The X-Factor – Medical Plastics News

The development of an intelligent medical device is a task between complicated and complex. Strict regulations and complex requirements require a wide range of skills from product design to manufacturing and processing to risk management. Peik-Christian Witte, Head of Engineering & Innovation, Sanner GmbH, explains how to develop intelligent products with Design for Excellence.

Smart medical devices with certain functions such as reminders or dosing can increase adherence to therapy. The product range extends from intelligent tablet dispensers to retrofittable add-ons for inhalers or injection systems.

Numerous factors are involved in the development and subsequent production of such products. Each factor has a different focus depending on the complexity and design of the device. In Design for Excellence (DfX), the X stands for a variable that makes a development successful only in optimal interaction with the others (Figure 1).

Design for product

Requirements management already plays an important role in the first development phase. Based on numerous customer requirements, product designers should develop concepts that take into account functionality, manufacturability and costs – also for subsequent series production – and physically implement the results in CAD models (Computer Aided Design).

Design for ease of use

Ease of use and ergonomics make a decisive contribution to the correct use and acceptance of the smart medical product, which ultimately improves the success of the therapy. Special attention must therefore be paid to usability with the aim of minimizing risks from application errors, ensuring patient safety and creating the framework for the highest possible adherence.

Design for manufacturing

The product must be optimally designed at an early stage with regard to the planned production and assembly conditions, quality and costs. Especially with plastic components, product and process development must go hand in hand, which is why material selection, tool and injection molding technology, the lowest possible number of components and functional integration are taken into account.

Version for assembly

The product design including the product structure has been optimized with regard to assembly. The assembly concept (ie a partially automated or a fully automated process) depends on the number of parts to be assembled.

Design inexpensively

An optimal cost-benefit ratio as well as low follow-up and conversion costs are also relevant. The considerations include the optimal use of materials, the smallest possible number of components and the optimization of the cycle times of the manufacturing process. Since electronic components for smart medical devices can also drive up manufacturing costs, these are also analyzed in detail.

Patient safety design

Patient protection, patient well-being and patient benefit are important issues in the development, production and use of intelligent medical products. Adverse results or harm from health interventions must be avoided, prevented and / or improved; B. by ensuring the correct use of the device through sensors that indicate incorrect handling.

Design to reduce risk

In order to ensure patient safety, risk management according to ISO 14971 is a central element in the development of intelligent medical products. Manufacturers must ensure that their products are safe when used properly and eliminate or minimize the risk of errors in handling the product.

Design for quality

Process reliability and speed play a major role in the development and implementation of test concepts. Precise, often fully automated error detection is essential. Today it can be implemented almost in real time using video assistance systems integrated into the production process. These systems compare the actual results with the specifications from the CAQ system (Computer Aided Quality Assurance).

Design for regulatory requirements

Smart medical devices are usually categorized as “active medical devices” and are subject to the same strict documentation requirements as all other medical devices. This includes risk analyzes and risk assessments to prove the safety and performance of a clinical assessment as well as comprehensive quality management, especially when using electronic assemblies.

Design for recycling

In the case of built-in electronic components, environmental aspects such as disposal, recycling, retrofitting and rechargeability play a central role in the development. Recycling considerations maximize the amount of recyclable and reusable materials; they also help to develop products that make it easier to break down and recycle valuable materials.

CASE STUDY Best Practice 1: Inhaler mouthpiece

A mouthpiece for a measuring device for determining inflammatory activity in chronic respiratory diseases shows how the aspects of Design for Excellence interact: Product and usability design ensure high functionality and user-friendliness. Design for Manufacturing and Assembly defined the multi-step assembly line, including filling, welding, and packaging (Figure 2).

The main challenges in assembly consisted of feeding the various parts and filling media in a product-friendly manner, of dosing them to an accuracy of 1/100 gram, and of correctly positioning and welding components and filter materials. The result is a multi-stage, precise and fast assembly with high reproducibility and quality.

In addition, a fully automatic, software-supported 100% check of every work step ensures quality control: 15 camera systems check presence, correct execution and completeness, while six weighing stations simultaneously check the adequate number of items. This combination eliminates the need for subsequent tests on the fully assembled part, which saves resources and saves time and money.

CASE STUDY Best Practice 2: Additional device for inhaler

Another example is an add-on device for a DPI (dry powder inhaler) [Figure 3]). First, the development team had to answer the following questions: Where and how can we position and attach the electronic components in order to guarantee their functionality and to make the assemblies reproducible for large quantities?

The position of the sensors is crucial: For example, one of the sensors ensures that the vibration properties are optimally transmitted when you inhale. This avoids overdosing or underdosing and helps maintain both ease of use and patient safety. The exact position of the sensor also prevents impairments that could arise from the user’s grip.

Special attention must also be paid to flexible tolerance compensation and the simplest possible tool geometries for fixing the sensor boards, which minimize subsequent cycle times. A pre-assembled battery with holder, which is placed in the base of the add-on, simplifies the assembly steps and cabling.

Years of experience

As the two examples show, smart medical devices must be designed to be ready for series production. These complex requirements can only be met by a team of engineers, project and quality managers and compliance experts who precisely coordinate all process steps in Design for Excellence and work together flexibly.

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