Using a new way to wirelessly deliver power and instructions through organic tissue, researchers create a simple robot that could one day perform precise medical operations.

Researchers at Stanford this week reported that they have built a tiny computer chip that can theoretically "swim" through a person's bloodstream to deliver medicine, guide catheters, and perform other precise medical operations.

The little microchip measures just 3-by-4 millimeters, receives power and directions wirelessly, and uses electromagnetic induction for locomotion through fluids, according to the Stanford Daily.

The team, led by Stanford electrical engineering professor Ada Poon, had several challenges in developing the chip, which works by integrating some new technologies and building on Poon's previous research.

For example, when the electrical engineering researchers behind the project decided that they couldn't build an electrical motor small enough for an implanted device, they developed a means of using electromagnetic induction to slowly move the chip through fluids towards a target.

Poon, who presented the research at the International Solid-State Circuits Conference (ISSCC) on Tuesday, said her team also built on a previous discovery about how to get high-frequency wireless signals to transmit through organic tissue. Because higher frequency signals can be processed by smaller receiving antennae, this enabled them to deliver power and remote control orders to an implanted chip.

"The original research for this happened in the 1960s," Poon told the Stanford Daily. "Then, in the 1980s and 1990s, circuit designers just took these results, and they decided these circuits only worked around 10 megahertz."

The Stanford professor set out to challenge those assumptions several years ago, publishing the breakthrough that now enables wireless transmission to the team's current device back in 2009.

Other technologies developed for the project included a low-power wireless data transmission link, according to the Daily.

Poon said that in the near future the device could be attached to the tips of catheter tubes to help guide them. Other, more longer range ideas, like equipping the chips with sensors and sending them through coronary arteries to detect irregularities, would require the creation of a two-way signaling system on the devices as well as better control and movement mechanisms.

"If we really want to make it a robust system, we have to add a feedback system," she said.

Poon's team is exploring mechanical methods for improving health care via tiny implants, but another group of researchers on the opposite coast that comes at the problem from an entirely different direction.

A Different Approach

Just this past week, Harvard scientists said they had developed a cell-sniffing nanorobot that could potentially deliver payloads of drug molecules to cancer-stricken areas of a person's body.

The researchers said last Friday in a peer-reviewed study that they used their nanobots to deliver antibodies to lymphoma, leukemia, and other types of cancer cells, succeeding in halting their growth.

But exceedingly tiny nanobots deployed by Shawn Douglas, Ido Bachelet, and George Church of the Harvard Medical School's Wyss Institute for Biologically Inspired Engineering and Department of Genetics are not precisely the constructs one imagines when thinking of large robotsor even the comparatively big one built by Poon and her colleagues.

Instead of being made of metal, plastic, and circuitry, the Harvard team's nanorobots were created using "DNA origami," or "folding" DNA chains to form a barrel-shaped container for a payload of cancer antibodies.

The researchers targeted their payload-carrying nanobots using aptamers, molecule strands that can be engineered to "recognize" specific types of cells like cancer cells, according to an abstract of the study.

When the aptamers come into contact with cancer cells, they cause the nanobot's container to "unlock" and spill out the antibodies contained within.

In two separate experimental settings involving cell-signaling stimulation in tissue culture, the researchers loaded their barrel-shaped nanobots with antibody fragments for release at targeted sites when the aptamer-based sniffer instructed the devices to do so.

"We've been working on figuring out how to build different shapes using DNA over the past several years, and other researchers have used antibodies as therapeutics, in order to manipulate cell signalling, and yet others have demonstrated that aptamers can be used to target cancer cell types," Douglas, the study's lead author, told the BBC.

"The novel part is really integrating all those different pieces and putting them together in a single device that works," he said.

Douglas told the BBC that constructing the nanobots out of DNA made them more likely to be able to travel through our bodies safely without being rejected or harming us. He said the team was now working on optimizing the devices and building "a great many of them" for animal testing.