Micro-fluidic devices for control of single cells

As we spend much time looking at the properties of yeast cells, we are interested in isolating single cells and subjecting them to a controlled environment for prolonged periods of time.  We turned to micro-fluidics for just these purposes.  Strictly speaking, micro-fluidics are systems of micron sized channels fabricated through various techniques, through which liquids may be flown for any desired purpose.  We found during our investigations that SU-8, a negative photo-resist commonly used in the fabrication of micro-fluidic devices, emits light when excited with light (in a two-photon microscope) and polymerizes.  In order to make micro-fluidic devices, we spin coat microscope slides with the resist, and photo-cure the resist using translation stages and highly focused laser light emitted by our groups Ti:Sapphire LASER. During the process we found a method of predicting the channel width from the intensity of emitted light during the exposure process.  The final steps involved pouring and curing PDMS to create the micro-fluidic devices from our fabricated “master” molds.  We have succeeded in creating the desired micro-fluidic channels and flowing and isolating cells within them for further observation with the same two photon microscope, or using microelectrodes. 

Our work on this matter is described in an article accepted for publication by the journal Lab On a Chip: M. Stoneman, M. Fox, C. Zeng, and V. Raicu, “Real-time monitoring of two-photon photo-polymerization for use in fabrication of micro-fluidic devices"