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. 2022 Jan 10;11:e00261. doi: 10.1016/j.ohx.2022.e00261

Fig. 9.

Fig. 9

Photograph of a) the assembled DOT PCB, b) the empty ‘casing (back)’, c) the ‘casing (front)’ with the ‘Touch plate’ wire visible and d) the completely assembled CO2 traffic light.