RESUMEN
Electrowetting-on-dielectric (EWOD) promises to be an important lab-on-a-chip approach for effectively manipulating droplets with electric field-controlled surface tension. Droplets manipulated in electrowetting-based devices are typically sandwiched between two parallel plates and actuated by digital electrodes. The size of pixilated electrodes limits the minimum droplet size that can be manipulated. Here, we report on a single-sided continuous optoelectrowetting (SCOEW) mechanism that enables light-patterned electrowetting modulation for continuous droplet manipulation on an open, featureless, and photoconductive surface. SCOEW overcomes the size limitation of physical pixilated electrodes by utilizing dynamic and reconfigurable optical patterns and enables the continuous transport, splitting, merging, and mixing of droplets with volumes ranging from 50 microL to 250 pL, over 5-orders of magnitude. This single-sided open configuration provides a flexible interface for integration with other microfluidic components, such as sample reservoirs through simple tubing. Light-triggered, parallel, and volume-tunable droplet injection with volume variation less than 1% has been demonstrated with SCOEW. The unique lateral field-driven optoelectrowetting mechanism also enables extremely low light intensity actuation, and droplet manipulation can be achieved by directly positioning the SCOEW chip on a LCD screen used in a laptop or portable cellular phone.
Asunto(s)
Técnicas Analíticas Microfluídicas/instrumentación , Micromanipulación/instrumentación , Dispositivos Ópticos , Soluciones/química , Soluciones/aislamiento & purificación , Diseño de Equipo , Análisis de Falla de Equipo , LuzRESUMEN
We report on a light-actuated, droplet based microfluidic platform enabling two-dimensional (2D) droplet manipulation on an open chamber with a single-side, featureless photoconductive surface. The droplet actuation mechanism is based on recently demonstrated floating electrode optoelectronic tweezers (FEOET), which enable light-induced dielectrophoretic forces to manipulate aqueous droplets immersed in electrically nonconductive oil, with a light intensity as low as 400 microW/cm2. In this paper, we study the shape effect of optical patterns for 2D droplet actuation, and demonstrate light-actuated droplet manipulation functions including 2D droplet transport, merging, mixing, and multidroplet processing, for up to 16 droplets in parallel. Such an open chamber platform also permits easy interfacing and integration with other microfluidic structures, such as wells and close-channel based droplet devices to increase its versatility for biochemical analyses.
Asunto(s)
Electroforesis por Microchip/instrumentación , Electroforesis por Microchip/métodos , Luz , Microfluídica , Microfluídica/instrumentación , Microfluídica/métodosRESUMEN
We report the integration of two technologies: droplet microfluidics using electrowetting-on-dielectric (EWOD) and individual particle manipulation using optoelectronic tweezers (OET)-in one microfluidic device. The integrated device successfully demonstrates a sequence involving both EWOD and OET operations. We encountered various challenges during integration of the two different technologies and present how they are addressed. To show the applicability of the device in cellular biology, live HeLa cells are used in the experiments. The unique advantages of EWOD and OET make their integration a significant step towards a powerful tool for many applications, such as single cell studies involving multiplexed environmental stimuli.
Asunto(s)
Separación Celular/instrumentación , Electricidad , Técnicas Analíticas Microfluídicas/instrumentación , Integración de Sistemas , Aire , Automatización , Impedancia Eléctrica , Diseño de Equipo , Células HeLa , Humanos , Magnetismo , Pinzas Ópticas , Propiedades de Superficie , Tensoactivos/químicaRESUMEN
We report an optical actuation mechanism, floating electrode optoelectronic tweezers (FEOET). FEOET enables light-driven transport of aqueous droplets immersed in electrically insulating oil on a featureless photoconductive glass layer with direct optical images. We demonstrate that a 681 mum de-ionized water droplet immersed in corn oil medium is actuated by a 3.21 muW laser beam with an average intensity as low as 4.08 muWmm(2) at a maximum speed of 85.1 mums on a FEOET device. FEOET provides a promising platform for massively parallel droplet manipulation with optical images on low cost, silicon-coated glass. The FEOET device structure, fabrication, working principle, numerical simulations, and operational results are presented in this letter.