On-chip particle-laden droplet dispensing by disposable inkjet system

We succeeded in dispensing micro-droplet by a disposable on-chip inkjet mechanism. Novelty of this paper is summarized as follows. (1) We employed a glass plate bonded Poly-dimethylsiloxane (PDMS) membrane to obtain leaf spring structure whose spring coefficient is 14 times of the conventional PDMS membrane. As a result, we succeeded in dispensing droplets continuously (up to 10 Hz) by vibrating the membrane using the multilayers piezoelectric actuator attached to the PDMS disposable chip. (2) The nozzle for droplet dispensing was fabricated by thick photoresist (SU-8) to obtain the hydrophobic surface which prevents any undesired satellite droplets produced. Consequently the accuracy of position of the droplet dispensing was achieved ± 5 μm. The size of the droplet produced from the disposable nozzle (diameter = 100 μm) was in the range of 95–105 μm at the applied voltage of 105 V.