Microrobots Assist in Medical Operations and Drug Delivery

A team of researchers at EPFL and ETHZ have designed a new technique for constructing microrobots that can be used in the body to provide drugs and also perform a number of other medical operations.

Over the past few years, scientists around the globe have been researching methods to use miniature robots to help enhance the treatment of various types of diseases. The robots are designed in a manner that allows them to enter the human body, in order to deliver drugs at certain locations or perform specific operations like cleaning up clogged arteries. These robots can optimize medicine by replacing invasive often complicated surgeries.

Selman Sakar, a scientist from EPFL, collaborated with Hen-Wei Huang and Bradley Nelson at ETHZ to design a versatile and uncomplicated method to build robots that are bio-inspired and to engineer them with advanced features. A platform to analyze various robot designs and to study different modes of locomotion was created by the researchers. Nature Communications published their work, which produced complicated reconfigurable microrobots that can be designed with high throughput. They succeeded in building an integrated manipulation platform that has the ability to remotely control the robots’ mobility with electromagnetic fields, causing them to shape-shift using heat.

A Robot that Looks and Moves like a Bacterium

These microrobots are flexible, motor-less and soft unlike other conventional robots. They are designed using magnetic nanoparticles and biocompatible hydrogel. The nanoparticles perform two functions; they provide the microrobots with shape during the production process, and enable them to swim and move when an electromagnetic field is applied.

There are various steps involved in building one of these microrobots. Initally, the nanoparticles are positioned inside layers of a biocompatible hydrogel. The second step involves the application of an electromagnetic field to align the nanoparticles at different parts of the robot, which is followed by a polymerization step to “solidify” the hydrogel. Then, the robot folds in specific ways when placed in water, depending on the orientation of the nanoparticles inside the gel, resulting in the formation of the overall 3D architecture of the microrobot.

After creating the final shape, the robot is exposed to an electromagnetic field to make it swim. The robot changes shape and “unfolds” when it is heated. This fabrication approach enabled the scientists to build microrobots that duplicated the bacterium that causes sleeping sickness, also referred to as African trypanosomiasis. This specific bacterium uses a flagellum for propulsion, but shields it after entering a person’s bloodstream as a survival mechanism.

The researchers analyzed various microrobot designs to create a microrobot that mimics this behavior. The prototype robot presented in this work contains a bacterium-like flagellum that allows it to swim. While being heated with a laser, the flagellum tends to wrap around the robot’s body and is eventually “hidden”.

A Better Understanding of How Bacteria Behave

We show that both a bacterium’s body and its flagellum play an important role in its movement. Our new production method lets us test an array of shapes and combinations to obtain the best motion capability for a given task. Our research also provides valuable insight into how bacteria move inside the human body and adapt to changes in their microenvironment. There are many factors we have to take into account. For instance, we have to make sure that the microrobots won’t cause any side-effects in patients.

Selman Sakar, Scientist, EPFL

These microrobots are still under development.

The other scientists who have contributed in this work include Andrew Petruska and Salvador Pane.