Tetheredpyro-electrohydrodynamicspinningforpatterningwell-orderedstructuresat micro- andnano-scale

A lthough electrospinning (ES) allows the production of unsurpassed nanoscale polymer fibers, the major draw-backs are the nozzle-clogging and single-jet spinneret, respectively. This is a real limitation in terms of usable polymers and for patterning active organics. Nowadays the micro-engineering of smart materials could represent a new route for many fields of technology ranging from the production of electronic and photonic devices 1-3 to regener-ative medicine and tissue engineering. 4-7 An enormous technological interest is related to the possibility of patterning fibers directly in well-ordered patterns avoiding the deposition of nonwoven submicrometer mats often occurring in ES. 8,9 In the past decade several attempts have been made using field-induced 10-13 and near-field ES, 14,15 but only very recently, with the introduction of mechano ES, 16 has the production of well-ordered fiber patterns been achieved. Nevertheless, some drawbacks related to the complexity of the setup, the operating temperature, and the selection of usable materials for problems related to nozzle clogging still persist. Moreover, high temperature can cause deterioration of the optical and electronic properties of active organic materials eventually embedded in the functionalized fibers. On the other side, interfering effects due to closeness of multiple electrified nozzles ban working with multiple spinnerets. Here we introduce a revolutionary nozzle-free approach, the tethered pyro-electrodynamic spinning (TPES) operating in wireless modality, i.e., without electric circuit, electrodes, and voltage supply. This novel approach definitively simplifies the ES apparatus extending the nanofiber spinning also to active organic polymers preserving at the same time all the properties of conventional systems. Fiber drawing from the liquid polymer is driven through the pyroelectric charge generated into a ferroelectric crystal (i.e., LiNbO 3) able to induce the electro-hydrodynamics (EHD) pressure required for polymer manip-ulation without wires. The approach is highly flexible, simple, compact, and cost-effective when compared with classical ES, and last but not least, it allows working safely, avoiding the use of high-voltage equipment at kVolts scale. For the first time, in situ observation of fiber drawing is provided allowing real-time adjustments and full control of the process. Moreover the TPES adds to the capabilities of conventional ES the chance of printing polymer fibers even in the case of multiple drops opening the way to the multijetting spinneret modality for multiplexing and speeding up the fabrication process. Printing of micro-and nanofibers directly from a polymer drop with unprecedented order, direct writing of sharp/straight edges, and easy multijets electrospinning are demonstrated and reported. Experimental fabrication of patterns embedded with active molecules ensures that functionalized patterns preserve their functionalities after the TPES process. Results regarding the use of smart patterns for keeping alive and viable cultured cells are discussed. This study opens the way to innovative optogenesys analysis, guiding light for generating or trans-porting optical/electronic signals from and to cells. 17-21 The setup proposed in this work, unlike the conventional ES, is electrode-free and nozzle-free, Figure 1a,b. The method allows polymer nanofibers to be printed directly from a polymer drop overpassing the viscosity border of nozzle clogging in conventional inkjet systems. 22 The drop reservoir is placed directly on a flat substrate (base) while an electric field, Tethered Pyro-Electrohydrodynamic Spinning for Patterning Well-Ordered Structures at Micro- and Nanoscale (PDF Download Available). Available from: http://www.research