Hollis, NH-Industrial lasers have entered the world of cutting-edge biotechnology by way of a project designed to culture liver tissue. The cell-holding scaffolds of the Liver Chip are made of laser-machined polymers (polycarbonate, polyethylene terephthalate, and polyimide). For this project, which was developed by the Massachusetts Institute of Technology (MIT), extremely small channels and pores in the polymer scaffolds are micromachined using UV excimer lasers custom designed by J P Sercel Associates (JPSA, www.jpsalaser.com).
Jeffrey P. Sercel, JPSA president, explains, “Short-wavelength UV laser energy is ideal for clean-cutting, drilling, and shaping polymer and other materials that are difficult to micromachine using other technologies. Although an etching process can be used, such as reactive ion etching, UV laser technology allows processing of materials such as polycarbonate and polycyclo-olefins that offer favorable characteristics for biomedical applications.”
In the process, very fine and measured amounts of material are removed as a plasma plume by photo-ablation with each laser pulse, leaving a cleanly sculpted pore, channel, or feature.
The large size characteristic of the UV excimer laser beam enables it to be separated into multiple beamlets through near-field imaging techniques, so that multiple pores, for example, can be simultaneously bored with each laser pulse. Imaging techniques also allow sub-micron resolution so that nano-features can be effectively controlled and shaped. Manufacturing specifications require JPSA to micromachine scaffold thickness of 250 microns and channel depth of 200 microns, with pore depth of 50 microns.
An MIT team led by Linda Griffith, professor of mechanical engineering and biological engineering, and Karel Domansky, research scientist, developed the concept of the Liver Chip. It represents an example of systems biology as a model for human disease and as a tool in early drug discovery and development.