Ultrafast laser microfabrication of a trapping device for colorectal cancer cells

Abstract

Although celltrapping devices have been microfabricated and widely used for manipulation of bio cells, devices that trap multiple cells simultaneously are difficult to design because fabrication is complicated and time consuming. We designed and manufactured a microfluidic device using a polycarbonate plate with a flatness less than 200μm and a gelatin-coated polyethylene terephthalate (PET) membrane. The device was used to capture colorectal cancer cells from one of the most common types of human malignant tumors. Microfluidic channels for the device were micromachined in minutes using a Computerized Numerically Controlled (CNC) engraving machine. We microfabricated multiple microholes on the PET membrane, which had a thickness of 13μm, using an ultrafast, 1025nm diode-pumped solid state femtosecond laser. The 100 microholes were drilled by spirally moving spot size of 4μm laser beam. It is very important to obtain smooth and clean surface to avoid cell damages when they are trapped on the device. The relationship between the diameter changes of the microholes and variations in laser output power as well as laser fluence were investigated through parametric analysis. The average diameter of the holes increased exponentially with laser power. The gelatin-coated PET membrane was attached to the polycarbonate device and a syringe with a tube controlled negative pressure inside the channels of the cell-trapping device. Maintaining negative pressure inside the channels under the microholes on the PET membrane, colorectal cancer cells were dropped using the cell dropping pipette and successfully captured for manipulation under same environmental condition.