David Gonzalez-Medrano

arXiv2026

Scalable reflective communication for microscopic electronics

Untethered microscopic electronic circuits hold the potential for extraordinary advances in many fields such as neural transmitting and distributed sensing. However, establishing uplink communications from the microscale back to the macroscopic world remains challenging; existing micro-transmitters are difficult to integrate with semiconductor processing. Here we surmount this obstacle, introducing a strategy for modulating backscattered photons based on the electrochromic polymer PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) that is scalable to micron-order sizes and manufacturable using standard parallelizable methods. Our devices, which we call SPOTs (submillimeter polymer optical transmitters), actuate at low voltages (< +/-1 V), switch in as fast as 10 {\mu}s, can run for millions of cycles, and operate seamlessly in electrolytes. We achieve this design by emphasizing architectural simplicity and mass-manufacturability rather than traditional metrics such as data rates or energy costs. As a demonstration, we develop SPOT-equipped temperature-sensitive photovoltaic-powered foundry-fabricated microchips and use them to wirelessly measure and transmit local temperatures. These results represent an important step toward fully-integrable, micron-scale bidirectional communication.

physics.optics↗

arXiv2022

Emergent Microrobotic Oscillators via Asymmetry-Induced Order

Spontaneous low-frequency oscillations on the order of several hertz are the drivers of many crucial processes in nature. From bacterial swimming to mammal gaits, the conversion of static energy inputs into slowly oscillating electrical and mechanical power is key to the autonomy of organisms across scales. However, the fabrication of slow artificial oscillators at micrometre scales remains a major roadblock towards the development of fully-autonomous microrobots. Here, we report the emergence of a low-frequency relaxation oscillator from a simple collective of active microparticles interacting at the air-liquid interface of a peroxide drop. Their collective oscillations form chemomechanical and electrochemical limit cycles that enable the transduction of ambient chemical energy into periodic mechanical motion and on-board electrical currents. Surprisingly, the collective can oscillate robustly even as more particles are introduced, but only when we add a single particle with modified reactivity to intentionally break the system's permutation symmetry. We explain such emergent order through a novel thermodynamic mechanism for asymmetry-induced order. The energy harvested from the stabilized system oscillations enables the use of on-board electronic components, which we demonstrate by cyclically and synchronously driving microrobotic arms. This work highlights a new strategy for achieving low-frequency oscillations at the microscale that are otherwise difficult to observe outside of natural systems, paving the way for future microrobotic autonomy.

nlin.AO↗