Numerical simulations and experimental verifications of self-confined printing of droplets on microgroove surfaces. (A) Schematic representation of the local hydrophilic and hydrophobic treatment; (B), (C) numerical simulation and experimental phenomenon when the droplet diameter exceeds the groove width; (D), (E) numerical simulation and experimental phenomenon when the droplet deposition position deviates from the groove. The yellow dotted line in the figure represents the groove edge line.