Abstract: A method for forming microapertures in a thin sheet material where the area of each of the formed apertures generally ranges from about 10 square micrometers to 100,000 square micrometers. The method includes the steps of (1) placing the sheet material on a pattern anvil having a pattern of raised areas wherein the height of the raised areas is greater than the thickness of the sheet material; (2) conveying the sheet material, while placed on the pattern anvil, through an area where a fluid is applied to the sheet material; and (3) subjecting the sheet material to a sufficient amount of ultrasonic vibrations in the area where the fluid is applied to the sheet material to microaperture the sheet material in a pattern generally the same as the pattern of raised areas on the pattern anvil.