Fabrication and testing of the smallest "flute" on syringe needles

Nowadays, lasers, as innovation tools, provide extraordinary opportunities in a wide range of material processing and manufacturing applications. Here, we present using an ultra-short laser to fabricate a flute in a university's lab on a syringe needle. By finely controlling the laser power and drilling time, holes can be drilled at one side but not penetrate the whole needle. With a set of holes arranged in a straight line, the needle acts as a "flute" when the gas flows into it. A microphone measures its acoustic frequency. Different tones were observed by changing the resonance length of the needle. Our work demonstrates the fabrication and testing of miniature flute on a syringe needle.