Multiscale 3D-printing of Microfluidic AFM Cantilevers
Microfluidic atomic force microscopy (AFM) cantilever probes have all the functionality of a standard AFM cantilever along with fluid pipetting. They have a channel inside the cantilever and an aperture at the tip. Such probes are useful for precise fluid manipulation at the desired location, for example, near or inside cells. They are typically made by complex microfabrication process steps, resulting in expensive probes. Here, we used two different 3D additive manufacturing techniques, stereolithography and two-photon polymerization, to directly print ready-to-use microfluidic AFM cantilever probes. This approach has considerably reduced the fabrication time and increased the design freedom. One of the probes, 564μm long,30μm wide,30μm high, with a 25μm diameter channel and 2.5μm wall thickness had a spring constant of 3.7 N/m and the polymer fabrication material had an elastic modulus of 4.2 GPa. Using these 3D printed probes, AFM imaging of a surface, puncturing of a cell membrane, and aspiration at single cell level have been demonstrated.