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September 29, 2008

Multi-part self assembling stomach robot and nanotubes for better neural implants


By using magnetic links between capsules, researchers hope to build a snake-like robot that can self-assemble inside a patient’s stomach.
Credit: ETH Zurich


There were two advances that accelerate the integration of humans with electronic and robotic devices:

1. Modules that self-assemble inside the stomach could perform more-sophisticated diagnosis and treatment.

A collaboration of researchers from Italy, France, Switzerland, and Spain, called ARES, is testing a way for multiple capsules to automatically snap together. Each would be swallowed individually before assembling into a more complex device once safely in the stomach.

The ultimate goal is for each capsule to perform a different task: one for imaging, one for power, one to take samples, and so on. Once inside the stomach, the capsules would link together, creating a snake-like device that could slide through the intestines, performing more-complex tasks than those performed by a single capsule or several free-floating ones.

"Instead of having a single capsule, we propose a modular approach where each of the capsules could have different functionalities," says Zoltán Nagy, a researcher at the Swiss Federal Institute of Technology (ETH), in Zurich, and a member of the ARES project. "Before we can actually talk about such complex robots inside the stomach, we need to solve the fundamental problem of self-assembly. Our work suggests one [way that] this can be done robustly," says Nagy.

"One of the main constraints [of the swallowable imaging capsule] is the battery," says Milan Dodig, a gastroenterologist at Cleveland Clinic, who uses the device to treat his patients. "It takes almost 60 percent of the volume of the capsule; it's not steerable [and] can still miss stuff. The angle of the images is also limiting, and you can't see the complete [intestine]."



In these scanning electron microscope images, electrodes coated with carbon nanotubes, like the one on the right, are more conductive and better at interfacing with nervous tissue. The electrode on the left is bare.
Credit: Edward Keefer


2. researchers at the University of Texas are developing electrodes that are more efficient at both sending and receiving electrical stimuli. These electrodes, which are coated with carbon nanotubes, could lead to neural implants that monitor how they affect the neurons that they stimulate, conserving battery life and reducing side effects.







Pancrazio says that the nanotube coating might enable researchers to make smaller electrodes that cause fewer side effects. Using conventional electrodes for deep-brain stimulation, Pancrazio says, "you end up stimulating not only the area of interest but also other regions, leading to speech dysfunction and other problems." The ideal electrode would be small enough to interact with only a single neuron. But when electrodes are miniaturized, their impedance increases and their performance decreases. Electrodes coated in carbon nanotubes might be more amenable to miniaturization.

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