Micromachines Discover Autonomous Synchronization: A Leap in Robotics

Like waves sweeping through tiny stadium crowds, microscopic machines engineered by Cornell researchers can autonomously synchronize their movements. This groundbreaking development opens new possibilities for the utilization of microrobots in various applications, including drug delivery, chemical mixing, and environmental remediation.

This innovative research, highlighted in a study published on November 27, 2024, in Science Robotics, represents the first demonstration of synchronization in microscopic machines equipped with complementary metal-oxide-semiconductor oscillators. Co-senior authors Alyssa Apsel, the IBM Professor of Engineering and director of the School of Electrical and Computer Engineering, and Itai Cohen, professor of physics in the College of Arts and Sciences and chair of the Department of Design Tech, lead this remarkable study.

Mechanism of Synchronization

The micromachines achieve coordination by exchanging electronic pulses, allowing the entire system to align with the fastest oscillator. Each machine is equipped with a bending paddle actuator that is merely 7 nanometers thick, bending similarly to the motion of a person standing and sitting in unison during a stadium wave.

“The oscillators operate at very low power—sub-nanowatt—while maintaining low complexity,” explained Apsel. “We are crafting local timing systems that can communicate with one another, which results in collective global behaviors. This approach proves ideal for microscale machines that lack the necessary power, capability, or space to be connected via long-distance wiring.”

Decentralized Synchronization Technique

The synchronization mechanism leverages a pulsed-coupling technique whereby oscillators send periodic electronic signals to adjust the timing of neighboring machines, effectively aligning their movements without requiring centralized control. This strategy draws inspiration from earlier studies on coupled oscillator systems, particularly work by mathematicians at Cornell who developed theoretical frameworks analyzing phenomena like fireflies flashing in unison or heart cells beating synchronously.

Resilience in Coordination

“This decentralized approach allows the system to self-correct and maintain synchronization even when conditions change or external disturbances occur,” stated Milad Taghavi, Ph.D. ’21, who co-led the research with Wei Wang, Ph.D. ’23.

Importantly, if a group becomes disconnected, each subgroup can still synchronize independently. When these groups eventually reconnect, the shared pulses enable seamless reestablishment of synchronization.

Scalability and Future Applications

The researchers achieved successful synchronization of arrays comprising up to 16 micromachines, tested in both linear and two-dimensional configurations. They noted that minimal adjustments would facilitate scaling to larger networks, which paves the way for coordinating increasingly complex microrobot swarms.

These advancements enable potential applications such as fluidic transport for drug delivery, chemical mixing, environmental cleanup, and collaborative construction at the microscale. “It also opens avenues for developing elastronic materials where electronics are embedded in each material element, creating emergent behaviors unattainable in natural systems,” Cohen added.

Future Prospects

Apsel expressed excitement for ongoing research efforts concerning micromachines, which may include projects involving coordinated microrobots designed to mimic inchworms or even micromachines that can divide into multiple autonomous entities.

“Engineers have made significant strides in creating tiny machines capable of movement and environmental sensing,” said Apsel. “However, finding elegant strategies to achieve collective operation remains a challenge. This research demonstrates how concepts from biology and nature can be employed to realize collective behaviors.”