Chemically Controlled Spatiotemporal Oscillations of Colloidal Assemblies

Alicia Altemose, María Antonieta Sánchez-Farrán, Wentao Duan, Steve Schulz, Ali Borhan, Vincent H. Crespi, Ayusman Sen

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


We report an autonomous oscillatory micromotor system in which active colloidal particles form clusters, the size of which changes periodically. The system consists of an aqueous suspension of silver orthophosphate microparticles under UV illumination, in the presence of varying concentrations of hydrogen peroxide. The colloid particles first attract each other to form clusters. After a short delay, these clusters abruptly disperse and oscillation begins, alternating between clustering and dispersion of particles. After a cluster oscillation initiates, the oscillatory wave propagates to nearby clusters and eventually all the clusters oscillate in phase-shifted synchrony. The oscillatory behavior is governed by an electrolytic self-diffusiophoretic mechanism which involves alternating electric fields generated by the competing reduction and oxidation of silver. The oscillation frequency is tuned by changing the concentration of hydrogen peroxide. The addition of inert silica particles to the system results in hierarchical sorting and packing of clusters. Densely packed Ag3PO4 particles form a non-oscillating core with an oscillating shell composed largely of silica microparticles.

Original languageEnglish (US)
Pages (from-to)7817-7821
Number of pages5
JournalAngewandte Chemie - International Edition
Issue number27
StatePublished - Jun 26 2017

All Science Journal Classification (ASJC) codes

  • Catalysis
  • General Chemistry


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