Droplet volume adjustable microinjectors using a microheater array

We present the design, fabrication and experimental results of the thermofluidic digital microinjectors, whose ejected droplet volumes are adjusted by the digital operation of a microheater array composed of four microheaters. We measured a life history of the microbubbles generated on the microheater array. The ejected droplet volume is adjusted as 1.4/spl plusmn/0.5, 4.2/spl plusmn/1.0, 6.0/spl plusmn/1.3, 11.0/spl plusmn/1.9 p/depending on the number of active microheaters. Thus, volume adjustable capability of the digital microinjectors has the potential to enhance a image quality as well as printing speed.