Straining for Relief

As I put fingers to keyboard to write this blog, I’ve recently thrown away my second lightning charging cable since purchasing a new smart device late last year. To say that writing a blog about strain relief was kismet before pitching the cable in the waste can, has to be the understatement of 2017. All of which is a near-perfect segue into the importance of strain relief solutions for plastic tubing assemblies.

If it helps, think of strain relief as a boot or jacket one slips over a delicate plastic tube, increasing its life and mitigating leaks.

In the world of in vitro diagnostics, strain relief solutions relieve tubing of stresses and tensions that may cause the tubing to bend, kink or twist — thereby limiting its inner diameter and impeding fluid flow — which could lead to leaking.

Factors to consider when incorporating strain relief solutions into a design include the size and material of the tubing, the mobility requirement for the tubing, the interaction of the strain relief material with the tubing, and the space available inside the instrument. Standard strain relief options might include springs, spiral wrap, heat shrink or formed plastic sleeves. Another option is to thermoform the entire assembly to avoid unwanted compression.

In addition to limiting leaks, the benefits of strain relief solutions include:

  • Enhancing flex-life performance by limiting over-flexing
  • Preventing kinking
  • Mitigating abrasion
  • Promoting positive fluid flow

For design engineers working on next generation diagnostic instruments, incorporating strain relief solutions early into a design may help one to achieve the accuracy, performance and cost parameters of a project.

Diba delivers exceptional fluidic outcomes across an entire system fluid path. Our proven expertise designing and manufacturing precision fluidic handling systems ensures optimized performance, reliability, and superb field serviceability of instruments in laboratories around the world.

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Tubing Material Selection Can Affect Carryover … Big Time

Labs in the United States run seven to ten billion blood tests annually influencing more than 60% of clinical decision making. On any given day, that’s millions of blood samples running through millions of meters of tubing within today’s most technologically advanced diagnostic instruments. With that many chemistry panels being analyzed, there’s bound to be inaccuracies. The key here is to reduce inaccuracies to as close to zero as possible before a test panel is even run, by optimizing flow path management and through superior fluidic solutions. Carryover from one sample to the next is always a risk.

So, what is Carryover?

Carryover is defined as the remnant of a sample left over in the flow path that gets picked up in a subsequent sample. Although there are several system components which can affect carryover – the aspirate/dispense probe and unswept fluid volume readily come to mind – for now we will focus on tubing material selection.

When a fluid traversing the fluid path picks up some volume of a preceding fluid, it becomes diluted; it no longer has the same concentration. This can be problematic when multiple critical fluids travel through one fluid path.  Changes in concentration can lead to false readings and misdiagnosis.

Materials with low surface energy such as PTFE, FEP, PEEK, ETFE, and MFA are used for the flow path in an effort to reduce fluid carryover. If a fluid flowing through a piece of tubing has a higher surface energy than the tubing itself, it will usually stay bound to itself, and not bind to the inner-diameter surface of the tubing.  This reduces the likelihood of carryover, as the next fluid moving down the flow path may not encounter any of the previous fluid to pick up.

Newly marketed diagnostic instruments and their assays are becoming more and more sensitive. This greater sensitivity is likely to require more stringent control of carryover from one sample being tested to the next. Thus, the tubing choices made for today’s more sophisticated diagnostic analyzers are even more critical than in the past.

Forewarned is forearmed. So, understanding what’s involved with carryover at the onset of a design goes a long way to offering a design solution to help OEMs to solve this problem in today’s more sensitive, precise and faster diagnostic instruments.

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Building Better Engineers Through Kung Fu

When I think of all the people I’ve worked with over the past 30+ years in the engineering world,  few have had more of a profound impact on me than one particular supervisor I worked for several years ago.

When something went wrong, for which he thought I was responsible, he would call me into his office. Rarely, if ever, raising his voice above conversational level, but with surgical precision bordering on the uncanny, he would choose just the right words to verbally slice me into tiny ribbons.  Sometimes, I even thought he was going to fire me!  I would leave his office, head down, dejected and angry about being treated unfairly. He was not the easiest guy to deal with.

One day he called me into his office. As I walked inside, I couldn’t help but think to myself, “Oh great! What did I do now?” But, after I sat down, he began to tell me instead about his Kung Fu training, which began for him as a young man. He even explained to me about the origins of this martial art as well as its philosophies and techniques.  After our “meeting,” I couldn’t help but think, “Wow, that was weird, but really cool!”  I also found it very interesting.  About once a week after that, my boss would call me into his office and he would tell me more about Kung Fu, then send me back to work.

