Particle size distributions of OKI laser printer toner particles (a), magnetite particles (, b), and polymer (SAC) particles (c).
(a) Passive microchip for particle transfer experiments with as insulator material (dark gray) and M1, (conductors, pads); (b) floor plan of a multifunctional CMOS chip different with different matrices consisting of identical pixel electrodes; detail and side view of the matrices 1–3 investigated here with as insulator material (dark gray) and Al as conductor material (light gray).
Principle of selective particle desorption: a microchip with an array of pixel electrodes (a) is powdered with the microparticles (b). Subsequent air jet–induced desorption of particles from grounded electrodes [(c) electric fields are delineated by semielliptical clouds] results in a particle pattern that corresponds to the underlying electric field pattern (d). For the sake of clarity, the air flow was sketched in oblique angle.
Simulation of the electric field distribution above three neighboring electrodes (edge lengths and interspaces of ) switched on 0, 100, and . Note that the electric field is continuous. For better visualization discrete steps of gray scales are depicted with reference to the right column.
Checkerboard particle pattern on a passive chip after selective desorption of OKI laser printer toner particles with an air flow velocity (a) and after increase of the velocity to (b).
Checkerboard pattern on passive chips after selective desorption of magnetite particles (a) and SAC particles (b) with air flow velocities of 3 and , respectively.
A pattern of “ideal” dummy particles [(a) light gray] as mask for the selective deposition of “imperfect” particles (dark gray); after powdering the imperfect particles on the entire chip (b), previously uncoated electrodes are switched on voltage; an air flow induced lifts off dummy particles as well as of hereon deposited imperfect particles (c), which results in an inverted, contamination-free particle pattern (d). For the sake of clarity, the air flow was sketched in oblique angle.
SAC particle pattern after the selective desorption with magnetite dummy particles; previously masked electrodes (A1, A3, B2, C1, C3, D2) evince a significant decrease in contaminations compared with afore unmasked electrodes C2, D1, and D3.
Selective desorption of laser printer toner particles (OKI magenta) in a checkerboard pattern from the CMOS chip at an air flow velocity (a) and after increase of the velocity to (b). Matrices 1–3 feature different grid/electrode designs and surface coverages, respectively [see Fig. 2(b)]. The quality of the particle deposition pattern clearly depends on the electrode geometries.
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