By Ashini K Ekanayake
With the rapid development of society’s technological prowess, our capabilities regarding robotics grow ever stronger. Over time, these robots become automated and shrink in size, allowing them to become utilized for extremely specialized work. One example of this is how a team of researchers at the Georgia Institute of Technology has developed a tiny, 3D printed robot which can respond to vibrations. The robot will possess the ability to work in teams, similar to ants, and could potentially be used to repair injuries within the human bodies. The robots are designed to move by harnessing vibrations from sources such as piezoelectric actuators, ultrasound sources, or tiny speakers.
These teensy automatons, called “micro-bristle-bots” by the team due to how their legs look like bristles, consists of a piezoelectric actuator glued onto a polymer body. Researchers used a process called two-photon polymerization lithography (TPP) to 3D-print the bodies of the robots, some of which have four legs while others have six. TPP involves a monomer resin material being polymerized by striking it with an ultraviolet light to chemically develop the resin. Once this is complete, the remainder can be washed away, leaving the desired robotic structure. These piezoelectric actuators uses the material lead zirconate titanate (PZT), which vibrate when electric voltage is applied to them. As a result, these micro-bots could be used to power up onboard sensors when they are activated by external vibrations.
Due to the minute size of the robots, which is approximately 2 millimeters long, which is approximately the size of the world’s smallest ant. As a result, batteries are too small to fit inside the bot. Instead, the robot’s actuators generate vibrations from various sources, such as a piezoelectric shaker beneath the surface on which the robots move. The vibrations generated by the actuators move the bot’s springy legs up and down, propelling it forward at a speed controlled by the amplitude of the vibrations. Each robot can be designed to respond to different vibration frequencies depending on several factors These factors include, but are not limited to leg size, diameter, design, and overall geometry. The bots can move quite speedily, covering four times their own length in a second.
The researchers at the institute plan to continue working on the robots to add capabilities as well as to improve the current design process, which is quite time-consuming currently. The team is researching on methods to mass produce hundreds to thousands of robots at a time. One planned method is to incorporate steering by joining two slightly different micro-bristle-bots together, because each of the bots would respond to different vibration frequencies, the combination could be steered by varying the frequencies and amplitudes.
This function will allow for numerous other applications, which will inevitably be explored by the research team.