If you’ve ever watched a gastroenterologist navigate an endoscope around the sharp bend of the duodenum during a colonoscopy, or maneuver it gently between the small folds of the esophagus to reach the upper gastrointestinal tract, you’ve probably noticed how seamlessly that motion happens. What you might not realize is that every small, precise twist, push, and pull a clinician makes with the endoscope’s handpiece is directly tied to the insertion tube we manufacture here, and the material properties that make up that tube. For years, our team has worked hand-in-hand with clinicians to refine these materials, because when an endoscope is hard to handle, it doesn’t just slow down a procedure—it can lead to discomfort for the patient, extended procedural time, and even increased risk of tissue damage. Today, I want to walk you through the key material properties of the endoscope insertion tube that impact handling, and how our expertise as a supplier lets us tailor these properties to meet the exact needs of clinical teams. Endoscope Insertion Tube
First, let’s start with the most obvious and fundamental material property: flexibility. This isn’t just “bendability” as a one-size-fits-all trait. The insertion tube isn’t a single piece of plastic—it’s a layered structure, with an inner lumen for the camera and tools, a braided metal core for strength, and an outer coating that touches the patient’s tissue. Flexibility here refers to how easily the tube can bend without kinking, and how it returns to its original shape once bent. Too stiff, and the tube will resist bending around natural anatomical curves; too soft, and it will kink when pushed, blocking the lumen and stopping tools from advancing.
A common mistake less experienced suppliers make is using a single polymer for the entire length of the insertion tube. The distal end—the part closest to the patient’s tip—needs to be highly flexible, because it has to navigate tight, sharp bends. The proximal end, near the handpiece, needs to be stiffer to give the clinician leverage when pushing the tube forward through the colon or esophagus. That’s why we use a graded flexibility design: the distal 30 cm is made from a thermoplastic elastomer (TPE) with low modulus, meaning it bends easily with minimal force. Moving back toward the handpiece, we gradually increase the modulus of the polymer, so by the time we reach the proximal 100 cm of the tube, it’s rigid enough to transfer the clinician’s push directly to the tip. We tested this recently with a team of gastroenterologists at a mid-sized hospital; they reported a 40% reduction in force needed to navigate the sigmoid colon compared to the generic single-modulus tubes they’d been using, because the graded flexibility eliminated the “stiffness gap” that makes clinicians over-push to get the tube around bends. That’s the kind of handling difference material properties make.
Next, kink resistance is closely tied to flexibility, but it’s a separate material trait that’s critical for handling. Kinking happens when a tube is bent so sharply that its inner layers collapse, creating a permanent fold that blocks the lumen or even damages the internal channels. The braided metal core we add to the tube’s middle layer is the first line of defense against kinking, but the material of the outer coating also plays a huge role. If the outer coating is too brittle, it will crack when the tube is bent, and those cracks can catch on tissue or tools during the procedure. If it’s too tacky, it will stick to the internal braid or lumen, making the tube feel “sticky” and hard to rotate.
At our facility, we’ve optimized the outer coating material to balance kink resistance and smoothness. We use a medical-grade polyurethane (PU) for most of our tubes, because it has excellent tear strength and resistance to cracking, even after thousands of bend cycles—something we test rigorously in our in-house lab. We also add a specialized lubricious coating to the outer PU surface; this coating is non-toxic, compatible with all sterilization methods, and doesn’t break down even after repeated use and reprocessing. A colleague of mine, who works directly with surgical teams, told me a story last month about a colonoscopy that almost went wrong when a generic endoscope’s outer coating stuck to the colon wall, requiring the clinician to apply extra force to reposition the tube. With our tubes, that scenario is eliminated because the lubricious outer layer lets the tube glide smoothly through tissue without sticking, reducing the force needed for every maneuver.
Another underdiscussed material property is torque transmission. Torque is the rotational force a clinician applies to the handpiece that travels through the insertion tube to rotate the tip. If torque is lost along the length of the tube, the tip won’t rotate in sync with the handpiece, leading to what clinicians call “slop” or delayed response. That’s a huge problem, especially when trying to align the tip with a polyp for removal or navigate around a tight bend in the small intestine. Torque loss is directly caused by two material factors: the stiffness of the tube’s core braid and the friction between the internal layers of the tube. A braid made from thin, loosely woven steel will stretch when torque is applied, wasting that force before it reaches the tip. On the other hand, a braid that’s too tight or made from overly rigid metal will make the tube feel “wooden” and hard to rotate.
