Manufacture of miniature bioparticle electromanipulators by excimer laser ablation

Multilevel microelectrode structures have been produced using excimer laser ablation techniques to obtain devices for the electro-manipulation of bioparticles using travelling electric field dielectrophoresis effects. The system used to make these devices operates with a krypton fluoride excimer laser at a wavelength of 248nm and with a repetition rate of 100Hz. The laser illuminates a chrome-on-quartz mask which contains the patterns for the particular electrode structure being made. The mask is imaged by a high-resolution lens onto the sample. Large areas of the mask pattern are transferred to the sample by using synchronized scanning of the mask and workpiece with sub-micron precision. Electrode structures with typical sizes of similar to 10 mu m are produced and a multi-level device is built up by ablation of electrode patterns and layered insulators. To produce a travelling electric field suitable for the manipulation of bioparticles, a linear array of 10 mu m by 200 mu m microelectrodes, placed at 20 mu m intervals, is used. The electric field is created by energising each electrode with a sinusoidal voltage 90 degrees out of phase with that applied to the adjacent electrode. On exposure to the travelling electric field, bioparticles become electrically polarized and experience a linear force and so move along the length of the linear electrode array. The speed and direction of the particles is controlled by the magnitude and frequency of the energising signals. Such electromanipulation devices have potential uses in a wide range of biotechnological diagnostic and processing applications. Details of the overall laser projection system are presented together with data on the devices which have been manufactured so far.