PLASTIC MANIFOLDS 101

In this podcast, Tom Rohlfs, Principal Engineer & President at Controlled Fluidics, provides an overview of bonded plastic manifolds, covering their primary functions and in which industries he sees getting the most use out of them. We then proceed to discuss how they're manufactured and which materials bonded manifolds use most often.

John Maher: Hi, I'm John Maher. I'm here today with Tom Rohlfs, President and Principal Engineer at Controlled Fluidics, a plastics machining company specializing in precision manifolds. And our topic today is plastic manifolds. Welcome, Tom.

Tom Rohlfs: Hey John. Thanks for having me.

John: Sure. So Tom, at its most basic level, what is a manifold?

Tom: So a manifold — we make them in plastic materials — is just a device that allows us to control, be it pneumatics and gas or liquid, essentially taking a single input or output in being able to split it apart into multiple pads. By being able to control your liquid, you can achieve certain processes.

John: Okay. And what are plastic manifolds used for?

Tom: Yeah, so manifolds often see use in devices like the IVD life sciences gene sequencing where an end user wants to take a certain reagent, combine it with other items and produce a result. A good example of this is if in something like COVID testing where they need to test somebody's particular blood for COVID antibodies, they can use reagents and deliver reagents to the blood in an automated fashion and produce a result.

John: Okay. What types of industries use manifolds?

Tom: Often times it's life sciences. We see a lot of work on the life sciences where they're testing IVD, that's all sorts of testing for blood viruses, things like that, gene sequencing. Interesting applications also are in space. Manifolds allow a device to be small, compact. The manifold routing has all the liquids internal to it, so it's allowed to be very small and compact and that finds use in space type applications as well.

John: All right. And talk a little bit about the different methods that you have available to make and manufacture manifolds.

Tom: Yeah, sure. So manifolds can be made generally from a machining process because the channels are internal. It doesn't really speak much to injection molding. So oftentimes it's a machining process. We start with a block of plastic and we would drill holes and cut channels in it. Alternatively, if the channels are very complex, we are capable of splitting the part in two. So we create two halves of a manifold, fuse it together into one monolith, one block.

John: So you'd be able to sort of, like you said, have two pieces of plastic. Do the channels sort of cut those out, cut those out in a reversed way, I suppose, and on the other block and then fuse those two blocks of plastic together so that the channels are inside the plastic in the final product?

Tom: That's right. Make say two mirror images of a channel pattern and then fuse the two pieces together to create one monolith, one working manifold. The advantages to that are a drilled manifold. You have limited drills that only go straight. So you have limited options on what you can do for your internal channel pattern. By using a bonded manifold, you're able to do far more complex channel routings for more complex processes.

John: Do the final manifolds have any kind of way to direct the fluid through those various channels? Do they have little on and off switches or anything like that? Or valves, if you will, that direct where the fluid goes?

Tom: That's a great question. So absolutely, almost every manifold comes with valves, right? The valve is the switch, as you described it, to control the flow of the liquid or the gas. So a valve might let a liquid or a gas into the manifold, then valves help direct it to various ports depending on the application.

Along with valves, you can have integrated sensors, of course, like pressure sensors or temperature sensors as well as pumps. You need something to actually move the working fluid. Oftentimes a customer will incorporate a pump to actually help move that liquid through the manifold. So manifolds can have pretty much any sort of external component attached to it, depending on the need for the application.

John: So all of those valves and pumps and things like that are all sort of external to the plastic manifold itself. They're not embedded into the plastic, if you will.

Tom: In general, yes, the majority of the applications have them on the external, but there are some occasional applications where we'll embed silicone diaphragms, little flow sensors and things like that. So it is possible to embed different devices into the manifold itself, though the most common is external cause as you can imagine, if you had a fail point for a manifold or if you had a failure and it's embedded in the manifold, the manifold now is obviously scrap. Whereas if you have a bad valve and it's external, a simple change out of that valve and you're up and running again.

John: Okay. What are some of the different plastic types that you use in manifolds, and why do you have all these different plastics that you use?

Tom: Sure. So generally speaking, we work with materials that are either machinable. So on the drill manifold side of things, which again is more of a limited layout type of scenario, we can use any stock plastic, any stock material that's available out there. So if you need something that's highly chemical resistant, a customer might pick something like Peak or Teflon. Or if they're looking for something very low cost, they might pick PVC on the drilled manifold side.

For the bonded manifold side, again, more complex applications. These are things that you might see in gene sequence, and we can work with the materials that can be bonded, which is the amorphous plastics. Amorphous plastics, the most common in infused manifolds, would be ultem, polycarbon, and acrylic. Each one of them has their pros and cons for costs, clarity, resistance to chemicals… So it's very much application with that.

John: All right. Well that's really great information, Tom. Thanks again for speaking with me today.

Tom: Sure, glad to help

John: And for more information, you can visit the website at controlledfluidics.com or call 6 0 3 6 7 3 4 3 2 3.