Inkjet printed structures for smart lab-on-chip systems

Inkjet printing is a digital printing technique that is capable of depositing not only inks, but functional materials onto different substrates in an additive way. In this paper, applications of inkjet printed structures for microfluidic lab-on-chip systems are discussed. Such systems are promising for different chemical or biochemical analysis tasks carried out at the Point-of-Care level and therefore due to cost reasons are often fabricated from polymers. The paper discusses inkjetprinted wiring structures and electroactive polymer (EAP) actuators for use in microfluidic lab-on-chip systems. Silver and gold wirings are shown that are fabricated by printing metal nanoparticle inks onto polymer substrates. After printing the structures are sintered using argon plasma sintering, a low-temperature sintering process that is compatible with polymer substrates. The wirings consist of several electrode like structures and contact pads and feature minimum structure sizes of approximately 70 μm. They can be used for electrodes, fluid presence detectors and localized ohmic heaters in lab-on-chip systems. Based on that an all inkjet-printed EAP actuator then is discussed. Membrane-type bending actuators generate deflections of approximately 5 μm when being driven at a resonance frequency of 1.8 kHz with 110 V. Derived from that and assuming passive valves on-chip pumping rates in the range of 0.5 ml/min can be estimated.