On a crisp fall evening in 2006, Dr. Sylvain Martel held his breath as a technician slipped an anesthetized pig into a whirling fMRI machine. His eyes stared intently at a computer screen, which showed a magnetic bead hovering inside the pigs delicate blood vessels. The tension in the room was palpable.
Suddenly, the bead jumped to life, hopping effortlessly down the vessel like a microsubmarineheading to its next target destination. The team erupted in cheers.
Martel and his team were testing a new way to remotely steer tiny objects inside a living animal by manipulating the magnetic forces of the machine. And for the first time, it worked.
Scientists and writers have long dreamed of tiny robots that navigate the bodys vast circulatory system, like space explorers surveying the galaxies and their inhabitants. The potentials are many: tiny medical microbots could, for example, shuttle radioactive drugs to cancer clusters, perform surgeries inside the body, or clear out blood clots lodged deep inside the heart or brain.
The dream is the Fantastic Voyage, but with bots instead of people, says roboticist Dr. Bradley Nelson at ETH Zurich, referencing a classic science fiction movie wherein a team of people are shrunken down and travel through a persons bloodstream to perform brain surgery on a moribund intelligence agent.
For now, medical microbots are still mostly fictional, though thats set to change within the decade. Writing in Nature this week, Drs. Mariana Medina-Snchez and Oliver G. Schmidt at the Leibniz IFW in Dresden, Germany turned away from the big screen to nanoengineering labs, setting out priorities and realistic tests to bring these tiny surgeons to life.
Medical microbots are part of the medical fields journey into miniaturization. Back in 2001, an Israeli company introduced the PillCam, a candy-sized plastic capsule that harbored a camera, batteries and wireless transmission machinery. While traveling down the alimentary canal, the PillCam periodically beamed back images wirelessly, offering a more sensitive and less toxic diagnostic measure than traditional endoscopy or X-ray imaging.
Size wise, the PillCam is gigantic for an ideal microbot, making it only suitable for the relatively wide tubing of our digestive system. The pill was also passive, unable to linger at interesting locations for a more detailed survey.
A true medical microbot must propel and steer itself through an intricate network of fluid-filled tubes to tissues deep inside the body, explains Martel.
The body, unfortunately, is rather hostile to outsiders. Microbots have to be able to survive corrosive gastric juices and paddle upstream in the blood flow without the convenience of battery-powered motors.
Labs around the world are figuring out clever alternatives to the power problem. One idea is to create what are essentially chemical rockets: cylindrical microbots loaded with fueloften a metal or other catalystthat reacts with gastric juices or other liquids to expel bubbles from the back of the tube.
These motors are hard to control, say Medina-Snchez and Schmidt. We can roughly control their direction using chemical gradients, but they dont have enough endurance and efficacy. Designing non-toxic fuels based on the bodys supplysugar, urea, or other physiological fluidsis also hard.
An arguably better alternative is metallic physical motors that can be propelled by changes in magnetic fields. Martel, as demonstrated with his bead-in-a-pig experiment, was among the first to explore these propellers.
The MRI machine is perfect for steering and imaging metallic microbot prototypes, explains Martel. The machine has several sets of magnetic coils: the main set magnetizes the microbot after it is injected into the bloodstream through a catheter. Then, by manipulating the gradient coils of the MRI, we can generate weak magnetic fields to nudge the microbot down blood vessels or other biological tubing.
In subsequent experiments, Martel made iron-cobalt nanoparticles coated with a cancer drug and injected the tiny soldiers into rabbits. Using a computer program to automatically change the magnetic field, his team steered the bots to the target location. Although there were no tumors to kill in that particular study, Martel says similar designs could prove useful for liver cancers and other tumors with relatively large vessels.
Why not smaller vessels? The problem is, again, power. Martel was only able to shrink the bot down to a few hundred micrometersanything smaller required magnetic gradients so large that they disrupted neuronal firing in the brain.
A more elegant solution is using biological motors that already exist in nature. Bacteria and sperm are both armed with whip-like tails that propel them naturally through the bodys convoluted tunnels and cavities to perform biological reactions.
By combining mechanical bits with biological bits, the two components could give each other a boost when one is faltering.
