Capsule Robot
Curator: Larry H. Berntein, MD, FCAP
Motivation
Medical capsule robots are cm-size mechatronic devices designed to perform medical tasks by entering the human body from natural orifices. Wireless capsule embedding a miniature camera are available since 2000 for diagnosis of small intestine diseases. Due to the complexity of operating inside the human body, capsule robots to date have been designed in an ad hoc fashion, relying on profound expertise acquired through many years of experience
Our Research
We are trying to systematize miniaturized wireless medical device design by creating a cyber-physical design environment that will lower the barriers to design space exploration, thus accelerating progress to prototyping.
A systematic approach to design of pill-size medical devices is possible by outlining the crosscutting constraint that these systems must address. The main ones are (1) size – ideally, a capsule device should be small enough to swallow or to enter natural orifices without requiring a dedicated incision; (2) power consumption — given the limited space available onboard, energy is limited; (3) communication bandwidth – wireless signals must be transmitted through the human body with a sufficient data rate; (4) fail safe operation — since the device is deep inside the human body, the user has no access to it; and (5) effective interaction with the target site, according to the specific functions the device is required to fulfill. Given these common constraints, it is possible to identify a general system architecture for a pill-size medical consisting of the following general modules: (1) a central processing unit (CPU), that can be programmed by the user to accomplish a specific task; (2) a communication submodule, that links the device with user intent; (3) a source of energy that powers the system; and (4) sensors and (5) actuators, both of which interact with the surrounding environment to accomplish one or more specific tasks. It is also desirable for the designers to have a model of the environment, in order to predict the effectiveness of the specific design in accomplishing the desired task.
Starting from this systematic approach, we are creating a web-based cyber-physical design framework that will offer different options for the basic submodules of the capsule robot that can be integrated to obtain a simulation of the expected performance. The main goal of the design environment is to lower the barriers to design space exploration, accelerating progress to prototyping, and increasing the probability of success for each prototype.
You May Be Swallowing a Capsule Robot in the Near Future
Through a website and a paper revealed at a pair of Institute of Electrical and Electronics Engineers (IEEE) conferences, Assistant Professor of Mechanical Engineering Pietro Valdastri, Associate Professor of Computer Engineering Akos Ledeczi and their team made the capsule hardware and software open-source.
The paper, titled “Systematic Design of Medical Capsule Robots,” ran in a special issue of IEEE Design & Test magazine dedicated to cyber-physical systems for medical applications. Within years, Vanderbilt’s capsule robots, made small enough to be swallowed, could be used for preventative screenings and to diagnose and treat a number of internal diseases.
“We’ve done custom capsule design – one for the colon, one for the stomach, another one with a surgical clip to stop bleeding – but we saw we were basically reusing the same components,” said Valdastri, director of Vanderbilt’s Science and Technology of Robotics in Medicine (STORM) Lab. “Like it is with Lego bricks, you can reassemble them for different functions. We wanted to provide the people working in this field with their own Lego bricks for their own capsules.”
Now research groups with hypotheses about how to use the capsules won’t have to redesign boards and interfaces from scratch, which means they can get to the prototyping stage faster.
Medical capsule robots differ from the PillCam, put on the market in 2001, because they can be manipulated to perform internal tasks rather than just passing through the body and recording video.
The paper explains the hardware modules available, which handle computation, wireless communication, power, sensing and actuation. Each is designed to interface easily with new modules contributed from other research groups.
On the software side, Vanderbilt engineers used TinyOS — a free, open-source, flexible operating system — to develop reusable components.
Ledeczi, senior research scientist at Vanderbilt’s Institute for Software Integrated Systems, said a medical capsule robot is the ideal example of a cyber-physical system.
It must work inside the challenging physical environment of the human body, sense its environment and move through it effectively, and then complete tasks such as release a drug, take a tissue sample or deploy a clamp. Finally, it must constantly communicate with a base station through the entire process.
“Our focus is the design environment, not the software per se, with the goal of easing the learning curve for new researchers and engineers who start in this field,” Ledeczi said. “Designing a capsule from scratch requires deep hardware, software and domain expertise.”
By providing a hardware and software component library and the tools to make their composition easy, Vanderbilt opens up the field of medical capsule robots to engineers and scientists who have great ideas but aren’t hardware or software experts, plus makes development costs far more affordable, he said.
Already, the Royal Infirmary of Edinburg in Scotland, Chinese University of Hong Kong, Chonnam National University in South Korea and a number of other institutions have demonstrated an interest in using the technology.
The team presented its work at the IEEE/RSJ International Conference on Intelligent Robots and Systems in Hamburg, Germany, in September and the IEEE International Conference on Robotics and Automation in Seattle, Washington, in May.
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