Reusable ionogel-based photo-actuators in a lab-on-a-disc

Abstract

This paper describes the design, fabrication and performance of a reusable ionogel-based photoactuator, in-situ photopolymerised into a lab-on-a-disc microfluidic device, for flow control. The the ionogel provides an effective barrier to liquids during storage of reagents and spinning of the disc. A simple LED (white light) triggers actuation of the ionogel for selective and precise channel opening at a desired location and time. The mechanism of actuation is reversible, and regeneration of the actuator is possible with an acid chloride solution. In order to achieve regeneration, the Lab-on-a-Disc device was designed with a microchannel connected perpendicularly to the bottom of the ionogel actuator (regeneration channel). This configuration allows the acid solution to reach the actuator, independently from the main channel, which initiates ionogel swelling and main channel closure, and thereby enables reusability of the whole device.

Light‐Driven Actuation in Synthetic Polymers: A Review from Fundamental Concepts to Applications

“…[ 220 ] The valves are actuated by simply applying localized white light irradiation (1 mW cm −2 ) with the ionogels reducing in volume due to merocyanine–spiropyran switching, and associated loss of water from the polymer. [ 221 ] By using different ionic liquid components within the gels, it is possible to tune the valve actuation time, facilitating sequential actuation events.…”

Light‐Responsive Shape‐Changing Polymers

“…Another conceptual solution was explored by the group of Diamond. In their approach, the spiropyran‐PNIPAm copolymers were prepared in ionic liquids . The relatively large solvent anions could effectively bind to the merocyanine, providing additional stabilization of the protonated form and shifting the SP↔MC equilibrium to the right .…”

Smartphone-Enabled Personalized Diagnostics: Current Status and Future Prospects

“…For instance, photoactuated valves and regions of light-modulated surface tension have been integrated before using lab-on-achip technologies and can respond to light from a screen as well [52]. Although these photoactive materials are mainly responsive to UV light [53,54], similar materials that react in the visible range may be developed in the future, enabling the integration of comparable photoactuated valves and pumps [53,55], including channels where the flow is controlled by surface tension gradients on the channel walls. Light actuation may also be used to enhance detection through photoelectrochemical methods.…”