Inherently Safe Design

The first step to ensure an inherently safe design is to have an effective design control procedure. For this, you need to implement a well-established quality management system (QMS) right from the beginning. Your QMS shall be designed in line with the requirements of state-of-the-art standards such as ISO 13485, ISO 14971, FDA CFR Title 21 part 820.

Secondly, the design plan shall be effective and cover all design phases, such as the definition of inputs, outputs, design review, verification, validation and design transfer. All these require that you maintain detailed procedures. Only by implementing the tailor-made design control procedures, you can control the design of your device and ensure that specified design requirements are met. The list is not too long, but it can be a real challenge if you do not focus on each requirement in detail. Let’s dive into the design and development ocean.

The key factors leading to inherently safe design


First, you need to define and document the “intented  purpose” and “indications for use” of the proposed medical device. Indications for use are diseases or conditions that the proposed medical device will diagnose, prevent, cure or alleviate. “Intended purpose” is the device’s purpose – that is, what it will be designed to achieve.

Design planning

Like each product realization process, the heart of an effective design process is planning. It does not matter if you are after a simple medical device or starting the design of a high-tech complex structure. In each case, if we are talking about a medical device, the key route to safety starts at the planning stage. The design plan shall cover every bit of the product life cycle and reference activities like verification, validation, and design transfer which are appropriate at each design stage.

Design inputs

“Inputs relating to product requirements shall be determined and records maintained.” Maybe all of us have read this famous sentence of ISO 13485 many times. But are we aware how deep a short sentence like this can be? In order to ensure an inherently safe design, you need to define functional, performance, usability and safety requirements, according to the intended use, regulatory requirements, risk management outputs, compability with other devices. This must be done by an expert team and should benefit from outputs of effective risk management, which is performed in line with ISO 14971 and ISO/TR 24971 requirements. Additionally, inputs shall be defined according to output of the usability engineering process. Further details can be found on IEC 62366-1.

Design outputs

Technical drawings, device and material specifications, related test instructions which include clear acceptance criteria can be listed as an example for design outputs. These shall be filed in a form allowing traceability and be suitable for verification against the design and development inputs. Of course, similar to each design stage requirements, design inputs shall be approved prior to release.

Design review

The review stages shall be performed in accordance with design plan. The review shall concentrate on specific design outputs to confirm that the design inputs have been met. The records, which will be part of the DHF showing technical and regulatory compliance, shall include the participants involved, the date of the review and output of the review as a planned action. A detailed and well recorded design review will contribute a lot into an effective and successful design process. Therefore, it is important, that you include representatives of functions concerned with the design stage being reviewed, as well as other specialist personnel to your design review meetings.

Design verification

Successful verification reports are essential for an inherently safe design. The verification protocols including methods, acceptance criteria and as appropriate, statistical techniques with rationale for sample size shall be prepared. A so-called “traceability matrix” can be used to ensure that each design input covered by an appropriate design output.  In that sense, you can also reference verification reports within this matrix.

Design validation

The main difference of the design validation compared to design verification is that it should ensure that the resulting product can meet the requirements for the specified application or intended use. Therefore, design validation shall be conducted on representative product. Representative product includes initial production units, batches, or their equivalents. To ensure the intended use of the medical device, the validation protocol shall include clinical evaluations or performance evaluations of the medical device in accordance with applicable regulatory requirements.

Design transfer

After all verification and validation protocols have been implemented and reports which include results and evaluations of V&V activities have been issued successfully, the design transfer stage shall be initiated to ensure that inherently safe design is sustained during serial manufacturing. The main aim of this stage is to verify outputs for manufacturing before becoming final production specifications (DMR – Device Master Record) and that production capability can meet product requirements.

Control of design changes

The inherent safe design is a requirement throughout all life cycle of the medical device. The term life cycle covers all phases in the life of a medical device from the initial conception to decommissioning and disposal. Therefore, your design process shall also control the changes which could be required after the initial design has been validated. With the help of change control procedures, the legal manufacturer shall determine the significance of the change to function, performance, usability, safety of the medical device and applicable regulatory requirements for its intended use.

In addition to the design review requirements mentioned above, the review of design changes shall include evaluation of the effect of the changes on constituent parts, processes including the delivered medical devices. The inputs or outputs of risk management process shall also be reviewed.

Design files

The so-called Design History File (DHF) is the main objective evidence where the legal manufacturer proves the inherent safe design of a medical device. Therefore, DHF shall include or reference records generated to demonstrate conformity to the requirements for design and development and records for design and development changes.

We know how difficult planning all design requirements can be. Especially for start-ups, at the initial design phases, the long requirement list may result in endless discussions and become a real challenge. MEDLOFT experts can support you throughout all design stages.

Medloft experts can help you on defining the inputs, evaluation of risks related to the clinical hazards and validate your design by preparing an effective traceability matrix. Don’t forget, with effective risk management, which needs expert input, you can improve the usability of your device. You can contact MEDLOFT experts to establish a strong design process, which will reduce incidents and product recalls related to your medical device.