During the day, he designs particle acceleration equipment used to irradiate malignant cells in cancer patients. At night he designs cutting edge wheelchairs for people with disabilities who’d like more agile mobility than what’s offered by standard medical device manufacturers.
Though this may sound like the life of someone in a comic book, Christian Bagg is actually just a talented designer, machinist and inventor. A serial entrepreneur, Bagg lost the use of his lower limbs during a snowboarding accident about 20 years ago and now funnels his entrepreneurial efforts into Icon Wheelchairs. His latest device is an impossible mix of motorbike, tricycle and wheelchair.
We spoke to Bagg to learn about the new Explore wheelchair and how he used modern CAD tools to create it.
3D Modeling Particle Accelerators
Bagg is a machinist by trade, having completed his journeyman apprenticeship just a couple of years before his accident. Since then, however, he has been putting most of his energy into design work. At the Medical Physics Design Lab at the Tom Baker Cancer Centre, this means working with medical physicists to create new tools for their radiation therapy work.
“I work with medical physicists who have no idea how to design something or how to build something,” Bagg said. “They just have a problem, and my job is to solve that problem. It’s kind of awesome because they have no idea how anything is made, nor do they care. They just have the problem. If you solve it with aluminum or carbon fiber or spaghetti, they don’t care, as long as it’s solved.”
Bagg says that the lab has 10 linear accelerator machines, which can run in the $4 million range. When we first tried to reach him on the phone, Bagg had to reschedule our conversation because a piece of equipment at the lab was down. When that happens, Bagg says it’s an all-hands-on-deck situation because the longer a machine is out of commission, the less time there is to apply potentially life-saving treatment to a patient.
Some of the work Bagg performs with the lab involves producing custom fixtures for patients undergoing radiation therapy that can hold a patient’s cancerous limb in place so that it can receivetreatment. Because the linear accelerator, which Bagg describes as a “giant ray gun,” blasts the same cancerous spot repeatedly over 10 to 30 appointments, precision is key.
“Irradiating the same spot is important because ‘therapy’ is sort of a misnomer,” Bagg said.“It’s not necessarily radiation treatment in that it treats cancer. These are basically tissue destroying machines, and they’ll destroy anything that you put in their path. And luckily, your healthy tissue regenerates faster than your cancerous tissue. If they focus in on your cancerous tissue, then that’s how you get rid of the cancer. If you move an inch to the left, then you would destroy healthy tissue. So, placement and aim is paramount.”
Currently, Bagg is designing a cranial spinal irradiation board, which sits on top of the bed with wedges and facemasks so that a patient can be reliably set up comfortably to undergo radiation therapy for 30 minutes or more.
For all of the design work on the irradiation board, which consists of 20 to 30 parts, Bagg uses SOLIDWORKS. He says the software is ideal for the complex assemblies required for building radiotherapy devices. He designs a lot of the parts for these types of devices to be 3D printed, so that he can print them on his Mark Two 3D printer. The printer is capable of reinforcing printed parts with strands of continuous carbon fiber, but it can also print non reinforced parts using a nylon material called Onyx that contains chopped carbon fiber.
“Onyx can be used to 3D print parts with very low density,” Bagg explained. “This works very well for cancer treatment because it doesn’t affect the beam very much, so that the electrons flying through don’t get scattered and dispersed. They just fly straight through the printed part to the area where they’re aimed.”
From Irradiation Devices to Wheelchairs.
The work Bagg performs during the day relates well to what he does when he gets home. Through his company, Icon Wheelchairs, Bagg works with his co founder, 13-time Paralympic medal winner Jeff Adams, to create performance wheelchairs. His most recent design is the Explore, a three-wheeled, electric powered mountain bike.
The Explore features a 3000W electric motor, 52V battery, a stainless steel frame, an articulating front end, a carbon fiber seat pan and a kiteboarding harness system. Altogether, this makes it possible for riders to power up and down 15 miles of biking trails.
Bagg says he came up with the idea for the Explore when he was skiing with his wife and friends. For someone in a wheelchair, the typical device, a sit ski, involves a chair affixed to a set of skis. As he approached the areas of loose snow around tree trunks, known as “tree wells”, he’d have to tilt his bike to avoid wiping out. Unfortunately, for a wheel chair, anything more than a five-degree tilt can mean a tumble into the snow, or, even worse, into a tree.
So that he could continue enjoying the outdoors as he always had, Bagg concocted a bike design that makes it possible to adeptly steer. The device features a parallelogram design that swings the weight of the rider, while also allowing the rider to steer.
To design wheelchairs, Bagg relies on both 3D printing and SOLIDWORKS. The CAD tool allows him to break complex designs into subassemblies that make it easier to examine and modify every component within a given system.
“When you have a lot of parts, it’s easier to keep track of things,” Bagg explained. “With our bike, specifically, there is a lot of articulation and suspension in the front alone, where it leans with an articulating framework. There are 18 bushings in the front. Then, you add in a suspension system that’s independent of the suspension and steering that’s independent of the leaning and suspension. You’ve got a lot of things moving independently that can’t interact with the other system. Mocking that up would be an endless endeavor, if you aren’t able to make those micro adjustments or run analysis the way you can with SOLIDWORKS.”
The software also makes it possible for Icon Wheelchairs to create documentation and renderings for clients and potential clients. Because these aren’t your standard wheelchairs, nor are they your standard bicycles, the models and animations created with the CAD software give potential customers a better understanding of how the machine will work, as well as confidence in how it will perform.
The Mark Two allows Bagg to 3D print complex or oddly shaped parts. For instance, fixtures for the Explore’s tubing are all printed with Onyx. After a year of putting the bike through rigorous testing, Bagg says the printed parts are still going strong. The Mark Two has proven so useful to his work that he plans on getting one or two more of the printers.
While he was designing the Explore, he took his prototype to Easter Seals Camp Horizon, a camp for disabled youth. At the camp, a non verbal girl named Lindsay was able to try out Bagg’s prototype and have an experience she’d never had before.
“As nervous as I was to let her go with it, she went and, when she came back, she had this ear-to-ear grin,” Bagg said. “She told her mom that that was the best day of her life. The impact that that had on me at that moment was pretty profound in the sense that I did really shift from making something just for me into making sure whatever I came up with was going to be good for kids like her.”
After that, Bagg decided to focus on something that could be used by kids like Lindsay, knowing that he’d rather make something that a variety of people could use, not just him. This led to a less aggressive, motor-free version of the Explore dubbed the Trailblazer. The Trailblazer can feature a handle that can be pushed by a guide, while the rider steers where the bike goes.
“It’s easy to make something that works perfectly for me, and it’s harder to make something that works for everyone,” Bagg said. “Once I realized the freedom the bike gave me, the next step was making sure it could give everyone that freedom. I wasn’t going to be the only benefactor of this technology.”