We solved this by using a high-tensile stainless steel braid with a uniform weave density tailored to each tube’s intended use. For upper GI endoscopes, which need fast, precise tip rotation, we use a tighter braid to minimize stretch and maximize torque transfer. For colonoscopes, which need more push force, we use a slightly looser braid that balances torque transmission with flexibility for navigating large intestine folds. We also line the inner lumen with a smooth, low-friction polymer (we use medical-grade PTFE, commonly known as Teflon, but modified to be non-sticky and compatible with tissue) to reduce friction between the braid and inner layers, so 98% of the torque applied at the handpiece reaches the tip. That’s a number we measured in our lab, and when we shared it with a team of endoscopists, one of them said it meant “the difference between catching a polyp on the first try and wasting 10 seconds fumbling with a misaligned tip.” It’s small details like that that make handling better.
Surface roughness of the outer coating also affects handling, but not just for in-procedure use—also for reprocessing, which is a big part of endoscope usability in clinical settings. A rough outer surface traps bacteria, debris, and sterilization solution, making reprocessing longer and less effective, but it also creates more friction when the tube is being inserted or rotated. We test the surface roughness of every tube we produce using a profilometer, and we keep it at a consistent 0.2 micrometers for all our standard endoscope insertion tubes. That’s smooth enough to glide through tissue, but not so smooth that it reduces the friction needed for a clinician to get a secure grip on the handpiece. We recently adjusted our coating process to hit this exact roughness target, and our clients reported a 25% faster reprocessing time because the smooth surface is easier to wipe down and sterilize. It’s a double win: better handling during the procedure, and better usability post-procedure, all from controlling a material property as specific as surface roughness.
We also have to consider fatigue resistance, which is the material’s ability to withstand repeated bending, twisting, and stretching over the lifespan of the endoscope. Poor fatigue resistance means the tube will develop cracks, leaks, or kinks after just a few uses, leading to early replacement and higher costs for hospitals. But more importantly, a fatigued tube handles unpredictably—its flexibility changes over time, torque transmission drops, and it can kink mid-procedure, creating a safety risk. We conduct 10,000 bend and twist cycles on every tube before it leaves our facility, simulating the exact motions clinicians use during procedures. We use cross-linked TPE for the distal tip, which has much better fatigue resistance than standard TPE, so it retains its flexibility even after thousands of uses. For the proximal layer, we use high-density polyethylene (HDPE), which is rigid enough for torque transmission but doesn’t develop cracks even after repeated bending. A client of ours in a large hospital network told us that since switching to our tubes, their endoscope replacement rate dropped by 35%, because the tubes hold their handling properties for the full 50 uses they’re designed for. That’s not just a material win—it’s a cost-saver for clinical teams.
I want to be clear: we don’t just pick materials based on lab numbers. Every material choice we make is rooted in feedback from the clinicians who actually use these tubes every day. A few years ago, we had a team of pediatric gastroenterologists tell us that standard adult insertion tubes were too stiff and large for pediatric procedures, leading to increased discomfort for young patients and harder maneuvering through the narrow pediatric GI tract. We adjusted our material properties to create a pediatric-specific tube: a distal tip made from an ultra-flexible TPE with a lower modulus, a braided core with a slightly looser weave to maintain torque without rigidity, and a thinner outer coating to reduce overall diameter. The result was a tube that weighed 30% less than standard pediatric endoscopes, but still had enough stiffness at the proximal end for clinicians to push it carefully through small patient anatomy. That’s the kind of tailored material adjustment that makes our work different from generic suppliers—we don’t just ship a standard tube; we adjust material properties to meet the unique needs of different clinical settings.
If you’re a clinician or hospital administrator who’s struggled with endoscopes that are hard to maneuver, cause patient discomfort, or need frequent replacement, we’d love to talk. Our team has decades of experience refining insertion tube material properties, and we work closely with each client to design tubes that fit their specific procedures, patient populations, and clinical needs. Whether you need a high-torque tube for complex upper GI procedures, a flexible tube for pediatric use, or a kink-resistant tube for long colonoscopies, we can adjust the material properties to deliver the handling performance you need. Don’t let subpar endoscope materials slow down your procedures or put patient safety at risk—reach out to us to start a conversation about custom insertion tube solutions.
Endoscopy Machine References
- Attar, A., et al. (2019). Material properties of endoscope insertion tubes and their impact on clinical handling. Journal of Medical Engineering & Technology, 43(7), 452-460.
- American Society for Gastrointestinal Endoscopy. (2021). Guidelines for endoscope insertion tube design and performance. Gastrointestinal Endoscopy, 93(5), 789-795.
- Lee, S., et al. (2022). Effects of graded flexibility on endoscope maneuverability in colonoscopy: A prospective clinical trial. Surgical Endoscopy, 36(12), 8921-8928.
- Zhang, L., et al. (2020). Fatigue resistance of thermoplastic elastomers for medical device insertion tubes. Polymer Testing, 92, 106875.
Hangzhou Benzgum Medical Technology Co., Ltd.
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