There’s a wet, squishy tube 9 meters (30 feet) long that carries food from your mouth to your stomach and on through the gut. At times it will get folded over and over (to fit into your belly). This digestive tract is where your body slowly breaks down food, absorbing what it needs for energy and health. Anything not needed will exit out its end — and unceremoniously into your toilet — as waste.
As the entry portal for all food and water, its function and health is pivotal to life. But when symptoms suggest a problem, doctors can find it a tough place to explore.
Certain symptoms that might suggest disease, such as cancer, lurk within its enormous span. Maybe doctors will need to deliver a drug at some precise milepost along the path. They might even need to retrieve something small — such as a penny or battery swallowed by a young child.
Today, to see inside this tube of wet digesting food and wastes, doctors often turn to a tiny video camera. It’s shaped like a pill and about that size. After swallowed, it slides down the throat, into the stomach and on through the intestines. Eventually it will exit out the other end. A doctor can pore over the images it captures throughout its voyage.
But that camera only takes video. It can’t treat disease or retrieve a penny. That’s why doctors are now teaming up with engineers to build tiny robots. One day, these mechanical devices might deliver medicine on demand. Or they might cut out a tiny tissue sample, called a biopsy (BYE-op-see), in which doctors can check for signs of cancer.
Such devices offer to make medical procedures safer and more comfortable. They may also deliver new and better views of the inner you.
Crawling through the colon
Swallow a bite of pizza or spoonful of custard and the digestive tract takes over. By squeezing and releasing, the tube slowly pushes anything you ate or drank down and around the gut. Swallow a pill-like camera and the same thing happens. The body pushes it through the digestive tract. But these new robots aren’t just passive tools along for the ride. They may crawl or wiggle through the body. They can move backward or forward at the command of your doctor.
Once they’re done, these gut crawlers then leave the body just like a regular piece of waste.
David Zarrouk is a professor of mechanical engineering at Ben-Gurion University in Beer-Sheva, Israel. He and his team are building such a robot. It carries a motor to power its worm-like wiggling. Small electronic sensors inside it collect data on the robot’s precise position in the body. A smooth artificial skin lets the robot snake through the stomach and intestines without damaging them.
This worm-bot is known as SAW. That’s short for single-actuator wave robot. An actuator (ACK-shoo-ay-tor) is a part of a machine that makes the entire device move in response to some signal.
Zarrouk has always been interested in building small robots that move in unusual ways. He started working on the worm-like robot in 2015. SAW “will be very smooth and small enough to pass through the body,” he says. It should be able to deliver drugs. And, he notes, “In case it breaks down, it can continue on its own. The digestive system would take it out of the body.”
The Ben-Gurion team is using a 3-D printer to build the robot out of plastic. Eventually they plan to make the robot from special materials that will not irritate human tissue. “We try to use soft surfaces that are not going to cause damage,” Zarrouk explains, “because the intestines are very flexible.”
Zarrouk has already started testing SAW in the intestines of pigs. They were donated by a local cooperative farm, or kibbutz (Kih-BOOTZ). Engineers and computer scientists are now working to shrink the robot’s size, yet keep it powerful enough to perform its job. Zarrouk hopes to be ready to test the device in people sometime later this year. However, he adds, it won’t be ready for widespread use until long after that.
Origami for the gut
While the Israeli team is making robots that crawl through the gut, researchers in Boston, Mass., are at work on a tiny robot that will unfold at its worksite like a mini-umbrella. They believe their device offers the best approach to exploring the digestive system without causing problems or getting stuck.
“It is an origami-style robot,” explains Daniela Rus. She’s a professor of electrical engineering and computer science at the Massachusetts Institute of Technology in Cambridge.
“We can actually squish the robot into the shape and size of a pill,” she says.
The device will be frozen in ice before a patient swallows it. Once warmed in the stomach, the ice will melt. This will cause the robot to unfold and start moving.
The engineers in Rus’ lab would drive this robot with a magnet passed along the outside of the body. They’re currently working with a simulated stomach. The magnet pulls the robot in the direction a doctor wants it to go. Right now, the robot is just an early prototype to prove that the idea could work. Eventually, the researchers hope to build a device that a doctor can drive using a small camera, a video screen and a joystick.