An example is the spermbot. Schmidt previously designed tiny metal helices that wrap around lazy sperm, giving them a mobility boost to reach the egg. Sperm could also be loaded with drugs, linked to a magnetic microstructure to treat cancers in the reproductive tract.
Then there are specialized groups of bacteria called MC-1 that align themselves with Earths magnetic field. By generating a very weak fieldjust enough to overcome Earthsscientists can point the bacterias internal compass towards a new goal such as cancer.
Unfortunately, drug-tagged MC-1 bacteria only survive in warm blood for roughly 40 minutes, and most arent strong enough to swim against the bloodstream. Martel envisions a hybrid system made of bacteria and fat-based bubbles. The bubbles, loaded with magnetic particles and bacteria, would be guided down larger blood vessels using strong magnetic fields until they smack into narrower ones. Upon impact, the bubbles would pop and release the swarms of bacteria to finish their journey, guided by weaker magnetic fields.
While scientists have plenty of ideas for propellers, a main hurdle is tracking the microbots once theyre released into the body.
Combining different types of imaging techniques may be the way forward. Ultrasound, MRI and infrared are all too slow to follow microbots operating deep within the body by themselves. However, combining light, sound, and electromagnetic waves could increase resolution and sensitivity.
Ideally, an imaging method should be able to track micromotors 10 centimeters under the skin, in 3D and real-time, moving at minimum speeds of tens of micrometers per second,say Medina-Snchez and Schmidt.
Its a tall order, though theyre hopeful that cutting-edge optoacousticmethodscombining infrared and ultrasound imagingcould be good enough to track microbots within a few years.
Then theres the question of what to do with the bots after theyve finished their mission. Leaving them drifting inside the body could result in clots or other catastrophic side effects, such as metal poisoning. Driving the bots back to their starting point (mouth, eyes, and other natural orifices, for example) may be too tedious. Scientists are now exploring better options: expelling the bots naturallyor making them out of biodegradable materials.
The latter has another plus: if the materials are also sensitive to heat, pH, or other bodily factors, they can make autonomous biobots that operate without batteries. For example, scientists have already made little star-shaped grippers that close around tissues when exposed to heat. When placed around diseased organs or tissues, the grippers could perform on-site biopsies, offering a less invasive way to screen for colon cancers or monitor chronic inflammatory bowel disease.
The goal is a microbot that can sense, diagnose, and act autonomously, while people monitor it and retain control in case of malfunction, say Medina-Snchez and Schmidt.
The medical microbots fantastic voyage is just beginning.
All combinations of materials, microorganisms and microstructures need to be tested together for their behavior in animals first to ensure safety and function. Scientists are also waiting for regulators to catch up, and for clinicians to ponder new ways to deploy these new microbots in diagnostics and treatments.
But optimism is growing in the ever-expanding field.
With a coordinated push, microbots could usher in an era of non-invasive therapies within a decade, declare Medina-Snchez and Schmidt.
Banner image and video ("Self-Folding Thermo-Magnetically Responsive Soft Microgrippers) courtesy of ACS Applied Materials & Interfacesand licensedCC BY-NC.