Meanwhile, whenever something “bad” happened, he would continue to call me into his office for those verbal “dismantlings,” that were still extremely unpleasant. And, I would feel angry inside as I did before.  But, once he said what he had to say, his demeanor would change, and he would give me some business advice, and begin again talking about Kung Fu, explaining more about its history, its philosophy and even more about the discipline itself.  By the time I walked out of there, my inner anger had been replaced by a sense of harmony. It was as though he and I were on the same page.  I also felt an inexplicable sense of confidence.

 

Everybody Was Kung Fu Fighting

One particular session that stands out to me to this day, occurred when my supervisor told me about how Kung Fu masters would often be very tough on their students. But, this mode of training was important as it taught the student how to stay calm, to make the right decisions, and to do things the right way.

“If you were my Kung Fu student, and I taught you how to correctly block a punch, and you didn’t do exactly as I’d taught, you would get hit,” he said. “Well, it’s the same way in your professional life!  If I teach you how to handle a situation and you don’t do it the way I’ve taught you, then you will fail.”

At that moment, the light bulb came on! I said to him, “So, you’re using the principles of Kung Fu to mold me into a better engineer?”  “Kevin, he said, I believe that you have potential and I’m trying to bring that out.  When I call you into my office and give you a hard time about something, I am purposely tearing you down.  But, then I’m rebuilding you into the person I know you can be!”

Through my time with that company, this boss continued to alternate between being tough on me, talking about business, and Kung Fu. At times, I still felt like he was being unreasonable and unfair.  But, instead of being angry, I was now smiling, because I understood that, although a bit unconventional, this was his way to help me grow.  And that experience has had a transformational effect on my career.

Wax on.  Wax off.

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My Best Engineering Advice Ever

Life gives us teachable moments on a regular basis. The same may be said about advice, whether given or received.

One piece of sage wisdom given to me way back when, helped me as an engineer and continues to do so even now in my role as Diba’s U.S. National Sales Manager: look to specialists such as Diba Industries, when your project design hits a sticking point or even when you need an additional perspective on a project.

By way of example, discussions I’ve had with engineers designing inline heaters into IVD instruments have revolved around heater performance. Although there are many things to be considered when designing an inline fluid heater, give special consideration to fluid volume, flow rate, size, power, watt density, sensor location and materials. These are just some of the things that can affect the performance of a heater for an IVD application, and are ones that Diba application engineers consider when delivering a custom solution for our customers.

So, take my “best engineering advice ever,” and call on Diba Industries to help you design the ideal fluid handling system to meet the accuracy, performance and cost parameters of your IVD instrument. You might be happy that you did.

What was your best engineering advice you’ve ever given or received? Please share that advice with other readers.

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The Early Bird Gets The Worm Project

The Importance of Early Involvement in a Project’s Design

When designing an In-Vitro Diagnostics (IVD) system, the level of regulations to which the machines are subject are high (i.e., FDA and/or EU approvals). For this reason, these systems go through extended periods of testing in which the form, fit and function of all components are critical to its overall operation. Having a technology partner that is engaged early in the project’s design is key to its long term success.

Once the machines are tested and released into production, the probability for any changes taking place, such as tubing sizes, type of connectors or material/resin changes is highly unlikely.

Resources + Time = Money … Lots of Money!

Let’s say that your new instrument has the requisite approvals from the regulators and is released into production. In order to perform any changes (as small as they may be), the machine – or at least the module in which the change is taking place – has to be revalidated and tested. The revalidation process is usually quite expensive, and it requires resources to document and test the change as well as time to perform the tests. Depending on their complexity, revalidation may take six months or longer to complete.

As a general rule, an OEM will make a change to a system only if:

  • a recurring quality issue exists,
  • a component becomes obsolete, or
  • cost reduction greater than the cost of validation is possible by making the change.

For these reasons, being in the forefront of the system’s design and development is critical. This will enable the component manufacturer to present the OEM with less expensive, easier to manufacture and better performing solutions.  The OEM’s technical team often has a general view of components, but relies on the supplier’s expertise to provide them with the optimal solution.  This can only be done efficiently if the suppliers have full access and are involved in the design of the system early on.

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