It’s been six years since the launch of startup company , co-founded by Professor Mark Rentschler of the Paul M. Rady Department of Mechanical Engineering. The company has seen great success, including the development of a medical device designed to enable more efficient procedures in the small bowel region.

Today, with the help of a $4.5 million award through the Anschutz Acceleration Initiative (AAI), Rentschler and his colleagues are working to bring two new products to the market that will transform these types of procedures even further.

“We brought our first product out on the market in 2024,” said Rentschler, also a faculty member in biomedical engineering (BME) and robotics. “We are planning to bring a second and third product to the market in 12-18 months, and we are extremely excited to get these devices in the hands of interventional endoscopists.”

Professor Mark Rentschler holding Aspero Medical's patented Ancora-SB balloon overtube.

In 2023, Aspero received clearance from the Food and Drug Administration (FDA) to market and sell the Ancora-SB device. The product is used during endoscopy procedures to diagnose and treat small bowel diseases.

According to Rentschler, operating within the small intestine can be time consuming and technically challenging. Equipped with a patented micro-textured balloon, the Ancora-SB overtube is designed to provide more traction and anchoring consistency than smooth latex or smooth silicone balloon overtube competitors.

“Balloon overtubes for small bowel procedures have been around for about a decade,” said Rentschler. “We’re not looking to change the small bowel enteroscopy procedure, but instead improve balloon anchoring performance during these procedures in the small bowel.”

Ancora-SB has allowed Aspero to prove their worth in hospitals. Their next products expand on this concept, of course, with additional features that can facilitate a less invasive interventional procedure than traditional open surgery.

The next generation balloon overtube will be used to remove cancerous lesions in the large bowel region. It features an extra working channel that allows for an additional tool to be utilized alongside the visualization scope. This offers physicians more control, access, and stabilization when maneuvering through the colon and performing advanced interventional procedures.

“Conceptually, these devices will enable triangulated surgery with two tools and centralized visualization so that physicians can more efficiently perform surgery from inside the lumen,” Rentschler said. “Instead of historically invasive procedures, where the patient is cut open, and the cancerous bowel region is removed, we’re assisting physicians as they remove the cancer from the inside of the lumen during an outpatient procedure.

“It's much less invasive, with potentially tremendous cost savings, and numerous benefits for the patient.”

Aspero’s third product will be another balloon overtube, this time with a working channel that enables minimally invasive cancer removal in the esophagus and stomach regions of the gastrointestinal tract.

Rentschler showcasing all three of the medical devices in Aspero Medical's multi-product platform, including their two new highly anticipated devices.

Rentschler and his team say the two upcoming devices have the potential to replace a large, and growing, number of today’s conventional surgical procedures in the gastrointestinal region by enhancing safety and efficiency while reducing patient recovery time. Moving procedures from inpatient surgery to outpatient endoscopy can generate potential cost savings of up to 50 percent or more.

“Everyone knows this is the direction we need to go. Clinical outcomes from these types of procedures are incredibly strong, but the techniques and devices aren’t widely available yet,” said Rentschler. “We are creating products that help physicians and patients feel safe and comfortable without overcomplicating things. The paradigm is rapidly shifting, and we endeavor to push endoscopy forward.”

The company is currently finalizing the design of the second product. It’s about six months further along in development than the third product, but Rentschler says they are looking to have both devices FDA cleared by the end of 2026.

When all three devices hit the market, Aspero will look to market a portfolio of products, rather than a single tool. But further innovation is on the horizon, this time incorporating the Ancora balloon technology with a robotic element.

“Ancora is a multi-product platform focusing on the small bowel, large bowel, stomach and esophageal regions,” Rentschler said. “Our next potential venture will be in flexible robots. We’ll continue with our balloon overtubes, but as anchoring platforms to be used with flexible robotic endoscopy systems.”

Until then, Rentschler and company are full steam ahead on these next products. The $4.5 million AAI grant is being offered over a four year span, but they anticipate spending that money much sooner so they can get the devices out on the market and begin positively impacting patients and physicians everywhere.

But that’s not their only goal. With a lot of Colorado involved in the company’s revolutionizing technology, Rentschler hopes to also tell another story.

“I started Aspero Medical with Dr. Steven Edmundowicz at CU Anschutz. We’ve received a number of grants from the state of Colorado and everyone involved is invested in our vision,” said Rentschler. “We believe that a rising tide raises all boats, and when we think of Aspero, we want it to be a successful Colorado story.”

