Plasma techniques are especially useful because they can deposit ultra thin (a few nm), adherent, conformal coatings.[23] Glow discharge plasma is created by filling a vacuum with a low-pressure gas (ex. argon, ammonia, or oxygen). The gas is then excited using microwaves or current which ionizes it. The ionized gas is then thrown onto a surface at a high velocity where the energy produced physically and chemically changes the surface.[24] After the changes occur, the ionized plasma gas is able to react with the surface to make it ready for protein adhesion.[25] However, the surfaces may lose mechanical strength or other inherent properties because of the high amounts of energy.