DEVELOPMENT DESIGN INPUT PROCESS

The following insight provides an overview of the 'Design Input Process' employed by D Squared during medical device development projects. This process is founded on the quality management and usability engineering principles defined in:

ISO 13485 – Medical Devices: Quality Management Systems – Requirements for Regulatory Purposes

IEC 62366 – Medical Devices: Application of Usability Engineering to Medical Devices

To demonstrate how the Design Input Process is applied in practice, this insight uses the example of a powered paediatric mobility system being developed for a user population spanning multiple age groups, physical abilities.

The device is intended to facilitate age-appropriate interaction, exploration, and participation in childhood activities and environments, while accommodating varying levels of assisted cognitive load. A key design objective is to support independent mobility and engagement without compromising the user's ongoing fine and gross motor development.

Use Specification

The 'Use Specification' (US) outlines the Medical Indications, Users, Use Environments, and Use Scenarios for the Medical Device that are used to define the scope of the Summative Usability study that will be conducted at the end of development to Validate that the chair meets the Design Inputs for the project.

User Requirements Specification

The ‘User Requirement Specification’ (URS) captures the ‘Mandatory’ and ‘Desirable’ requirements for the Users (patient, clinician, maintenance technician, etc.) along with functional, performance and safety requirements (according to the US), and applicable statutory regulatory requirements, directives, and standards.

User Requirements can be derived using the Users, Use Environments, and Use Scenarios defined in the Use Specification with examples shown below.

How to Derive User Requirements: Example A

 How to Derive User Requirements: Example B

We will now take a look at one of the User Requirements and see how this is used to derive multiple Product Design Requirements.

Product Requirements Specification

The ‘Product Requirement Specification’ (PRS) captures the ‘Mandatory’ and ‘Desirable’ product design requirements based on the URS. Multiple Product Requirements can be derived from a single User Requirement defined in the URS with examples shown below.

Mandatory & Desirable Requirements

Not all requirements defined in the URS and PRS are necessarily of equal priority and are normally divided into two categories (Mandatory & Desirable).

Validation & Verification Difference

Validation

Validation is the process of making sure that you have objective evidence that user needs (typically captured in the URS) are met for the Medical Conditions, Users, Use Environments, and Use Scenarios defined in the Use Specification. The objective of the validation is to make sure the user needs are met by a Medical Device that consistently provides the intended medical benefit in actual-use conditions. It is usually done though a series of Formative Usability Studies culminating in a Summative Usability Study which forms an important part of the regulatory submission for the Medical Device.

Verification

Verification is the process of making sure that you have objective evidence that specified requirements (typically captured in the PRS) are met. It is usually done by tests, inspections, and analysis, during the Design Verification Testing (DVT) phase of the project and forms an important part of the regulatory submission for the Medical Device.

Partnering with D Squared Product Development

Whether you are an entrepreneur looking for an original concept to develop, an established brand searching for custom industrial design solutions, or a local Liverpool business aiming to disrupt your sector, the journey from sketch to shelf requires a proven, repeatable framework.

By combining creative industrial design with disciplined mechanical engineering and the latest digital workflows, we help our clients minimize development risk, reduce prototyping costs, and launch highly successful products.

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