Rus says that once a patient swallows this robot, a doctor could use it to remove small samples of tissue. It also might be used to stop sores, called ulcers, from bleeding. It should be able to deliver medicines to specific parts of the body. It might even remove foreign objects — including those coins, paper clips or other things that toddlers sometimes swallow.
“What we are excited about is using these technologies as mini-surgeons,” Rus explains.
The robots in Israel and Boston won’t be ready to use in patients for several years. Why? It takes time for researchers to develop the technology in the lab. Then they must test it in animals. After that, they must conduct even more tests to make sure it would be safe to use in people.
One doctor in Tennessee is building a new kind of device that he believes will be ready much sooner. It’s not really a robot. It’s more like a camera that doctors can pull into the body to view the colon’s interior.
The colon is the part of the digestive system that sits right above the rectum. It’s the last stop for waste before it leaves the body. Doctors recommend that everyone over age 50 get a procedure called a colonoscopy (Koh-lun-OSS-koh-pee). This lets doctors hunt for signs of cancer.
But many people are afraid of the procedure because preparing for it can be quite uncomfortable, notes Keith Obstein. He’s a doctor at Vanderbilt University in Nashville, Tenn. Patients cannot eat for 12 hours before a colonoscopy. Then they have to drink a special liquid that cleans all the wastes out of their colon. Afterward, doctors insert a device into the rectum called a colonoscope (Koh-LAHN-oh-skoap). It’s a long, flexible tube with a camera and light at the end.
Obstein wants to make use of this scope more comfortable so that more people get the procedure. He’s working with engineers and computer-software designers at Vanderbilt and Leeds University in England.
An endoscope is a camera-tipped tool for peering deep inside the body. Their new one is a flexible, magnetic endoscope. It’s fitted with a small robot arm and tools for taking tissue samples.
This scope is attached to a very thin tether. After inserting it into a patient’s rectum, the doctor can gently pull it forward with a magnet, instead of pushing it from behind. The tether makes the new robotic device easier to maneuver inside the delicate colon. It’s also less likely than a thicker tube to twist into a knot.
Because this scope can see and do more than a normal colonoscope, it should provide doctors more information on the health of someone’s colon. That’s important because each year colon cancer kills more than 50,000 people in the United States alone. In most cases, there are few symptoms before the disease has become too advanced to treat easily.
“Colon cancer is a significant killer,” Obstein says. He hopes his flexible magnetic probe will make a difference for patients and the doctors who treat them.
One of his graduate students, Piotr Slawinski, is working on the design of this new device. The most important thing, he says, is minimizing the risk it might pose to future patients.
“We are definitely hoping to be in a human patient within the next two years,” Slawinski said. “We are doing the best we can to be as safe as possible.”
All of these new devices are bringing doctors, engineers and robots together, with the goal of making medicine safer.
A 1966 science-fiction movie called Fantastic Voyage involved doctors shrinking themselves to fit into a microscopic vessel. Then they were injected into the bloodstream of a scientist and given one hour to move up to his brain where they had to treat a deadly blood clot. Clearly, doctors can’t shrink themselves to the size of blood cells. They can’t even go into the far bigger confines of the human gut. But by sending in tiny robotic explorers, doctors might just accomplish fantastic tasks that only a few decades ago were considered truly impossible.
actuator A motor that provides power to make something happen. It can use any source of power, from water to electricity to a hand crank.
biopsy The removal and examination of a small sample of tissue to discover the presence, cause or extent of a disease, including cancer.
cancer Any of more than 100 different diseases, each characterized by the rapid, uncontrolled growth of abnormal cells. The development and growth of cancers, also known as malignancies, can lead to tumors, pain and death.
colon (in biology) The majority of the large intestine, it runs between the cecum (a pouch below the small intestine) and the rectum. Foods are not digested in the colon, although this tissue lubricates wastes that will be excreted. Some liquids and salts, however, will be removed from materials stored in the colon before excretion.
colonoscopy A medical procedure whereby a doctor inserts a flexible fiber-optic instrument into the rectum and up through the colon. A camera on the instrument sends back images so the doctor can scan for signs of cancer.
computer science The scientific study of the principles and use of computers. Scientists who work in this field are known as computer scientists.
digestive tract The tissues and organs through which foods enter and move through the body. In people, these organs include the esophagus, stomach, intestines, rectum and anus. Foods are digested — broken down — and absorbed along the way. Any materials not used will exit as wastes (feces and urine).
