Microtube fabrication based on femtosecond Bessel beam and its flexible driving with external magnetic field

Microtube, with simple and uniform geometry, is one of the basic structures in micro/nano field. We present a method for the fabrication of magnetic drivable microtubes, by direct femtosecond laser writing combined with magnetron sputtering with metal layer. Femtosecond laser beam is modulated into Bessel beam with spatial light modulator (SLM), and then Bessel beam is focused with a high numerical aperture objective. Microtubes are fabricated by scanning focused femtosecond Bessel beam in a sample anchored on a three dimension stage. Followed by magnetron sputtering a nickel layer, the microtubes exhibit supermagnetic property and can be flexibly driven by external magnetic field. In this study, the propagation and high numerical aperture focusing properties of femtosecond Bessel beams are investigated. Microtubes, with well controlled diameter, length and distribution are efficiently fabricated. Rapid steering of nickel coated microtubes along specific route in fluid environment with external magnetic field has been realized. The steering of microtubes can be realized in various fluid environments. This method is flexible, controllable and efficient and the fabricated drivable microtubes have a promising applications in noninvasive surgery, targeted drug delivery, bioimaging or biosensing and microenvironment cleaning.