Principal Investigator at ASE: Prof. Pasi Kallio
Duration of the project: 2007 – 2009
Project description:
The project studied the use of optically induced electric fields in diagnosing diseases from a droplet of patient’s blood shortly at the testing site. The general objective is to decrease the sample volume needed as well as the size and the power consumption of the diagnosis device, such that the diagnosis can be made from a droplet of blood using a portable pocket-size device.
The method studied in this project facilitates the transport, division and mixing of the sample droplets (such as serum, plasma and whole blood) with reagents without external pumps. The liquid droplets are moved with an electric field which is generated using a light beam. Special, so called photo-conductive materials, are needed to change the electric conductivity with the light. By switching the light beam on and changing its place, the electric field experienced by the droplet can be changed altering the contact angle of the droplet and thus, finally moving the droplets assuming the materials and control parameters are correctly chosen.
This project focused on the studying the basic phenomena and technology of this optically induced digital microfluidics. In the project, a model describing the electrical properties of a system being composed of an optoelectric chip and a liquid droplet was created.
Furthermore, models describing the flow behaviour of a liquid drop in microfluidic channels were created. The models can be used for example for designing functional optoelectric microfluidic chips and cartridges.
In addition to the modelling aspects, methods and tools for experimental characterization were developed. The methods and tools include fast and high resolution measurement of an electric impedance of a device and characterization of liquid droplet flow using machine vision.
Thesis works:
• Antti-Juhana Mäki: “Optically Induced Electric Fields and Their Use in Microfluidics and Cell Manipulation Applications”, Master of Science Thesis, 2010
• Juha Hirvonen: “Estimation of Injection Volume in Capillary Microinjection Using Electrical Impedance Measurement”, Master of Science Thesis, 2010
Publications:
• Mäki, A-J., Ronkanen, P. & Kallio, P. "Modeling Continuous Optoelectrowetting Device". Submitted to Second European Conference on Microflduics, Toulouse, France, December 2010.
• Heiskanen, V., Marjanen, K. & Kallio, P. “Machine Vision based Measurement of Dynamic Contact Angles in Microchannel Flows”. Journal of Bionic Engineering, Elsevier. Volume 5, Number 4, 2008. Pp 282-290.
• Bhagavati, V., Heiskanen, V., & Kallio, P. ”An Experimental Investigation of Liquid Plug Flows in Polymeric Mini-channels”. Proceedings of the Seventh International ASME Conference on Nanochannels, Microchannels and Minichannels. Pohang, South Korea, June 2009.
• Hirvonen, J. Vilkko, M., Roinila, T. & Kallio, P. “Estimation of Electrical Cell-Capillary Admittance During Injection with Frequency Response Method”. Proceedings of the 17th IFAC World Congress (IFAC WC 2008). Seoul, Korea, July 2008.
Funding:
• The Academy of Finland
Partners:
• Professor Heikki Koivo and Professor Quan Zhou Department of Automation and Systems Technology, Helsinki University of Technology
Personnel:
• MSc Antti-Juhana Mäki
• MSc Valtteri Heiskanen
• MSc Juha Hirvonen
• BSc Venkataramana Bhagavati