Active control of finger sliding friction with different surface roughness in SDS solutions for underwater surface haptics

Underwater surface haptics based on friction modulation provide new concepts for immersive extended reality haptic technology. A previous study proposed a modulation method by using a voltage-controlled technique in saline solutions, demonstrating that finger friction was actively adjusted by external voltages. This work further investigated the voltage-controlled finger friction on 304 stainless steel plates with two surface roughness in sodium dodecyl sulfate (SDS) solutions with three concentrations. By changing the roughness, the effects of both increasing friction and reducing friction were observed. This can be attributed to the competitive mechanisms between the adsorption/desorption of the surfactant and the formation/dissolution of the metal oxide film. This study improves the understanding of the mechanisms of finger friction based on the voltage-controlled technique and verifies the feasibility of underwater friction modulation.