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Next week’s University of Colorado Showcase is bringing together all that is great about entrepreneurship and innovation across our four campuses.

Our community is made of diverse industries and perspectives – in this case, that of a biomedical professor at CU Boulder who is also the CEO of Aspero Medical.

Mark Rentschler is a tenured professor of mechanical engineering with roles in biomedical engineering, robotics at CU Boulder and surgery at CU Anschutz. He leads the Advance Medical Technologies Laboratory, innovating “smart” medical devices and surgical robotics with support from NSF, NIH and industry partners.

His lab focuses on advancing health care technologies toward a futuristic operating room. As the founding CEO of Aspero Medical, a CU spin-out, Rentschler drives innovation in gastroenterology devices. The company’s FDA-cleared device is on the market, with a promising pipeline for future commercialization.

Here’s a Q&A with Rentschler:

You are interestingly both a professor and a CEO. Which came first, professorial life or private sector life? And how did you move into the other?

It was a bit of both, almost in parallel. Before I started at CU, I spent two years as the first employee in a startup that spun out of a university based on my Ph.D. research. Here is where I was likely first bitten by the entrepreneurial bug. Coming to CU then as a professor, I anticipated spinning technology out at some point, but didn’t anticipate leading the company.

As a deep tech founder, much of the early time at the company was heavy in technical development, so it’s been a reasonably smooth transition to picking up the additional skills needed to lead a small spin-out company.

How has being part of CU Boulder affected your innovations and entrepreneurship?

CU has been extremely supportive of my entrepreneurial pursuits. While there are roadmaps, rarely is there a perfect blueprint for how to translate technology out of a university. CU has been flexible and creative in helping me and my co-founder establish a startup and spin the tech out of the university.

With your unique perspective, how do you see the CU campuses helping or encouraging faculty in their innovation and entrepreneurship journeys?

What I see as a major strength is that CU doesn’t see one size fits all. There is creativity and willingness to try different approaches to supporting faculty and entrepreneurs in an effort to move tech along in an efficient manner. The willingness to try and fail, with emphasis on failing early, is something I’ve observed as a hallmark of success.

CU Showcase is Oct. 4

Meet Rentschler and other members of the CU ecosystem at next week’s CU Showcase, which brings together ventures spanning quantum tech, AI, health care, the arts and more, all tackling big challenges for our state and world. This gathering celebrates their hard work and aims to spark serendipitous connections and creative collaborations that will shape the future of Colorado and our university system.

We hope to see you there: You are the showcase!

Event Details

• When: 1-6 p.m. Oct. 4
• Where: CU Anschutz Medical Campus
• Register
• Learn more about the initiative

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, a CU spin-out company co-founded by Professor Mark Rentschler, has received clearance from the Food and Drug Administration (FDA) to market and sell the Ancora-SB small bowel balloon overtube that incorporates the company’s patented Pillar micro-texture balloon technology. The Ancora-SB device is used for small bowel enteroscopy procedures.

“We are incredibly pleased to receive FDA 510(k) clearance for the Ancora-SB device, and look forward to seeing the anticipated clinical benefits,” said Dr. Rentschler, Aspero Medical CEO. “We believe this novel balloon design will have a significant impact for both caregivers and patients.”

Balloon endoscopy has become the standard of care in the drive to diagnose and treat small bowel disease. Unlike the Aspero Medical Pillar balloon, which is characterized by the addition of a proprietary gripping micro-texture, current balloons are smooth and round, making them prone to slippage. Ineffective balloons are estimated to result in significantly increased annual healthcare costs annually due to incomplete or lengthened procedures.

“The ever-increasing number of patients suffering with small bowel disease requires that we look to develop innovative diagnostic and treatment options, including devices like the Ancora-SB which is designed to enable more efficient small bowel enteroscopy procedures,” said , Chief Medical Officer for Aspero Medical. “We look forward to ensuring that the Ancora-SB is available for all cases where the innovative design can make a difference.”

Ancora-SB, a next-generation balloon overtube for GI endoscopy procedures, was initially developed in part through grant funding from the State of Colorado’s Office of Economic Development and International Trade and through National Institutes of Health (NIH) SBIR grant funding. Aspero Medical is continuing to innovate in GI endoscopy, and plans to expand the Ancora platform as additional products are brought to market in the near future.