Continue reading here:
Here Are the Microsurgeons That Will Soon Roam Our Bodies - Singularity Hub
- Micro Manufacturing - November 8th, 2009 [November 8th, 2009]
- Modeling and Simulation - November 8th, 2009 [November 8th, 2009]
- Electron Microscopy - November 8th, 2009 [November 8th, 2009]
- Metrology - November 8th, 2009 [November 8th, 2009]
- Calibration Services - November 8th, 2009 [November 8th, 2009]
- Micro Engineering - November 8th, 2009 [November 8th, 2009]
- Nanotechnology - November 8th, 2009 [November 8th, 2009]
- Creating nano-structures from the bottom up - April 25th, 2012 [April 25th, 2012]
- Wichita State hands out new round of high-tech grants - April 25th, 2012 [April 25th, 2012]
- URI Engineering Student Develops Self Healing Concrete - Video - May 4th, 2012 [May 4th, 2012]
- NYS Senator Joseph A. Griffo Visits Clarkson University Nanoengineering - May 4th, 2012 [May 4th, 2012]
- Nano-subs built to grab and move oil spills - May 5th, 2012 [May 5th, 2012]
- Video: N.Y. lab creating jobs with nano-technology - May 5th, 2012 [May 5th, 2012]
- Nano-Subs Grab and Move Oil Spills - May 5th, 2012 [May 5th, 2012]
- University of Toronto Engineering Welcomes New NSERC Chair in Multidisciplinary Design - May 5th, 2012 [May 5th, 2012]
- Nano-Sensors for Explosive Detection -- University Collaboration Addresses Challenges in Explosive Detection - May 10th, 2012 [May 10th, 2012]
- Obama, Cuomo touring Nano college - May 10th, 2012 [May 10th, 2012]
- Obama, Cuomo bond over vision of economic future - May 10th, 2012 [May 10th, 2012]
- Kids visit Nano College after Obama - May 10th, 2012 [May 10th, 2012]
- Zyvex Technologies and ENVE Composites Introduce the World's First Nano-Enhanced Carbon Fiber ... - May 16th, 2012 [May 16th, 2012]
- Listen Now - May 16th, 2012 [May 16th, 2012]
- To Czech Industry, Everything Is Nano - May 23rd, 2012 [May 23rd, 2012]
- Availability of hydrogen controls chemical structure of graphene oxide - May 23rd, 2012 [May 23rd, 2012]
- Hydrogen Controls Chemical Structure of Graphene Oxide - May 23rd, 2012 [May 23rd, 2012]
- Shocking Technologies Raises Additional $10.5 Million From Circuit Protection Leader Littelfuse - May 23rd, 2012 [May 23rd, 2012]
- Nano-structured polymer-based materials from scrap - May 25th, 2012 [May 25th, 2012]
- Journal Tips from the American Institute of Physics: May 24, 2012 - May 25th, 2012 [May 25th, 2012]
- Synthetic nano-waste does not disappear - May 25th, 2012 [May 25th, 2012]
- Attacks on Nuclear and Nano Science - May 29th, 2012 [May 29th, 2012]
- Graphene quantum dots and nano-ribbons cleaved from graphene sheets - May 30th, 2012 [May 30th, 2012]
- Girls Inc.and SEFCU to provide internships at Nano College - May 31st, 2012 [May 31st, 2012]
- Nano technology improves health field - June 2nd, 2012 [June 2nd, 2012]
- Tiny satellites will use Kinect to dock with one another - June 4th, 2012 [June 4th, 2012]
- New nano-research leads to sensors that detect contaminants in water - June 6th, 2012 [June 6th, 2012]
- Editorial: State sets example on economy, bipartisanship - June 6th, 2012 [June 6th, 2012]
- MP girl ‘Gargi Pare’ brings laurels to State - June 6th, 2012 [June 6th, 2012]
- Element Six and Harvard University Collaboration on Nano-Engineered Synthetic Diamond Sets a New Quantum Information ... - June 8th, 2012 [June 8th, 2012]
- Business at a glance - June 10th, 2012 [June 10th, 2012]
- Inter American University of Puerto Rico Chooses Nanoprofessor as Foundation for New Nanoscience Education Program - June 11th, 2012 [June 11th, 2012]
- Nanoparticles found in moon glass bubbles explain weird lunar soil behaviour - June 13th, 2012 [June 13th, 2012]
- Nanoparticles found in moon glass bubbles explain weird lunar soil behavior - June 13th, 2012 [June 13th, 2012]
- Nanoparticles can solve mystery of Moon's topsoil - June 13th, 2012 [June 13th, 2012]
- Nano-Technologies Extended to Coax - June 15th, 2012 [June 15th, 2012]
