A disposable syringe includes a tubular needle seat inserted into a barrel for fixing a needle cannula. The handle assembly includes a riser, an upper limb, and a lower limb, wherein the upper and lower limbs each include a distal end and a proximal end connected to the riser. When the array and the conventional power MOSFET array disposed under the source pad are connected to an array pair by using circuit connection region, the same gate pad and source pad can be shared, so as to achieve an objective of increasing device integration. The first paint type is a water-based, non-toxic acrylic paint and the applicator means atomizes the paint to apply a plurality of droplets to the exposed nail.