability Engineering process is truly multi-disciplinary and relies on expertise from an array of disciplines such as engineering, design, cognitive psychology, and risk management. At HD, we benefit from the multi-disciplinarily of our team, and network, to offer a robust Human Factors Engineering element when designing medical devices. If you would like to learn more or discuss how Haughton Design can help with your Medical Device development, please get in touch.

Amber Davies, Human Centred Designer & Digital Marketer Amber Davies 30 July 2021


Get in Touch with Amber Davies

Human Centred Designer & Digital Marketer

Amber graduated from Cardiff Metropolitan University with a degree in Product Design. She has a particular interest in the medical field stemming from her personal experience of using a medical device. She pairs her design background with her personal experiences to apply empathy and develop improved user experiences. Amber also combines this understanding to liaise with customers and create digital content at HD.

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