A microfluidic labyrinth self-assembled by a chemical garden

Area of Science:

• Materials Science
• Chemical Engineering
• Microfluidics

Background:

• Chemical gardens are self-assembling precipitates formed from metal salts and precipitating anions.
• These structures have potential applications in creating controlled reactive materials.

Purpose of the Study:

• To investigate the formation of self-assembled microfluidic labyrinths in chemical garden systems.
• To explore the influence of silicate concentration and metal salt type on labyrinth morphology.
• To assess the potential for controlling labyrinth structure and orientation.

Main Methods:

• Utilized two chemical garden systems: copper(II) chloride (CuCl2) and copper(II) nitrate (Cu(NO3)2) seed crystals.
• Submerged seed crystals in sodium silicate solutions of varying concentrations (3-5 M).
• Observed labyrinth formation and precipitate growth modes within a vertical 2D Hele-Shaw reactor.

Main Results:

• Self-assembled microfluidic labyrinths were successfully produced in both CuCl2 and Cu(NO3)2 systems.
• Labyrinth formation was dependent on silicate concentration, with specific ranges for each copper salt.
• Structures featured silicate exteriors and hydrated metal salt mineral interiors.
• Bubble-guided tube orientation within labyrinths could be controlled by altering the 2D reaction cell angle.

Conclusions:

• Silicate concentration is a critical factor in directing chemical garden labyrinth formation.
• The angle of the reaction cell offers a method for controlling the orientation of self-organized microfluidic structures.
• These findings suggest potential for creating tailored microfluidic devices and advanced materials.