Progress in printing and imaging with optical fibers

In the last 5 years, there has been rapid progress by many groups in endoscopic imaging with multimode fibers. Imaging modalities such as fluorescence, confocal, photoacoustic and two-photon with sub-micrometer resolution have... [ view full abstract ]

In the last 5 years, there has been rapid progress by many groups in endoscopic imaging with multimode fibers. Imaging modalities such as fluorescence, confocal, photoacoustic and two-photon with sub-micrometer resolution have been shown through several tens of centimeter long fibers of diameter less than a human hair. I will review this body of work and introduce a new use for this fiber technology, namely for advanced manufacturing that we coin endo-fabrication.
The concept is to do micro-fabrication by additive and subtractive means in areas that are difficult to reach with conventional optics.

In one demonstration, the fiber is used as a thin objective lens for the micro fabrication of arbitrary shapes 3D objects at the distal end of the fiber. The objects are manufactured by two photon polymerization by digitally scanning a temporally and spatially focused ultrafast pulse. A replica of the Chichen Itza pyramid with a base length of 60 um was manufactured through a 5 cm long, 560 um diameter fiber.

In another demonstration, a thin fiber capillary is filled with a liquid. Light is then used to eject micro droplets with a velocity suitable to print functional or biological materials. The laser-induced shockwaves overcome conventional problems in inkjet printing methods, such as aggregation and clogging issues when viscous material is printed. The range of printable liquids with our device was significantly extended compared to conventional inkjet printers performances. In addition, the laser-induced flow focusing phenomenon allowed to controllably generate viscous micro-droplets up to 210 mPa s with a diameter smaller than the nozzle from which they originated (200 µm). Inks containing proteins were printed without altering their functional properties thus demonstrating that this jetting technique is potentially suitable for bio-printing.

We expect to combine 3D structuring and precise biological material delivery in the structure as a mean to build functional biological structures.