Evaporation driven smart patterning of microparticles on a rigid-soft composite substrate

Rameez Iqbal, Atsushi Matsumoto, Daniel Carlson, Kazumi Toda Peters, Riccardo Funari, Ashis K. Sen, Amy Q. Shen

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Hypothesis: A liquid droplet on a rigid polydimethylsiloxane (PDMS) substrate exhibits a higher receding contact angle (θr), therefore, recedes earlier than its softer counterpart. The three-phase contact line of a suspension droplet on a composite rigid-soft PDMS substrate can be selectively tuned wherein the contact line recedes on the rigid substrate sooner and approaches toward the softer side, with microparticles eventually being deposited in the softer substrate region. Experiments: A composite PDMS substrate containing soft cores of various shapes (circular and non-circular) surrounded by rigid matrices was fabricated by employing 3D printing and soft lithography. A sessile suspension droplet containing spherical microparticles was deposited on the composite substrate and evaporated under ambient conditions. The evaporation dynamics was recorded and analyzed. Findings: Evaporation-induced patterning (in circular, triangular, and rectangular areas) with sizes ranging from microns to millimetres were obtained. For the first time, by varying the ratio of the rigid-soft regions in the PDMS substrate, we were able to obtain different deposition sizes and shapes from an identical droplet. Instead of using lithographically patterned substrate, our simple methodology by using 3D printing and soft lithography opened up a new avenue for patterning microparticles based on a rigid-soft composite substrate.

Original languageEnglish (US)
Pages (from-to)927-937
Number of pages11
JournalJournal of Colloid And Interface Science
StatePublished - Oct 2022


  • Particle deposition patterns
  • Rigid-soft PDMS substrate
  • Sessile evaporating droplet
  • Three-phase contact line
  • Printing/methods
  • Physical Phenomena

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Biomaterials
  • Colloid and Surface Chemistry


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