“There are significant limitations with current technology used in gastrointestinal endoscopy procedures, but Aspero has developed an alternative that will potentially improve performance of certain procedures, save time for practitioners and patients, and improve patient outcomes,” said Mike Freeman, Innosphere Ventures general partner. “We look forward to continuing to support the company and the ongoing product development efforts.”

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Imagine an iPad that’s more than just an iPad—with a surface that can morph and deform, allowing you to draw 3D designs, create haiku that jump out from the screen and even hold your partner’s hand from an ocean away.  

That’s the vision of a team of engineers from CU Boulder. In a new study, they’ve created a one-of-a-kind shape-shifting display that fits on a card table. The device is made from a 10-by-10 grid of soft robotic “muscles” that can sense outside pressure and pop up to create patterns. It’s precise enough to generate scrolling text and fast enough to shake a chemistry beaker filled with fluid.

It may also deliver something even rarer: the sense of touch in a digital age.

“As technology has progressed, we started with sending text over long distances, then audio and now video,” said Brian Johnson, one of two lead authors of the new study who earned his doctorate in mechanical engineering at CU Boulder in 2022. “But we’re still missing touch.”

Johnson and his colleagues described their shape display July 31

The group’s innovation builds off a class of soft robots pioneered by a team led by Christoph Keplinger, formerly an assistant professor of mechanical engineering at CU Boulder. They’re called Hydraulically Amplified Self-Healing ELectrostatic (HASEL) actuators. The prototype display isn’t ready for the market yet. But the researchers envision that, one day, similar technologies could lead to sensory gloves for virtual gaming or a smart conveyer belt that can undulate to sort apples from bananas.

“You could imagine arranging these sensing and actuating cells into any number of different shapes and combinations,” said Mantas Naris, co-lead author of the paper and a doctoral student in the Paul M. Rady Department of Mechanical Engineering. “There’s really no limit to what these technologies could, ultimately, lead to.”

Playing the accordion

The project has its origins in the search for a different kind of technology: synthetic organs.

In 2017, researchers led by Mark Rentschler, professor of mechanical engineering and biomedical engineering, secured funding from the National Science Foundation to develop what they call sTISSUE—squishy organs that behave and feel like real human body parts but are made entirely out of silicone-like materials. Co-investigators on the grant include Keplinger, now a director at the in Germany; Nikolaus Correll, associate professor in the Department of Computer Science at CU Boulder; and Sean Humbert, professor of mechanical engineering.

“You could use these artificial organs to help develop medical devices or surgical robotic tools for much less cost than using real animal tissue,” said Rentschler, a co-author of the new study.

In developing that technology, however, the team landed on the idea of a tabletop display. The research is part of the Materials Science & Engineering Program.

The group’s design is about the size of a Scrabble game board and, like one of those boards, is composed of small squares arranged in a grid. In this case, each one of the 100 squares is an individual HASEL actuator. The actuators are made of plastic pouches shaped like tiny accordions. If you pass an electric current through them, fluid shifts around inside the pouches, causing the accordion to expand and jump up. 

The actuators also include soft, magnetic sensors that can detect when you poke them. That allows for some fun activities, said Johnson, now a postdoctoral researcher at the Max Planck Institute for Intelligent Systems.

“Because the sensors are magnet-based, we can use a magnetic wand to draw on the surface of the display,” he said.

Hear that?

Other research teams have developed similar smart tablets, but the CU Boulder display is softer, takes up a lot less room and is much faster. Each of its robotic muscles can activate as much as 50 times per second. 

The researchers are focusing now on shrinking the actuators to increase the resolution of the display—almost like adding more pixels to a computer screen.

“Imagine if you could load an article onto your phone, and it renders as Braille on your screen,” Naris said.

The group is also working to flip the display inside out. That way, engineers could design a glove that pokes your fingertips, allowing you to “feel” objects in virtual reality. 

And, Rentschler said, the display can bring something else: a little peace and quiet. 

“Our system is, essentially, silent. The actuators make almost no noise.” 

Other CU Boulder co-authors of the new study include mechanical engineering graduate students Vani Sundaram, Angella Volchko and Khoi Ly; and alumni Shane Mitchell, Eric Acome and Nick Kellaris.

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