Nano-Bots: The Future of Miniaturized Robotics through 3D Nanofabrication

In the 1980s, the creation of micro-electro-mechanical systems (MEMS) sparked excitement among computer engineers. These devices, combining electrical and mechanical components at the microscale, offered the potential to build miniature robots.

The concept of scaling down robotic mechanisms to such small sizes was particularly intriguing due to the possibilities of achieving exceptional performance in speed and precision. However, the challenge lay in the limitations of microscale 3D manufacturing.

Fast forward almost 50 years, Ph.D. students Steven Man and Sukjun Kim, under the guidance of Mechanical Engineering Professor Sarah Bergbreiter, have pioneered a 3D printing process for constructing tiny Delta robots known as microDeltas. These microDeltas, significantly smaller in size compared to their larger counterparts used in industrial settings, hold promise for applications in micromanipulation, microassembly, minimally invasive surgeries, and wearable haptic devices.

Their research has been published in the journal Science Robotics.

Prior methods of creating robotic mechanisms at such small scales involved manual assembly and folding of microfabricated components.

Bergbreiter’s team introduced a 3D printing approach for microrobotics utilizing two-photon polymerization, an advanced nanofabrication technique where a focused laser solidifies photosensitive material with extreme precision. Subsequently, a thin metal layer is applied to enable electrical functionality in complex 3D geometries and actuators without the need for folding or manual assembly.

The microDelta robots, measuring 1.4 mm and 0.7 mm in height, stand out as the smallest and fastest Delta robots ever demonstrated. The researchers’ ability to test predictions made nearly 50 years ago was validated. Shrinking the robots led to improved precision to less than a micrometer, increased speed operating at frequencies over 1 kHz, and the capacity to launch a grain of salt—a projectile representing 7.4% of the robot’s total mass.

Bergbreiter commended Man for swiftly iterating through eight designs of the microDelta robots. This rapid progress was facilitated by the 3D design and printing approach, a stark contrast to previous time-consuming methods that could take weeks or months for design and fabrication.

“I am impressed by the rapid iterations of these designs by Steven and Sukjun. Moving forward, students can easily build on this work, leading to further enhancements,” Bergbreiter remarked.

Using the model established in this research, students can enhance desired metrics such as bandwidth, accuracy, and workspace by adjusting the robot’s design parameters, creating extensive arrays of microDeltas, or incorporating sensing capabilities for closed-loop operation.

Faculty members Zeynep Temel and Oliver Kroemer from the Robotic Institute are already leveraging arrays of larger Delta robots for intricate manipulation tasks. The compact size of microDelta robots opens up possibilities for densely packed arrays, enabling new capabilities at small scales for enhanced haptic feedback or previously unachievable micromanipulation tasks.

“The elimination of manual assembly offers significant advantages in terms of rapid fabrication and iterative design,” Bergbreiter added. “At larger scales, researchers can assemble robots using off-the-shelf motors and mechanisms. However, at these small scales, where creating and connecting tiny pieces is challenging, this new fabrication process proves immensely beneficial.”