In this work, we demonstrate continuous and discrete functions in a digital microfluidic platform in a programmed manner. Digital microfluidics is gaining popularity in biological and biomedical applications due to its ability to manipulate discrete droplet volumes (nL–pL), which significantly reduces the need for a costly and precious biological and physiological sample volume and, thus, diagnostic time. Despite the importance of discrete droplet volume handling, the ability of continuous microfluidics to process larger sample volumes at a higher throughput cannot be easily reproduced by merely using droplets. To bridge this gap, in this work, parallel channels are formed and programmed to split into multiple droplets, while droplets are programmed to be split from one channel, transferred and merged into another channel. This programmable handling of channels and droplets combines the continuous and digital paradigms of microfluidics, showing the potential for a wider range of microfluidic functions to enable applications ranging from clinical diagnostics in resource-limited environments, to rapid system prototyping, to high throughput pharmaceutical applications.

The calculation of the molecular flux of sputtered indium gallium zinc oxide (IGZO) and oxygen during IGZO growth is used to generalize the optimum synthesis conditions for thin film transistors (TFTs). TFTs fabricated with an <mml:math display="inline"><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>O2 and IGZO incorporation <mml:math display="inline"><mml:mrow><mml:mtext>ratio</mml:mtext><mml:mo>≈</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:math>ratio≈1 demonstrated the best transfer curve with the resistivity of <mml:math display="inline"><mml:mrow><mml:mo>∼</mml:mo><mml:mn>5</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msup><mml:mspace width="0.3em"></mml:mspace><mml:mi>Ω</mml:mi><mml:mspace width="0.3em"></mml:mspace><mml:mi>cm</mml:mi></mml:mrow></mml:math>∼5×103Ωcm at <mml:math display="inline"><mml:mrow><mml:mo>∼</mml:mo><mml:mn>1</mml:mn><mml:mspace width="0.3em"></mml:mspace><mml:mi>mTorr</mml:mi></mml:mrow></mml:math>∼1mTorr of oxygen partial pressure. We demonstrate that the resistivity can be systematically varied almost 7 orders of magnitude by varying the oxygen partial pressure during sputtering. The relative Fermi level position was estimated as a function of the <mml:math display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>∕</mml:mo><mml:mi>IGZO</mml:mi></mml:mrow></mml:math>O2∕IGZO incorporation ratio. It is demonstrated that the resistivity curve with <mml:math display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub><mml:mo>∕</mml:mo><mml:mi>IGZO</mml:mi></mml:mrow></mml:math>O2∕IGZO incorporation ratio can be used as a powerful tool to determine the IGZO sputtering conditions for optimum TFT fabrication. Furthermore, the proposed oxygen incorporation calculation method is applied to subsequent passivation layer sputtering; when the oxygen incorporation rate during <mml:math display="inline"><mml:mrow><mml:mi mathvariant="normal">Si</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>SiO2 passivation sputtering is increased to a point that is higher than the amorphous IGZO incorporation rate during IGZO sputtering, the leakage current via the back channel is noticeably reduced.