The key to the new platform is the integration of three functions on a scale measured in tens of micrometres. Each robot carries a temperature sensor, a programmable CMOS control circuit and arrays of electrochemical actuators that beat like biological cilia. The actuators are built from a titanium–palladium stack that bends when voltage is applied, driving ions into and out of the palladium layer and causing controlled bending at engineered hinges. Because the cilia are hinged, with two rigid panels connected by rotational joints, their beat cycle can be programmed to break the time-reversal symmetry that governs fluid motion at low Reynolds number. At microscopic scales, where viscosity dominates over inertia, fluid flows are reversible unless the stroke and the recovery stroke differ in shape, a constraint famously articulated in Lighthill’s analysis of flagellar hydrodynamics. The hinged design allows the robots to sweep the fluid with a fast, extended stroke and a slow, folded recovery, producing net pumping in a chosen direction.

Powering and controlling such tiny machines is a formidable engineering challenge, and the team solved it with microscale photovoltaic regions that convert incident laser light at 635 nanometres into electrical current for both the logic and the actuators. The binary sensing circuit switches its output phase configuration at threshold temperatures of 26 and 30 degrees Celsius, and can deliver actuation frequencies ranging from 0.4 to 12.8 hertz, with 1.6 hertz used for cilium beating in the reported demonstrations. The photovoltaic supply generates currents of roughly 0.78 microamperes at one sun of illumination, rising to about 4.8 microamperes at ten suns, enough to run the circuit and drive the cilia without any tether. This architecture builds on earlier work from the same collaboration, including electronically integrated mass-manufactured microscopic robots, cilia metasurfaces for programmable microfluidic manipulation, and microscopic robots with onboard digital control, but it adds something those systems lacked: a genuine sensory loop in which the robot’s action depends on what it measures.

The researchers demonstrated three distinct temperature-responsive modalities, each producing a different coupling between robot behaviour and environmental cues. The first is binary sensing, in which the onboard sensor acts as a threshold detector. Below the threshold the cilia pump in one direction; above it, the circuit reconfigures the wiring to the actuators and the pumping reverses. The team showed that this simple switch can reverse unidirectional flow, reverse the rotation of a single vortex, or reverse both vortices in a symmetric counter-rotating pair, all in response to nothing more than the ambient temperature crossing a set point. Because the flow patterns are generated by arrays of individually wired cilia, the same sensing principle can be routed into dramatically different hydrodynamic outcomes simply by changing how the circuit output is distributed across the array.

The second modality replaces the sharp threshold with continuous sensing, implemented using pulse-coupled oscillator circuits built from dynamic-leakage-suppression logic gates. In this scheme, the oscillation frequency of the onboard circuit depends on temperature through the exponential dependence of subthreshold leakage currents, so the beat frequency of the cilia rises smoothly as the fluid warms. The pumping speed therefore tracks temperature continuously rather than switching between two states. The oscillator architecture also supports synchronisation: coupling pulses from a designated leader oscillator advance the follower until the two lock with a fixed phase offset, a mechanism related to the pulse-coupled designs previously used for coordinating autonomous microscopic machines through local electronic pulses. This phase-locking provides a route to coordinated actuation across a cilia array without any central controller.

The third modality exploits spatial temperature gradients rather than absolute temperature. Using a scalable ultra-low-power temperature gradient sensor based on pulse-coupled oscillators, the robot determines which side of its body is warmer and aligns its pumping accordingly. When the imposed gradient is reversed, the leader and follower roles in the oscillator network exchange, and the pumping direction flips. The result is a microscopic machine that orients its fluid-mechanical output along the local thermal landscape, in loose analogy to the way ciliated protists orient their swimming relative to environmental cues. Together, the three modalities, threshold switching, continuous modulation and gradient alignment, form a toolkit for programming how a microrobot’s behaviour responds to its surroundings.

