‘Robotic sperm’ controlled with magnets


Engineers have been successful in building a sperm-like robot that is able to be controlled with magnets.

It is a simple design with a flexible body and a head coated with metal, with a length of about six times that of a human sperm.

The team used a magnetic field which is no stronger than that of a fridge magnet to move the robot forward and steer it to a predetermined point. Their findings have been published in Applied Physics Letters and they are hoping that it will be useful in manufacturing and medical applications.

Like some bacteria, sperm makes use of a whip-like ‘flagellum’ as a means to propel itself though liquid. Other studies in this field have included the use of a magnetic tail coupled with a red blood cell, or the control of real sperm by driving it through metal microtubes.

The new device is manufactured from a flexible, but strong polymer, with a metal layer which has been painted onto the head with the use of electron beam evaporation methods.

The metal section is forced into different directions once the device is placed into a field that is moving. This is produced by the coils of the electromagnet.

By changing the current within the coils the magnetic head is moved in a specific direction by flapping the tail. The robot does not compete with human sperm for speed. The device moves at around 0.5 body lengths each second, compared to human sperm which is able to move several times its body length in the same time.

One of the scientists involved in the design, Dr Misra, indicated that it is possible to accurately steer the device, by an adjustment of the magnetic field on a computer.

Dr Misra stated that the device is suitable where precise locations need to be reached, such as in vitro fertilisation. The little robots would also be useful during nano-manufacturing procedures.

For their ideas to become functional, it will be necessary for the methods to be tested in more advanced environments. The scientists are in the process of doing the more advanced tests, and are working on making the device smaller and boosting its speed.

Dr Matthew Baker from the Victor Chang Cardiac Research Institute in Sydney, said that the device was ‘very cool’, but is not a robot in the sense that many people would imagine. He said it is simply a piece of metal, but the smart part of the device is the small, tuneable, oscillating magnetic field.

Dr Islam Khalil, the first author of this study, says the outsourcing of power and the navigation is what allows the device to be so small. He said that the advancement of technology demands smaller products which make it hard to assemble objects on micro- and nano-scales.

He added that the device, called MagnetoSperm, could be used to manipulate and assemble objects of this size by using an external magnetic field source for the control of its movement.

Video Credit: University of Twente


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