June 3, 2014
MagnetoSperm Robots Could One Day Be Used For In Vitro Fertilization
Brett Smith for redOrbit.com - Your Universe Online
Doctors looking to conduct procedures on a microscopic scale have developed sperm-inspired robots that can be manipulated through the use of weak oscillating magnetic fields, according to a new report in the journal Applied Physics Letters.
Measuring just over 320 microns in length, the tiny robots are comprised of a head covered in cobalt-nickel and an uncoated tail. When the robot is exposed to an oscillating field of weaker than 5 millitesla – around the strength of a refrigerator magnet – it creates a magnetic torque on its head, forcing its flagellum to oscillate and drive it forward. The scientists are then able to maneuver the robot by pointing the magnetic field at a specific location.
"Nature has designed efficient tools for locomotion at micro-scales. Our microrobots are either inspired from nature or directly use living micro-organisms such as magnetotactic bacteria and sperm cells for complex micro-manipulation and targeted therapy tasks," said study author Sarthak Misra, an associate professor of robotics at the University of Twente in The Netherlands.
The microrobot was developed by spin-coating a five-micron polymer layer onto a silicon support wafer. The cobalt-nickel layer was then applied to the head using electron beam evaporation.
"As technology progresses and many products get smaller, it becomes difficult to assemble objects on nano- and micro-scales," added Islam Khalil, an assistant professor of robotics at the German University in Cairo. "MagnetoSperm can be used to manipulate and assemble objects at these scales using an external source of magnetic field to control its motion."
Khalil said the MagnetoSperm robots could be used for in vitro fertilization, drug delivery, cell sorting and the clearing of blocked blood vessels. The study team said they are currently looking into scaling down the robots into even smaller sizes.
In December, a team of German scientists revealed a sperm-based microrobot that could function similarly to the MagnetoSperm.
According to a report from New Scientist, the system involves placing a bull sperm inside a nanotube. The scientists are then able to remotely control the movements of the sperm using magnetic fields. The speed of the sperm can be controlled be changing the temperature of its environment, the report said.
“The combination of a biological power source and a microdevice is a compelling approach to the development of new microrobotic devices with fascinating future application,” the study team wrote.
To create the biological-mechanical hybrid, the researchers made tiny iron and titanium tubes 50 microns long and 5 to 8 microns in diameter. The researchers then added the tubes to a fluid with thawed bull sperm. The tubes were made with one end slightly smaller than the other, allowing a sperm to swim into one end and become trapped with their flagella still able to move. Using magnetic fields, the team could then control the trapped sperm in much the same way a compass needle aligns with Earth’s magnetic field.
The researchers said sperm cells are an ideal delivery system because they are harmless to the human body, don’t need an external power source and can pass through viscous liquids.
Image 2 (below): MagnetoSperm performs a flagellated swim using weak oscillating magnetic fields. Credit: I.S.M. Khalil/GUC & S. Misra/U.Twente