The gastrointestinal (GI) tract is a collection of organs and structures inside the bodies of humans and other animals that is responsible for the digestion of food, the absorption of nutrients and the expulsion of waste. Its underlying parts include the mouth, esophagus, stomach, intestines, rectum and anus.

Over the past decades, the incidence of cancer in the GI tract and some other conditions affecting the digestive system has risen substantially. Existing approaches to diagnose and treat GI cancers rely on endoscopy, a medical procedure that entails the inspection of internal organs via a flexible tube with an embedded camera (i.e., endoscope), which is inserted into the body through the anus, mouth or a small incision.

In addition to being highly uncomfortable for patients, endoscopy often fails to reach regions that are deep into the GI tract or are difficult to access due to the body's natural configuration. Some biomedical engineers have thus been trying to devise alternative systems that could inspect parts of the digestive system more effectively, while causing patients minimal discomfort.

A team of researchers at the University of Macau in China recently developed new soft magnetic robots that can climb inverted surfaces and move in complex environments, which could allow them to deliver drugs to specific locations in the GI tract.

These robots, introduced in a paper published in the International Journal of Extreme Manufacturing, were designed to mimic the movements of the golden wheel spider, an arachnid that can move on various terrains by performing unique rolling motions.

"In recent years, the rising incidence of GI cancer has triggered an urgent need for effective early intervention strategies," wrote Ruomeng Xu, Xianli Wang, and their colleagues in their paper. "Traditional endoscopic techniques often cause patient discomfort, and it is difficult to navigate deep regions of complex organ structures. This work proposes a kind of bio-inspired magnetic soft robot (BMSR) to address these challenges."

The researchers fabricated their robots using flexible and deformable materials, as opposed to rigid mechanical parts. These materials are less likely to damage tissue inside the body, while also causing less discomfort to patients as they navigate the GI tract.

"The design of the BMSRs is inspired by the rolling motion of the golden wheel spider," wrote the authors. "Two six-degree-of-freedom (6-DOF) robotic arms are used, where one arm is responsible for real-time manipulation of the BMSRs, and the other is dedicated to monitoring their status."

The newly developed BMSRs can be controlled via a magnetic field that is applied from outside the body, guiding their movements without the need for onboard motors. Due to their unique design, the robots can climb inclined surfaces at any angle, which could be highly advantageous for the navigation of the intestines and digestive tract.

"Through the powerful output force, the BMSRs can overcome the mobility barrier induced by different human organs, including mucus, folds, and height differences of up to 8 cm," wrote the researchers. "Such an exceptional mobility enables the BMSRs to deliver drugs in the targeted complex GI environment. Moreover, in combination with an endoscope, it provides real-time visual feedback for precise navigation."

To assess the ability of their robots to navigate the GI tract, the team tested them in preliminary experiments, where they moved them inside parts of the GI tract of deceased animals that share common features with humans. They found that the robots successfully delivered drugs to target locations, without damaging tissues.

"In vitro animal experiments validate the feasibility of BMSRs, paving a way for their usage in minimally invasive GI treatment," wrote the authors. "This work advances the potential applications of magnetic soft robots in the biomedical field."

In the future, the BMSRs introduced by the researchers could be improved further and tested in live animals. If they prove to be safe and biocompatible, which means that they can be inserted into the body without causing harmful or undesired reactions, they could then be tested in human clinical trials, potentially offering an alternative and less-invasive route for the treatment of GI cancers.