Developing Custom Filters for Medical Devices

Custom filtration solutions can enhance system efficiency, reduce costs, optimize filter lifetime, simplify filter change outs, and prevent incorrect filter installation.  

You might be asking yourself: What does customization MEAN in the context of filter design? In the table below, we’ll give a couple examples of standard vs. custom for various aspects of a filter, along with an explanation of how using a customized option can benefit your device.   

Customization can also address design challenges such as miniaturization and unique geometries. Now that you have a better understanding of what a custom filter is and the value it can bring, let’s discuss how to get started with the design process.

Start by defining the filter's purpose and the operating conditions. The filter’s purpose includes the functionality, the feed (what’s being filtered), and any regulatory requirements the filter must meet. The operating conditions include the temperature, the pressure and flow rates, and the sterilization requirements. 

For applications with moderate functional requirements and operating conditions,  off-the-shelf filters may provide sufficient functionality. However, when a filter needs to withstand specific and/or heightened demands for pressure drop, flow rate, operating pressure, and/or cycles of operation, a custom filter might be your best option. 

Once you have the foundation in place, our experts can guide you through your options for filter material/s, configuration, connectivity (inlet/outlet fittings), and performance testing. 

The answer to each of these questions will influence the material selection for your device. 

For most medical device applications, hydrophilic material will be best-suited for liquid filtration and hydrophobic material will be best-suited for gas/venting applications. 

Depending on the performance requirements of your application, you may need to consider a multi-layer filter. The engineering team at Saint-Gobain can optimize layering of filter materials to achieve three main goals:

• Filter Lifetime (e.g., extended or optimized to a particular timepoint)
• Multi-stage Filtration 
• Multi-functional Filtration

There are three main types of filter configurations: discs, cartridges, and capsules. When determining which configuration is best suited for your device/application, you’ll want to consider the effective filtration area (EFA) and the size/shape. 

• The EFA represents the total area of filter material exposed to the flow of liquid or air; EFA is a critical parameter because it can impact flow rate, dirt-holding capacity / service life, and filtration process efficiency. Your selection of filter material/s can impact the EFA required for your application.  
• The size and shape of the filter determine how it’s going to fit into your device. The way a filter fits into your device can impact human factors and usability for both standard operation and preventative maintenance. 

After you determine an appropriate EFA, selecting the filter configuration becomes easier.

Once you know the filter configuration, the next step is determining the appropriate inlet/outlet fittings. 

Prioritize the reliability of connections, and the ease of installation, with the unparalleled selection of inlet/outlet fittings offered by Saint-Gobain. Our fittings can be grouped into categories of hose barb, luer, threaded, quick connects, push to connect, tri-clamp… and, of course, customer-specific custom fittings. 

There are several potential advantages associated with incorporating customized fittings at the inlet/outlet of your filter:

Utilizing a different fitting at the inlet and outlet (e.g., male luer inlet and female luer outlet) can create a poka-yoke to prevent incorrect installation (wrong orientation, wrong location, etc.). Valved fittings can mitigate the loss of a valuable solution during filter change outs; valved fittings can also serve to protect end-users from exposure to caustic solvents during preventative maintenance. Quick connect fittings can improve ease of use and/or ease of filter change outs. Selecting fittings that seamlessly integrate into your device eliminates the need for complex and costly adapters; fewer adapters also mean less risk of leaks which can impact asepsis/sterility.   Customer-specific fittings can serve to protect OEMs from aftermarket competitors.

With over 40 standard options available, and the ability to customize, you should have no problem selecting the inlet/outlet fittings best suited for your application. 

Once you have the configuration and the inlet/outlet fittings, the next step is to define the filtration material/s. 

Performance testing generates quantitative data which can be used to help you select the right filter material/material combination and the optimal EFA required to meet or exceed your specific performance endpoints for flow rate, throughput, and service life.  
Tests to consider:

Particle Retention: Measure how well the filter captures particles. 

• Flow Testing: Assess flow rates and pressure drop. 
• Biocompatibility Characteristics: Assess characteristics of filter as part of finished device risk assessment.  
• Chemical Resistance: Test against relevant substances. 
• Filterability Trials: Use a small amount of your product to generate quantitative data.

Saint-Gobain understands that performance testing and biocompatibility characteristics are unique to each application.  We will work with you to build out the appropriate test plan for your application.  

Rather than settling for what’s available off the shelf, collaborate with Saint-Gobain to adopt a holistic approach to filter design that combines customization, strategic consultation, and the integration of cutting-edge technology. By incorporating the right design features from the start of your project, you can unlock the full potential of your filters. Customized features needn’t add to the overall cost of your filter and can minimize the impact of downtime and equipment servicing in the long run. You can rely on our engineering expertise to guide you through the process. 

Let’s get started!