Robotic pendant drop: containerless liquid for μs-resolved, AI-executable XPCS

Abstract

The dynamics and structure of mixed phases in a complex fluid can significantly impact its material properties, such as viscoelasticity. Small-angle X-ray Photon Correlation Spectroscopy (SA-XPCS) can probe the spontaneous spatial fluctuations of the mixed phases under various in situ environments over wide spatiotemporal ranges (10−6–103 s /10−10–10−6 m). Tailored material design, however, requires searching through a massive number of sample compositions and experimental parameters, which is beyond the bandwidth of the current coherent X-ray beamline. Using 3.7-μs-resolved XPCS synchronized with the clock frequency at the Advanced Photon Source, we demonstrated the consistency between the Brownian dynamics of ~100 nm diameter colloidal silica nanoparticles measured from an enclosed pendant drop and a sealed capillary. The electronic pipette can also be mounted on a robotic arm to access different stock solutions and create complex fluids with highly-repeatable and precisely controlled composition profiles. This closed-loop, AI-executable protocol is applicable to light scattering techniques regardless of the light wavelength and optical coherence, and is a first step towards high-throughput, autonomous material discovery.

Towards a modular architecture for science factories

“…Robotic pendant drop provides an end-to-end automated, μs-resolved XPCS workflow for studying the dynamics and structures of complex fluids. Ozgulbas et al 65 recently demonstrated that Brownian dynamics of nanoparticle colloid in a pendant drop is consistent with the reference setup such as thin-walled quartz capillaries. Furthermore, the pendant drop setup can be integrated with a robotic arm (UR3e) to fully automate sample preparation, characterization, and disposal.…”