The most striking demonstration is the closing of the loop. Because the cilia-driven flows move fluid around, they transport heat, and the team showed that a collective array of cilia can actively reshape the local thermal field. In their experiments, unidirectional pumping advected fluid from a cooler region towards a hotter region, flattening the temperature gradient that the sensors were measuring. As the temperature field changed, the oscillator frequencies shifted, which in turn altered the pumping, which further modified the thermal field. The researchers modelled this feedback with a reduced two-dimensional description of thermally advected flow and quantified it through a thermal stretching length that grows cycle by cycle, fitting the dynamics with an exponential law. The system thus exhibits a genuine closed-loop interaction among sensing, actuation and environment, the microscopic analogue of an organism modifying its own habitat.

The experimental platform itself is a tour de force of integration. The devices were fabricated at the Cornell NanoScale Facility, with the CMOS circuits exposed by etching the top dielectric, then interconnected with titanium–platinum leads, re-encapsulated in silicon dioxide, shielded with a grounded layer, and finally released with an aluminium nitride sacrificial layer before the titanium–palladium actuator stack and rigid panels were added. Fluid temperatures were controlled with a hotplate and characterised by infrared thermography on dry samples, which showed a uniform region with a spatial standard deviation of about 0.11 degrees Celsius and a gradient region of roughly 0.5 degrees Celsius per millimetre; in liquid, where phosphate-buffered saline strongly absorbs mid-infrared radiation, the team used a micro-thermocouple instead. Flow fields were measured with particle image velocimetry and compared against three-dimensional hydrodynamic simulations of the beating cilia, validating the theoretical model of the two-hinged kinematics.

The implications reach well beyond the laboratory demonstration. Artificial cilia that sense and respond to their environment could regulate temperature and chemical gradients in lab-on-chip systems, create fluid microhabitats for recruiting cells or controlling microbiomes in biomedical contexts, and serve as building blocks for emergent collective behaviours in swarms of autonomous micromachines. The theoretical framing, developed with physicists studying non-reciprocal phase transitions and adaptive active solids, suggests that populations of such robots could self-organise into patterns no single robot is programmed to produce, much as bacterial colonies generate large-scale spiral waves from local interactions. Because the platform is built with standard CMOS processes and mass-manufacturable techniques, scaling to larger and more capable microrobotic collectives appears feasible. The work was supported primarily by the National Science Foundation and the Army Research Office, with additional support from the Kavli Institute at Cornell and Westlake University, and the team has filed patent applications covering the actuators and control electronics.

What makes this advance conceptually important is the shift from open-loop microrobots, which execute fixed motions, to machines that participate in a dynamic dialogue with their world. In nature, the coupling between organism behaviour and environmental modification underlies nest construction, swarm thermoregulation and microbiome recruitment; until now, engineered microrobots could sense or act, but rarely both in a feedback loop. By embedding thermal sensing, programmable logic and ciliary actuation on a single chiplet smaller than a grain of salt, the Cornell-led team has created the first microscopic robotic platform in which the environment is not merely a medium the robot moves through but a variable the robot actively regulates. As the researchers and their collaborators refine the sensing modalities and extend them to chemical and mechanical cues, the boundary between living, environment-shaping matter and engineered machines at the microscale looks set to blur further.

Subject of Research: Microscopic robots with onboard sensing, logic and cilia actuators that couple their behaviour to thermal environmental cues in a closed loop

Article Title: Microscopic robots that sense and reshape their environment

Article References: Wang, W., Zhang, J., Chaudhari, P., Shim, K., Severn, J., Zheng, C., Liang, Z., Ji, Y., Pelster, J., Griniasty, I., Seara, D., Vitelli, V., Lauga, E., Apsel, A., & Cohen, I. (2026). Microscopic robots that sense and reshape their environment. Nature Electronics. https://doi.org/10.1038/s41928-026-01709-x

Image Credits: AI Generated

DOI: 10.1038/s41928-026-01709-x

Keywords: microrobotics, artificial cilia, CMOS, electrochemical actuators, temperature sensing, microfluidics, closed-loop control, NEMS, collective behaviour, thermal regulation, Cornell University, Nature Electronics