Mobilizing Microbes

BU-Led Team to Engineer Robot-Assisted, Bacteria-Based Sensors

By Mark Dwortzan

ENG research will support the project's three main thrusts: programmed bacteria with engineered biomolecular sensors and synthetic gene networks, two-way communication between micro-bio-robots (MBRs) and chaperone robots, and swarms of MBRs supervised by chaperone robot systems.
ENG research will support the project's three main thrusts: programmed bacteria with engineered biomolecular sensors and synthetic gene networks, two-way communication between micro-bio-robots (MBRs) and chaperone robots, and swarms of MBRs supervised by chaperone robot systems.

At the bottom level, engineered bacteria interact among each other mechanically (through the surface they adhere to) and chemically (through diffusion). At the middle level, MBRs communicate among themselves and with the chaperone robots locally via light or chemical inducers. At the top level, the chaperone robots communicate among themselves and with a supervisor through wireless communication.
At the bottom level, engineered bacteria interact among each other mechanically (through the surface they adhere to) and chemically (through diffusion). At the middle level, MBRs communicate among themselves and with the chaperone robots locally via light or chemical inducers. At the top level, the chaperone robots communicate among themselves and with a supervisor through wireless communication.

Cheap, adaptable to extreme environments—and endowed with a natural ability to probe, analyze and modify their surroundings—microbiological organisms represent a promising  line of attack for everything from oil spill cleanup to chemical weapons detection. But harnessing this capability will require some complex technological enhancements. Major challenges include getting the microbes to sense, process and respond to specific stimuli; equipping them to communicate their findings; and coordinating them to take collective action in real-time.

Now a research team led by Professor James Collins (BME, MSE, SE) proposes to surmount these challenges through an unprecedented combination of expertise in synthetic biology, computer engineering, control systems and robotics.

The Office of Naval Research has awarded the team—which includes Assistant Professors Calin Belta (ME, SE) and Douglas Densmore (ECE) and leading researchers from Harvard University, MIT, Northeastern University and the University of Pennsylvania—with a highly competitive Multidisciplinary University Research Initiative grant of $7.5 million to pursue its project, “Utilizing Synthetic Biology to Create Programmable Micro-Bio-Robots,” over the next five years. The team’s goal is to develop technologies that enable swarms of microbiological organisms to execute desired tasks in a cohesive, efficient manner.

Toward that end, the researchers plan to genetically alter microbes to detect, analyze and respond to explosives, toxins, metals, salinity, pH, temperature, light and other environmental signals; assemble groups of these programmed microbes and support hardware into 10-100-micrometer-long hybrid “micro-bio-robots” (MBRs); and design 10-100-centimeter-long, powered “chaperone robots” that direct and monitor thousands of MBRs at close proximity and apprise human operators of their progress via wireless communication.

“The idea is to engineer living organisms—in this case bacteria—that respond to external stimuli in the environment,” Densmore explained. “In response, they will generate a fluorescent or chemical signal that can be measured by the chaperone robots, which can produce signals as well that the bacteria can detect, so you have a two-way communication system. Finally, the chaperone robots can also communicate with human users.”

Using techniques from synthetic biology, the researchers intend to modify bacterial DNA so that the cells can both sense and report on specific stimuli. For instance, the researchers may alter DNA within bacterial cells to produce a fluorescent protein that glows green in the presence of high pH, a signal that nearby chaperone robots can interpret and relay to human operators.

The College of Engineering contribution to this effort is substantial. Collins will work on DNA modification; Densmore will optimize selection of DNA sequences used to enable microbial cells to sense and indicate the presence of specific environmental signals; and Belta will participate in the design and assembly of MBRs and chaperone robots, and efforts to coordinate their activity.

“People have made robots that can respond to external stimuli, and synthetic biologists have made bacteria that can sense environmental conditions, but putting it all together in a highly coordinated and deterministic system is completely new,” said Densmore.

 

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