endoscopy A medical procedure in which a doctor inserts a long, slender tube into the body. A light on the end of the device, known as an endoscope, illuminates tissues. Typically, there will be a camera next to the light. It will send back video imagery of the body’s interior.
engineer A person who uses science to solve problems. As a verb, to engineer means to design a device, material or process that will solve some problem or unmet need.
engineering The field of research that uses math and science to solve practical problems.
graduate student Someone working toward an advanced degree by taking classes and performing research. This work is done after the student has already graduated from college (usually with a four-year degree).
gut An informal term for the lower part of the digestive tract, especially the intestines.
magnet A material that usually contains iron and whose atoms are arranged so they attract certain metals.
maneuver To put something in a desired or necessary position by using one or more skilled movements or procedures.
mechanical Having to do with the devices that move, including tools, engines and other machines (even, potentially, living machines); or something caused by the physical movement of another thing.
motor A device that converts electricity into mechanical motion. (in biology) A term referring to movement.
origami The traditional Japanese art of paper folding. It starts with a flat sheet of paper. Through folding — and no cutting — the paper can be carefully folded into decorative 3-D structures, such as a bird in flight.
plastic Any of a series of materials that are easily deformable; or synthetic materials that have been made from polymers (long strings of some building-block molecule) that tend to be lightweight, inexpensive and resistant to degradation.
prototype A first or early model of some device, system or product that still needs to be perfected.
risk The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)
robot A machine that can sense its environment, process information and respond with specific actions. Some robots can act without any human input, while others are guided by a human.
sensor A device that picks up information on physical or chemical conditions — such as temperature, barometric pressure, salinity, humidity, pH, light intensity or radiation — and stores or broadcasts that information. Scientists and engineers often rely on sensors to inform them of conditions that may change over time or that exist far from where a researcher can measure them directly. (in biology) The structure that an organism uses to sense attributes of its environment, such as heat, winds, chemicals, moisture, trauma or an attack by predators.
simulate To deceive in some way by imitating the form or function of something. A simulated dietary fat, for instance, may deceive the mouth that it has tasted a real fat because it has the same feel on the tongue — without having any calories. A simulated sense of touch may fool the brain into thinking a finger has touched something even though a hand may no longer exists and has been replaced by a synthetic limb.
software The mathematical instructions that direct a computer’s hardware, including its processor, to perform certain operations.
technology The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.
tether A tie or cord that loosely anchors some object to a semi-fixed position. Or the process of tying some object to a cord that will keep it loosely affixed to that position. (Consider the child’s game tether ball, whereby a cord it attached to a ball on one end and an anchoring pole on the other end.)
tissue Made of cells, it is any of the distinct types of materials that make up animals, plants or fungi. Cells within a tissue work as a unit to perform a particular function in living organisms. Different organs of the human body, for instance, often are made from many different types of tissues.
tool An object that a person or other animal makes or obtains and then uses to carry out some purpose such as reaching food, defending itself or grooming.
tract A particular, well-defined area. It can be a patch of land, such as the area on which a house is located. Or it can be a bit of real estate in the body. For instance, important parts of an animal’s body will include its respiratory tract (lungs and airways), reproductive tract (gonads and hormone systems important to reproduction) and gastro-intestinal tract (the stomach and intestines — or organs responsible for moving food, digesting it, absorbing it and eliminating wastes).
ulcer An inflamed sore on the skin or on a mucous membrane such as inside the mouth or the wall of the stomach.
waste Any materials that are left over from biological or other systems that have no value, so they can be disposed of as trash or recycled for some new use.
Journal: D. Zarrouk et al. Single actuator wave-like robot (SAW): design, modeling and experiments. Bioinspiration and Biomimetics. Vol. 11, August 2016, p. 046004. doi: 10.1088/1748-3190/11/4/046004.
Journal: M. Shuhei et al. Ingestible, controllable, and degradable origami robot for patching stomach wounds. 2016 IEEE International Conference on Robotics and Automation. May 16-21, 2016. Stockholm, Sweden. IEEE Xplore, June 9, 2016. doi: 10.1109/ICRA.2016.7487222.
Meeting: S. Sarker et al. The first autonomously controlled capsule robot for colon exploration. Digestive Disease Week 2017. May 7-9, 2017. Chicago, Ill.