Shear-induced unidirectional deposition of bacterial cellulose microfibrils using rising bubble stream cultivation

Grow with the flow – observing the formation of rheotactically patterned bacterial cellulose networks

“…This results in macroscopic net dipoles via the alignment from the fibers' reducing end to their non-reducing end. 38 We assume it is possible that the current flow driven alignment approach results in the same packing and that the hierarchical structure features persist even more distinct from the molecular to the macroscopic level by rheotactic structuring compared to other structuring approaches.…”

“…36,37 Using flow-producing rising bubbles, Chae et al also attained a unidirectional deposition of BCB. 38 Since structuring of BCB by flow has already yielded interesting results, it is worth considering the mechanism: if a biofilm grows in a flowing medium, its viscoelastic morphology responds to the mechanical stimulus of the flow. 39 The form thereby differs if the biofilm is fully surface attached or if it adheres at least at one point, while the rest of the biofilm moves with the flow as a so-called streamer.…”

“…36,37 Using flow-producing rising bubbles, Chae et al also attained a unidirectional deposition of BCB. 38…”

The intrinsic piezoelectric properties of materials – a review with a focus on biological materials

“…To increase ordering, methods such as mechanical stretching and electrical-eld polarisation have been trialled. 25,128,129 One particularly interesting approach was tested by Chae et al 130 They reported a method to induce remarkable parallel packing of bacterial cellulose microbrils during the bacterial culture by applying directional shear stress via rising bubbles. Cellulose based electroactive paper (EAPap) has received signicant attention, with a measured piezoelectric coefficient (d 31 ) as high as 1425 pm V À1 .…”

Electric Field-Induced Polarization Responses of Noncentrosymmetric Crystalline Biopolymers in Different Frequency Regimes – A Case Study on Unidirectionally Aligned β-Chitin Crystals

“…Many biopolymers have noncentrosymmetric crystalline structures with asymmetric arrangements of polymer chains. − When an external electric field is applied, their polarization responses can be manifested as electromechanically coupled strain, ,− electric polarization, − nonlinear optical process, − etc. For example, β-chitin and cellulose Iβ have crystalline structures with 2-fold helices along the chain axis (the c -axis of the unit cells), which are packed in parallel (i.e., pointing the same direction). − Due to the parallel packing and existence of a net dipole in the crystal unit cell, piezoelectricity has been anticipated for materials containing them. ,,− The noncentrosymmetric biocrystals are also active in nonlinear optical processes including second-harmonic generation (SHG) and sum-frequency generation (SFG) due to the lack of inversion symmetry. ,− Other electromechanical coupling responses under an electric field can also appear in both crystalline and noncrystalline domains, which include ion migration, electrostriction, electrostatic effect, and so on. , …”