Agile micro- and nano-fluidic control is critical to numerous life science and chemical science synthesis as well as kinetic and thermodynamic studies. Electrical addressability of lab-on-chip devices currently requires external switching devices for each individual electrode for droplet transport, merging, and splitting. Thus for complex arrays, many switching devices and interconnections are needed and scale directly with the number of elements (increased size or resolution). Therefore fabrication processes and cost can be complicated and expensive as the number of input-output connections becomes unwieldy. The active matrix (AM) addressing method integrated with an electrofluidic platform is a significant breakthrough for complex electrofluidic arrays (increased size or resolution) with enhanced function, agility and programmability because the AM method can minimize the number of control lines necessary (m + n lines for the m x n elements array) as is used in liquid crystal display technologies.

We have previously demonstrated arrayed amorphous indium gallium zinc oxide (a-IGZO) thin film transistors as a platform and the control of an electrofluidic array by AM addressing method. An a-IGZO semiconductor active layer is used because of its high mobility, low-temperature processing and transparency for spectroscopy and imaging. However, the a-IGZO transistors and an electrofluidic array were connected by external wires because the electrical properties of the a-IGZO thin film transistors were degraded after passivation. The degradation is likely due to reaction of hydrogen with a-IGZO active layer during PECVD SiO₂ passivation and post-annealing process, and this can be mitigated by changing deposition temperature and annealing ambient. In this study, the effects of hydrogen and oxygen on the PECVD passivated a-IGZO thin film transistors is investigated as a function of deposition temperature and post annealing ambient. The change of hydrogen and oxygen concentration in both the IGZO active layer and SiO₂ passivation layers are discussed. Finally, we review the process flow for fully integrated electrofluidic arrays on an a-IGZO transistor array and the programmable addressability of electrofluidic devices by AM addressing method. The requisite material and device parameters will be discussed for optimal active matrix addressing from device measurements in context with a VGA scale active matrix addressed electrofluidic platform.