New, High-Performance Conductor Inks

The NASA solid-state ultracapacitor technology is based on the novel materials design and processes used to make the IBLC-type ultracapacitor. The IBLC concept is known to provide outstanding capacitance behavior but has been difficult to reproduce. NASA has developed a careful process to produce dielectric ink materials to be used in printed electronic applications with reproducibility. An individual cell is created by building electrodes on each side of the dielectric layer, and complete modules can be constructed by stacking multiple cells. Closely related NASA innovations on dielectric and conductive ink (electrode) formulations are key to the ultracapacitor construct, and are included in the technology package. Target performance criteria of this technology include the following: - Use of standard materials and processing methods - Robust solid-state device with no liquid electrolytes - High-energy densitytarget energy densities of 60 J/cc at a minimum operating voltage of 50 V - High dielectric breakdown strength (>250 V) - Excellent pulse-power performance; rapid discharge and charge - Reliable performance under repeated cycling (>500,000 cycles) Additional development work is underway to build and test complete capacitor modules and to further improve material properties and performance.

The NASA technology is based on a perovskite ceramic developed at MSFC, reduced lanthanum barium titanate (rLBT). rLBT is comprised of reduced barium titanate (BaTiO3) doped with lanthanum (La) and co-doped with potassium hydroxide (KOH). rLBT was developed while exploring the suitability of sintered perovskites to produce screen-printed ultracapacitors; the prototypes unexpectedly demonstrated an extreme sensitivity to moisture, prompting exploration of the material for use as a vapor-sensitive dielectric ink. To eliminate inconvenient high temperature firing necessary to produce capacitors, the inventors developed rLBT-loaded polymer composites capable of curing under low heat (110 degrees C) for epoxy or under ultraviolet (UV) light for UV-sensitive resin. At suitable ceramic particle loading concentrations, thin ink layers (30 micrometers) demonstrate RH sensitivity, instantaneously detecting breath vapor (RH change from 30% to 93%) with a recovery time of only 1s. Prototypes demonstrated near log-linear response curves over three orders of magnitude of capacitance with minimal drift (see Figures 1 and 2). NASA’s low temperature dielectric ink for humidity sensing is at technology readiness level (TRL) 4 (component performance has been validated in a lab setting) and the related patent is now available to license. Please note that NASA does not manufacture products itself for commercial sale.

NASA's technology is a dielectric materials formulation comprising polymers, organic binders, solvents, and surfactants, formulated together with a ceramic perovskite nanopowder. The ceramic nanopowder can be optimized for the required dielectric properties of capacitance, voltage breakdown, and leakage. This involves the addition of dopants or the use of advanced coatings on the powder particulates, and subsequent thermal treatments. The rheology of the formulation can be adjusted to work with a variety of coating or printing methods, from conventional thick-film methods to advanced inkjet or direct-write 3D printing methods used for printed electronics. 3D printing provides the ease of printed manufacturing along with the deposition of thinner layers (e.g., 5 microns in thickness vs. 50-100 micron layer via thick-film methods). Individual devices can then be formed in multilayer arrangements, or stacked and packaged as required for the given device application. The ultracapacitor described in MFS-TOPs-75 uses this dielectric material in its assembly. The ink composition is a careful blend of polyimide or polyvinylidene fluoride (PVDF) polymers, solvents, surfactants, and barium titanate nanopowders. Proper ratios are needed for viscosity and processability (e.g., nanopowder wetting and dispersion), along with the optimal ultracapacitor device performance.

NASAs solid-state ultracapacitor technology is based on the novel materials design and processes used to make the IBLC-type ultracapacitor. The IBLC concept is known to provide outstanding capacitance behavior but has been difficult to reproduce. NASA has developed a careful process to produce dielectric materials to be used in printed electronic applications with reproducibility. An individual cell is created by building electrodes on each side of the dielectric layer, and complete modules can be constructed by stacking multiple cells. Closely related NASA innovations on dielectric and conductive ink (electrode) formulations are key to the ultracapacitor construct, and are included in the technology package. Target performance criteria of this technology include the following: &#8226 Use of standard materials and processing methods &#8226 Robust, solid-state device with no liquid electrolytes &#8226 High-energy densitytarget energy densities of 60 J/cc at a minimum operating voltage of 50 V &#8226 High dielectric breakdown strength (> 25 MV/m) &#8226 Excellent pulse-power performance; rapid discharge and charge &#8226 Reliable performance under repeated cycling (> 500,000 cycles) Additional development work is underway to build and test complete capacitor modules and further improve material properties and performance.

Once genes for a desired material type, delivery mode, control method and affinity have been chosen, assembling the genetic components and creating the cell lines can be done with well-established synthetic biology techniques. A 3D microdeposition system is used to make a 3D array of these cells in a precise, microstructure pattern and shape. The engineered cells are suspended in a printable 'ink'. The 3D microdeposition system deposits minute droplets of the cells onto a substrates surface in a designed print pattern. Additional printer passes thicken the material. The cell array is fed nutrients and reagents to activate the engineered genes within the cells to create and deposit the desired molecules. These molecules form the designed new material. If desired, the cells may be removed by flushing. The end product is thus a 3D composite microstructure comprising the novel material. This innovation provides a fast, controlled production of natural, synthetic, and novel biomaterials with minimum resource overhead and reduced pre- and post-processing requirements.