A Reconfigurable Microfluidic Platform in Ice

Abstract

Microfluidic devices are popular tools in the biotechnology industry where they provide smaller reagent requirements, high speed of analysis and the possibility for automation. The aim of the project is to make a flexible biocompatible microfluidic platform adapted to different specific applications, mainly analytical and separations which parameters and configuration can be changed multiple times by changing corresponding computer programme. The current project has been supported by Vice Chancellor Trans-Campus Iinitiative. Channels and various design geometries can easily and rapidly be marked on ice with a CO 2 laser. Within seconds a microchannel pattern of features as small as 100 µm were obtained. The channels and design cavity dimensions are governed by the ratio of laser power by the beam velocity. The channels created in ice stay open for a duration which depend on their geometry and therefore on the ratio of the laser beam power by the beam velocity. Microchannels were created with a power/velocity ratio between 0.4 and 20 W/m. In this range of settings, the channels were 300 µm wide and stayed open for 2 s. After that they refreeze and the micropattern disappears in the ice bulk. Transport inside the channel can be obtained by the laser marking process alone. It is caused by the sheer surface tension within the melted area because of the temperature gradient within. The transport observed inside the channels was of the order of 1 mm/s in the laser experimental conditions (1.25 W and 100 mm/s). The temperature increase in the channel depends on the ratio of the laser power over velocity. High temperatures above 50°C can be achieved inside ice cavities. The. Table of Contents. ABSTRACT .

Optoelectronic reconfigurable microchannels

“…By scanning infrared lasers on ice, microchannels could be fabricated and reconfigured. 16,17 Furthermore, pumping has been demonstrated by sweeping a laser spot on a thin ice sheet. 18 In this scheme, density changes due to phase transition create microflows directed towards the melted zone as the spot moves.…”