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Industrial Design for Microfluidics: The Good, The Bad, and the Ugly.

Sam White
Sam White January 08, 2021 • 0 min read

In the world of highly-calibrated, fluid-based diagnostics, human-centric design can be the difference between a product that succeeds and one that fails.  

At every scale and in every kind of product, there are opportunities for designers to improve outcomes by thinking deeply about the human. This is true whether you’re designing large, complex machinery or microscopic devices. When you dive deep into a user’s particular world to understand their unvoiced needs, you learn a lot about the promises a product makes to the user, and how to fulfill that promise. Sometimes, if you’re lucky, it allows you to radically rethink what a product should be, or what it can be. 

At Cortex, we think of this as “giving people superpowers.” Thoughtful design combined with killer technology can give people capabilities that they didn’t have before. It can let firefighters see through smoke. Or let people diagnose chronic medical conditions at home, without a clinician. Chasing these opportunities is what gets us out of bed in the morning. 

Today we want to zoom in on a particular area of focus for us in this pursuit, at the intersection of medical diagnostics and industrial design. It’s an area that doesn’t always get enough attention from the product design community, and an area where the medical device community doesn’t always have the industrial design chops to create great experiences:

Microfluidic devices. 

Microfluidic devices use very small amounts of fluid on a microchip to do various laboratory tests. Often they use body fluids, or other solutions with cells or cell parts to diagnose a variety of diseases and conditions. 

For disease diagnostics, microfluidic device design must be exceedingly precise. The device needs to collect a very specific amount of fluid for assessment, whether blood, urine, or — in the case of many of the most common COVID-19 tests on the market — nasal or oral secretions. It’s also highly specific in terms of the timing of the assessment, as well as the user’s hand-eye coordination, because samples must be in the right condition for analysis. 

The level of precision required for collecting these samples can put a whole lot of onus on the end user. On a clinical level, it’s easy to say “we need X microlitres of this fluid, moved under Y conditions, to Z laboratory.” It’s a whole other ballgame to ask an untrained person to provide the exact right sample, in the exact right condition, every time.

That’s why it is most often left up to clinicians rather than end-users to perform. 

Take a look through Health Canada’s list of approved COVID-19 tests, and you’ll see that the vast majority are lab-based or point-of-care — meaning they’re administered by a healthcare practitioner. Health Canada does not expect an untrained person to reliably collect the exact right amount of fluid from their own or their child’s nasopharyngeal passage (I know because I’ve tried). 

This sample collection is the first step in a whole microfluidic process. This is a workflow from the point of collection, to transportation, to the laboratory environment where the sample is aliquoted (separated into its constituent parts, for example to extract blood plasma for certain tests), dissolved, mixed and binded as necessary, and the assay is analyzed. 

It’s also the step where good product design can deliver a tremendous promise: 

What if you made it possible for a patient to self-administer a COVID-19 test? What if you used human-centric design principles to eliminate the possibility that user error renders a test unusable? What if you made it as easy as possible, and as painless as possible? It won’t be via a nasopharyngeal swab. What if you then made it cheap, and widely available? 

The possibilities are obvious for what this could mean for the course of the pandemic. Or future pandemics, for that matter. Getting there in practice is hard.

The first COVID-19 point-of-care tests arrived within weeks after the disease’s emergence. But it took until November for the FDA to approve the first at-home COVID-19 test for individuals 14 or older. That’s because of the difficulty of designing a microfluidic device with a reliable outcome based on these very precise requirements. 

On the one end, you have the human-centric promise to the user: a test that anyone can use. On the other, you have the science that delivers on that promise. 

The work of industrial design begins in bridging that gap. 

Human-centric design has been applied to microfluidic diagnostic devices to great effect in the past. Think about a home pregnancy test. It returns a result within minutes. Crucially, it’s designed to register the presence of the hCG hormone no matter how much fluid is applied to it. This allows for variability in human behaviour. In diagnostics for diabetes, home blood glucose meters have become highly engineered to meet the ISO 15197 standard of being within +/-15% of laboratory conditions. Lancing devices are designed to collect the precise amount of blood to meet these requirements.

VITALITI tricorder designed by Cortex
The VITALITI Tricorder — which might be Cortex’s biggest microfluidic design project.

When Cortex partnered with Cloud DX on the VITALITI Health Monitoring System for the XPrize Competition, the promise to the user was a big one: a “doctor in a box” that can diagnose 19 chronic medical conditions, monitor all 5 vital signs, and stream that data to a cloud server,  without a clinician. 

Delivering on this promise involved a lot of precise microfluidic design. The device features a variety of blood tests for different conditions including a user’s white blood cell count, blood glucose level, LDL cholesterol, hemoglobin level, and hepatitis A detection. The VITALITI app uses a diagnostic flow to detect whether users should take a blood test, and then directs them to the right colour-coded package. Each packet has a lancet and a capillary tube that varies in length based on the amount of blood that needs to be collected for that particular test. The cartridge uses a proprietary method to collect the sample and add buffer solution before ejecting onto a paper-based assay under controlled conditions. 

This approach aims at an integrated user experience: the user doesn’t need to measure anything, or know precisely how much blood needs to be collected. They only need to fill the tube. Their experience is largely the same, no matter the type of test. We’re pretty proud of this subtle piece of user interaction. By eliminating this variable in the test result, we meet the precision required by the science, and the promise made to the user. It’s all part of the same superpower: diagnosis at home.  

As new diagnostics needs emerge, and as science evolves to promise new diagnostic tools and methods, industrial design also has to evolve to deliver those promises to the patient. 

No matter how precise the microfluidic requirements are. 

For other Cortex Design microfluidics projects, check out:

  • Our ongoing project with Raytheon and Purdue University on a COVID-19 point-of-care test kit. 
  • Our work with Voltera — one of Canadian Business’s 500 Fastest Growing Companies — on the V-One desktop circuit board printer.

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