Demonstration of wetting of microgrooves. (a) Samples have been immersed in water for 30 s, only 5% of the gas remains, with about 95% of the gas fraction in the microgrooves substituted for water; (b) after 45 s, 4% of the gas remains; (c) after 60 s, 3% of the gas remains; (d) after 75 s, 2.5% of the gas remains; (e) after 90 s, 1.5% of the gas remains; (f) after 105 s, 1% of the gas remains; (g) after 120 s, about 0.5% of the gas remains; (h) after 135 s, only a little fraction of the gas remains; (i) after 150 s, almost all of the gas in the microgroove structures has been substituted for water.