- Shocking Technologies Raises Additional $10.5M From Circuit Protection Leader Littelfuse - June 15th, 2012 [June 15th, 2012]
- NIT-T professor gets over Rs. 2.15 crore to stall erosion in pipes - June 18th, 2012 [June 18th, 2012]
- Northeastern University Nanomanufacturing Center Director Ahmed Busnaina to Present Webinar on “The Democratization of ... - June 19th, 2012 [June 19th, 2012]
- NIT Silchar convocation - June 19th, 2012 [June 19th, 2012]
- Research and Markets: Government Initiative and High R&D Activities Drive the Nanotechnology Market in India - June 19th, 2012 [June 19th, 2012]
- Scientist unlocks the quantum secrets of the moon's bizarre soil, which hangs suspended above the surface when touched - June 20th, 2012 [June 20th, 2012]
- Nano-infused paint can detect strain - June 22nd, 2012 [June 22nd, 2012]
- "Proceedings of the IEEE" Hosts Centennial Engineering Innovation Forum in DC to Unveil Advanced Technologies ... - June 22nd, 2012 [June 22nd, 2012]
- Nanotech paint can show stress and strain - June 22nd, 2012 [June 22nd, 2012]
- Tatas developing an under $ 20,000 electric car - June 22nd, 2012 [June 22nd, 2012]
- Now, nano-infused paint to detect strain in buildings, bridges and airplanes - June 22nd, 2012 [June 22nd, 2012]
- Nano-sandwich technique slims down solar cells, improves efficiency - June 26th, 2012 [June 26th, 2012]
- Team develops world's most powerful nanoscale microwave oscillators - June 26th, 2012 [June 26th, 2012]
- UCLA-led research team develops world's most powerful nanoscale microwave oscillators - June 26th, 2012 [June 26th, 2012]
- Research and Markets: MEMS, NANO and Smart Systems - Selected papers from the 2011 7th International Conference on ... - June 27th, 2012 [June 27th, 2012]
- A step toward minute factories that produce medicine inside the body - June 28th, 2012 [June 28th, 2012]
- Green feel for collaboration with China - June 28th, 2012 [June 28th, 2012]
- Fibrous Protein Nanocomposites Conference - June 28th, 2012 [June 28th, 2012]
- Going For Gold: The Brains Behind Team GB - July 4th, 2012 [July 4th, 2012]
- NANO Connect Offers International Perspective With South Korean Nanotechnology Education Leader - October 4th, 2012 [October 4th, 2012]
- Hardide appoints a Business Development Manager - October 4th, 2012 [October 4th, 2012]
- Regenerative Medicine Biotech Company, Eqalix, Names Scientific Advisory Board - October 9th, 2012 [October 9th, 2012]
- Quinn uses nanotechnology summit to praise Wheeling High School - October 9th, 2012 [October 9th, 2012]
- Cal Poly Licenses CubeSat Technology to Tyvak Nano-Satellite Systems - October 11th, 2012 [October 11th, 2012]
- Improving nanometer-scale manufacturing with infrared spectroscopy - October 11th, 2012 [October 11th, 2012]
- KYOCERA Introduces New Milling Cutters For CNC Machining Featuring Inserts with Proprietary MEGACOAT NANO Technology - October 16th, 2012 [October 16th, 2012]
- iFixit opens up the new iPod nano - October 16th, 2012 [October 16th, 2012]
- Call to assess safety of nano particles - October 16th, 2012 [October 16th, 2012]
- Special Program at SPE ANTEC® Mumbai Will Focus on Nano-Scale Carbonaceous Materials - October 16th, 2012 [October 16th, 2012]
- NUS launches Aerospace Systems initiative for engineering students - October 30th, 2012 [October 30th, 2012]
- Life After MESA - University of California, San Diego - Video - October 30th, 2012 [October 30th, 2012]
- Toulouse, capitale européenne des nanotechnologies du 16 au 20 septembre 2012. - Video - October 30th, 2012 [October 30th, 2012]
- Techno Frühstück - Correspondence of Heart and Beat - Video - October 30th, 2012 [October 30th, 2012]
- CVTC Engineering Programs Commercial - Video - October 30th, 2012 [October 30th, 2012]
- DISSECTED FROG - BIOLOGY LAB FOR NANO ENGINEERING - Video - October 30th, 2012 [October 30th, 2012]
- Renault looking to build an upmarket rival to the Tata Nano, but it will still be very cheap - December 5th, 2012 [December 5th, 2012]
- 'Nano' opens at Discovery Museums - December 8th, 2012 [December 8th, 2012]