Biomaterials out of thin air: in situ, on-demand printing of advanced biocomposites

The mission benefit analyses as described in our Phase I proposal (Objective #2, Section 6) are complete and contained in this report. As was appropriate for the information we had prior to the completion of the proof of concept, we focused on the benefits due to material subsitution and in situ resource utilization. These calculations alone show that our technology can save hundreds of kilograms of upmass for a potential human habit construction mission (a net mass savings of approximately one third per habitat module without ISRU, or mass savings including the full 240 kg per module if all materials are derived from ISRU). We have shown that continued advancement of this technology concept for use in a space mission environment is justified. We completed the proof of concept described in our Phase I proposal (Objective #1, Section 7), a twomaterial array of non-structural proteins. We created an implementation of each step in our technology concept (Figure 7.1) and demonstrated its critical functionality (Table 7.2). Our current host cells are S. cerevisiae, a yeast, genetically engineered to secrete our target materials, fluorescent-tagged proteins, when exposed to galactose. Our current print medium and substrate are a glucose-containing alginate medium deposited onto a calcium-and galactose-containing agar surface. The calcium gels the alginate, and the introduction of galactose when the cells contact the substrate triggers the material secretion. This way, the act of printing is combined with the act of creating a physical support for the cells and providing the material production stimulus, greatly simplifying the end-to-end-process. The biological chassis and printing hardware we created as part of this work can be re-used for future work by inserting a material coding region upstream of the fluorescent tag. Overall, we showed that our technology concept is sound. Our survey of future development pathways (Objective #3, Section 8) proved extremely informative in light of the lessons learned from our proof of concept work and mission scenario analyses. For example, we were able for the first time to distinguish between the levels of functionality provided by production of structural proteins, other polymers such as polysaccharides, and true organic-inorganic composites such as bone and mineralized shell. We were also able to survey the state of knowledge of the precise mechanisms involved in the formation of both non-protein-based structural materials, such as chitin and cellulose, and the inorganic phase of biominerals, and quantify our previously qualitative estimates of our technology concept's reliance on advances in other fields. Both of these analyses represent significant advances in formulating specific applications for our technology concept. For Objective #4 (Section 9 ), we surveyed potential collaborations with other projects and synergies with enabling technologies that are developing, including labs at Stanford University and Drexel University, Organovo, and Autodesk. Collaboration with tissue engineers at Organovo would allow our technology to develop in parallel with tissue printing technology, and collaboration with Autodesk would speed the development of software to translate standard 3D model file formats into commands usable by the bioprinter. Finally, we have been in touch with the team behind the 2013 NIAC Phase II 'Super Ball Bot -Structures for Planetary Landing and Exploration' and are planning to develop our biomaterial printing technology with the goal of enabling tensegrity-based rovers such as theirs to use lighter, more robust materials. A smooth transition from TRL 2 to TRL 3 assumes that the implementations of the technology concept which demonstrate critical functionality are also pathways for future development; while this is the case for most hardware or software projects, the multidisciplinary nature of our project, particularly the biological aspect of it, means that this is not always true. The most clear example of this in our Phase I work is the fact that our polyhistidine tag material binding method worked sufficiently well for a proof of concept demonstration, but is too cytotoxic for use in future work where we would need a much greater amount of the substrate to bind structural materials. Another, less obvious, example, is the case of genetic parts for material production. We have determined as part of this work that although there are large number of known genetic parts that correspond to non-structural materials, such as the proteins we used in this work, sequences for structural organic proteins, let alone biomineralization pathways, are still far from standardization (Table 6.6). These realizations allowed us to further subdivide our concept into more detailed development areas, some of which are clearly established at 1RL 3, others of which were newly identified sub-technologies moved from 1RL 1 to 1RL 2. Similarly, although a single feasibility /benefit analysis is sufficient for advancement from TRL 2 to TRL 3, not all potential benefits to a technology concept as broad in scope as ours are apparent at 1RL 2. Both our future pathways survey and our proof of concept work highlighted that the true mass savings potential of our technology concept cannot be quantified without modification of existing materials modelling tools to take into account the possibility of positional materials properties customization. Therefore, in our Phase I work, we have simultaneously both advanced one potential set of applications of our technology concept from 1RL 2 to TRL 3 and also identified a previously unknown set of applications and advanced it from 1RL 1 to 1RL 2. Our overall TRL advancement breakdown in shown in Table 3.2. Overall, we have moved the original formulation of our concept forward from TRL 2 to 1RL 3, and the expanded formulation of it presented in this document has been advanced from a combination of 1RL 1 and early 1RL 2 to an overall late TRL 2, using the definitions in Table 3.1. We have also identified the key areas necessary for both short-term and long-term advancement, and made recommendations for specific future work in the most promising directions. With future work on a 1-2 year timeframe to continue advancement to overall1RL 3, we will be well positioned to begin work on a specific space mission technology insertion path. Isaac Asimov Award from the Humanist Society, Horace Mann Award, Brown University, Team won blue ribbons at the NY Maker Faire. Significant media attention