Conductive suspension flows for soft electronics

Today, most electronics and robots are based on solid metals and semiconductors. This project aims at “Electrofluids” that conduct electrons while flowing as liquids.

Because liquids have virtually no yield strength, they are ideal materials to replace solid metal leads in truly soft devices. ELECTROFLUID uses highly concentrated suspensions that are liquid in a wide temperature range.

Transient conductive networks in suspended particles of commonly used conductors provide high level of electronic conductivity at the viscosities required for soft electronics and robots.

They contain common conductive materials such as carbon, silver, gold, and copper and do not require specialized low-melting alloys of gallium or other expensive elements.In order to create stable Electrofluids with large conductivity at low viscosity with tuneable rheology, I study the interplay between particle-particle friction, contact resistance, percolation, bulk resistance, and suspension viscosity.

I use both custom-synthesized and commercial particles in a size range of tens of nanometres to few microns and with different shapes, modify their surfaces with conventional and pi-conjugated surfactants, and formulate concentrated suspensions that exhibit large conductivity at low viscosity.

The combination of different particle sizes, shapes, and fluids enables tuning the properties of the fluid towards specific application cases, for example to create highly flexible leads for logic signals versus high-power connections for the connection of actuators.

The fluids will be encapsulated in elastomer tubes or micropatterned surfaces as they are commonly used in stretchable electronics.

The specific aims of the project are: (i) to design highly concentrated suspensions that form transient percolating networks, (ii) to use this knowledge and synthesize fluids with tuneable electrical conductivity at low viscosity, (iii) to demonstrate that Electrofluids can be curtailed for particular applications.