Continuous novelty as the basis for creative advance in rapidly developing different form-factor microelectronic devices requires seamless integrability of batteries. Thus, in the past decade, along with developments in battery materials, the focus has been shifting more and more towards innovative fabrication processes, unconventional configurations, and designs with multi-functional components.We present here, for the first time, a novel concept and feasibility study of a 3D-microbattery printed by fused-filament fabrication (FFF). The reversible electrochemical cycling of 3D printed lithium iron phosphate (LFP) and lithium titanate (LTO) composite polymer electrodes vs. the lithium metal anode has been demonstrated in cells containing conventional non-aqueous and ionic-liquid electrolytes. We believe that by using comprehensively structured interlaced electrode networks it would be possible not only to fabricate free form-factor batteries but also to alleviate the continuous volume changes occurring during charge and discharge.

The high areal-energy and power requirements of advanced microelectronic devices favor the choice of a lithium-ion system, since it provides the highest energy density of available battery technologies suitable for a variety of applications. Several attempts have been made to produce primary and secondary thin-film batteries utilizing printing techniques. These technologies are still at an early stage, and most currently-printed batteries exploit printed electrodes sandwiching self-standing commercial polymer membranes, produced by conventional extrusion or papermaking techniques, followed by soaking in non-aqueous liquid electrolytes. In this work, we suggest a novel flexible-battery design and report the initial results of development and characterization of novel 3D printed allsolid-state electrolytes prepared by fused-filament fabrication (FFF). The electrolytes are composed of LiTFSI, polyethylene oxide (PEO), which is a known lithium-ion conductor, and polylactic acid (PLA) for enhanced mechanical properties and high-temperature durability. The 3D printed electrolytes were characterized by means of ESEM imaging, mass spectroscopy, differential scanning calorimetry (DSC) and electrochemical impedance spectroscopy (EIS). TOFSIMS analysis reveals formation of lithium complexes with both polymers. The flexible all-solid LiTFSI-based electrolyte exhibited bulk ionic conductivity of 3 × 10 −5 S/cm at 90°C and 156ohmxcm 2 resistance of the solid electrolyte interphase (SEI). We believe that the coordination mechanism of the lithium cation by the oxygen of the PLA chain is similar to that of PEO and local relaxation motions of PLA chain segments could promote Li-ion hopping between oxygens of adjacent CH-O groups. What is meant by this is that PLA not only improves the mechanical properties of PEO, but also serves as a Li-ion-conducting medium. These results pave the way for a fully printed solid battery, which enables free-form-factor flexible geometries.

SummaryA microbial fuel cell (MFC) was operated with a pure culture of Cupriavidus basilensis bacterial cells growing in the anode compartment in a defined medium containing acetate or phenol. Operating this mediator-less MFC under a constant external resistor of 1 kΩ with acetate or phenol led to current generation of 902 and 310 mA m−2 respectively. In the MFC which was operated using acetate or phenol, the current density measured from the plankton bacterial cells with a fresh electrode was 125 and 109 mA m−2, respectively, whereas the current obtained with biofilm-covered electrodes in sterile medium was 541 and 228 mA m−2 respectively. After 72 h in the MFC, 86% of the initial phenol concentration was removed, while only 64% was removed after the same time in the control MFC which was held at an open circuit potential (OCP). Furthermore, SEM and confocal microscopy analyses demonstrated a developed biofilm with a live C. basilensis population. In conclusion, in this study we demonstrated, for the first time, use of C. basilensis facultative aerobe bacterial cells in a MFC using acetate or phenol as the sole carbon source which led to electricity generation.

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Cyt1Aa is a d-endotoxin protein that is produced by Bacillus thuringiensis subsp. israelensis. It is a membrane pore-forming toxin that is lethal to insect larvae and is broadly cytolytic to vertebrate as well as invertebrate cells. Cyt1Aa is produced as a protoxin of 27 kDa. Proteolytic activation results in a reduction of the molecular mass to approximately 23-24 kDa and a threefold increase in activity. In this research, Cyt1Aa crystals were purified from B. thuringiensis IPS78/11 harbouring the expression vector pHT-cyAp20. The activity of the activated form of Cyt1Aa (23-24 kDa) was examined on a pathogenic strain of the Gram-negative Escherichia coli and the Gram-positive species Staphylococcus aureus. The Cyt1Aa minimal inhibitory concentration for E. coli and S. aureus was 1.25 and 5 mg ml "1 , respectively. Cyt1Aa was found to be bactericidal for E. coli, whereas it was bacteriostatic for S. aureus. Furthermore, Cyt1Aa increased the lethal effect when acting in combination with antibiotics. The association of Cyt1Aa with cells of these two bacteria was demonstrated by Western blot analysis using antibodies against the whole d-endotoxin crystal. Scanning electron microscopy displayed damage to Cyt1Aa-treated cells. Ion imbalance due to damage of the cell walls and membranes was confirmed by X-ray microanalysis. These experiments show that Cyt1Aa has an antibacterial effect on pathogenic species and demonstrate, apparently for the first time, that exogenous Cyt1Aa has a bactericidal effect upon Gram-negative bacteria.

A bio electrochemical cell (BEC) was constructed as a typical two-chamber microbial fuel cell (MFC), except that it was operated under external voltage instead of constant resistance as in an MFC. The anode chamber contained a pure culture of Pseudomonas putida F1 grown in a minimal medium containing toluene as the sole carbon and energy source. Operating the BEC under external voltages of 75, 125, 175, 250 and 500 mV (versus an Ag/AgCl reference electrode) led to increased bacterial cell growth to an OD 600 of 0.62-0.75, while the control BEC, which was not connected to external voltage, reached an OD 600 of only 0.3. Examination of the current generated under external voltages of 75, 125, 175, 250 and 500 mV showed that the maximal currents were 11, 23, 28, 54 and 94 mA m -2 , respectively. Cyclic voltammetry experiments demonstrated an anodic peak at 270 mV, which may imply oxidation of a vital molecule. The average residual toluene concentration after 147 h in the BEC operated under external voltage was 22 %, whereas in the control BEC it was 81 %. Proteome analysis of bacterial cells grown in the BEC (125 mV) revealed two groups of proteins, which are ascribed to charge transfer in the bacterial cells and from the cell to the electrode. In conclusion, operating the BEC at 75-500 mV enabled growth of a pure culture of P. putida F1 and toluene degradation even in an oxygenlimited environment.