**4.3. Millifluidic channels in 3D-printed chips for microplasmas**

3D-printing [109–122] was accomplished using a 3D-printer (~\$1000) to rapidly prototype 3D-chips in a few hours (or less), thus obviating the need for cleanrooms and lithography. We used 3D-printing to fabricate hybrid chips (fitted with a quartz plate and needle electrodes) for microplasma formation in millifluidic channels [146, 147, 149]. An example is shown in **Figure 12**.
