Bio-inspired Optofluidic Molecular Communication with Photothermally Actuated Microrobot Swarms

Molecular communication (MC) offers a bio-inspired paradigm for information transfer in environments inaccessible to conventional electromagnetic waves. However, translating MC concepts to the microscale has been hampered by a lack of integrated, biocompatible testbeds. Inspired by biological spectral-dependent photothermal transduction of specific light wavelengths into thermal energy, we present the first fully integrated microscopic MC platform utilizing photothermally responsive microrobot swarms. Our platform employs core-shell microrobots that exhibit a strong photothermal response, enabling precise and non-invasive navigation within microfluidic channels via near-infrared (NIR) light. This optofluidic architecture facilitates a symbiotic dual-bit encoding scheme, which concurrently modulates information onto both microrobot arrival and the optical control states. We demonstrate a complete communication workflow, from microrobot emission and laser-guided modulation to real-time optical detection and signal demodulation. The system achieves a data rate of 0.63 bits · min^-1 with a low bit error rate of 4%, validated by a multi-sampling detection algorithm and the transmission of the ASCII string "HELLO WORLD". This work provides a robust testbed for validating MC theories in biologically relevant microenvironments and serves as a step toward applications in the Internet of Bio-Nano Things.