Polymer-MEMS-Based Optoelectronic Display

In this paper, a novel all-polymer integrated microsystem, which realizes a 2-D display by integrating a 1-D array of polymer light-emitting diodes (PLEDs) with a polymer scanner of microelectromechanical system (MEMS), is presented. Electronic modulation of PLEDs forms the first dimension of the display (fast scan), and the scanner actuation orthogonal to the direction of PLED lineup forms the second one (slow scan). MEMS scanner (actuator) is fabricated on a polymer composite (FR4 material) with a double-sided process using lithography to pattern copper lines and laser micromachining to cut the scanner outline. PLEDs are fabricated on polyethylene terephthalate sheets. They have a thin-film structure of indium tin oxide, poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate), poly [2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene], and aluminum. The scanner is actuated electromagnetically in its slow-scan resonance mode at 49 Hz, generating a maximum displacement of 3.5 mm at a drive power of 84 mW with the help of a mini permanent magnet attached to the tip of the scanner and an off-chip energizing coil. Turn-on voltage of a PLED is 7.5 V, and each one generate a luminance of 0.3 cd/m
²
at 13 V, consuming 1.1-mA current. Successful operation of the integrated-display system is shown by forming a checker box image with a resolution of 20 × 7 and a size of 9 mm by 3.4 mm.