Micro Piezo is a term used for non-thermal (bubble jet) print head technology that uses dozens of high-precision mechanical pumps to produce variable-sized ink droplets on a page...

Unlike thermal print heads (fires the ink droplets by heat)Micro Piezo based heads are firing ink droplets by electricity (piezoelectric print heads)

Now you should understand also why e.g. our pigment inks the "FabricFast Ultra" or any other pigment inks containing binders only can work on printers with piezoelectric based print heads.
Pigment inks contain binders needed to be cured by heat and in case of a thermal print head curing is done before inks are getting to the fabric or paper what would immediately clog the print head.