Bioprinter: Overview

We modified a 3D clay printer into a bioprinter compatible with our novel bioink. We created a biomaterial composition that can incorporate microbes to serve as a bioink for bioprinting 3D living building materials for Mars.

The Concept of In-Situ Resource Utilization

In-Situ Resource Utilization (ISRU) is the concept of using local materials found at a operating destination (such as the Moon, Mars, or an asteroid) to supplement the operation or engineering solution instead of bringing the necessary supplies to the site. This could include support for human or robotic exploration, instead of transporting everything from Earth. The goal is to reduce the mass, cost, and complexity of space missions by utilizing the local resources on Mars.

Why is it Important for a Space Mission

In space missions, every gram of weight matters, whether it’s essential mission supplies or a gorilla suit. Each gram of weight costs on average about $10 to send to low earth orbit and even more when sending the package further into space ([1]). This is because a large amount of rocket fuel is required to provide the force necessary to exceed Earth’s gravitational pull. The benefit of ISRU is reducing the mass required for successful operation thus reducing the costs of bringing our project to Mars.

ISRU is critical for developing extraterrestial colonization because it is a step towards using environmental resources. While the initial supplies can come from Earth, it will not be sustainable to continue relying on Earth’s resources. ISRU can also propel Earth’s research and future missions by bringing back samples or extracting fuel and other resources from the environment. This can lead to improved success in future missions and guiding the next few missions.

The Limitations of Current Platforms:

Based on industrial ISRU programs and past iGEM teams, there are a variety of issues and limitations that need to be addressed and we anticipate that we may run into some of these problems. It is important to establish an experimental solution or workaround during the design phase of our bioprinter.

Table 1: Limitations and their impacts

Limitations	Impact	Potential solutions
Low resolution due to low budget([2])	Limits geometries printable by printer	Perform post-processing steps or ignore issue due to lack of requirement for high resolutions (since we are printing brick-like structures)
Difficult to change designs due to closed system and non-universal components([2])	Limits usable components in printers, must use components and parts made for	Keep open systems with infrastructure made for repairs and quick access, develop universal connectors
Limited layer stacking([3]) (2D / 2.5D only)	Limits 3D structures on printability	Test bioink compatability in 3D structures or manually construct 3D structures after printing
Limited access to resources when doing ISRU ([4])	Difficult to produce bioink and acquire bioink resources on Mars	Use easily accessible resources like martian regolith and recycling water
Energy consumption ([5])	Energy resources are valuable, thus reducing energy consumption is highly favourable	Use as little energy during material processing, let bacteria do the work

Bioprinting as a More Suitable Alternative

With bioprinting, there are a lot of potential upsides in manufacturing biological material compared to traditional methods. Current solutions often utilise pre-exisiting framework to guide the biocementation process like repairing concrete cracks and treating material surfaces. Some advantages that bioprinting has over these methods is its ability to customize the geometry of the print and produce free standing structures.

Furthermore, while not entirely relevant to our project, introducing potentially bioremediating organisms into the environment can yield some positive effects for future colonization. For example, our cyanobacteria organism removes CO2 from the environment, shifting atmospheric growth conditions to become more like Earth’s atmosphere.

Challenges of ISRU

In-Situ Resource Utilization (ISRU) is the task of obtaining local, natural resources found on celestial planets (other than Earth) to replace raw materials and manufacturing supplies required to support human exploration ([6]). Typically, these raw materials are difficult to transport and require extensive investment, thus hindering astromical exploration. Additionally, if prolonged research is required in space, crew members need access to basic survival resources and supplies, which rely on shipment from Earth. Such needs are especially more difficult to fulfill for explorations of further range; there is an increased cost for transportation and limitation of rocket capacity, not accounting for time-limited dependence on crew members ([5]). This brings about the need for ISRU and the generation of resources from local materials.

Currently, NASA’s Lunar Surface Innovation Initiative has been developing solutions to enable the production of water, fuel, oxygen, and construction materials from lunar regolith ([4]). Some technologies have been tested and implemented in exploration, such as their oxygen and metal extraction, while others have failed due to a lack of funding and insufficient instrumentation compatibility ([4]). Oftentimes, the design ideas are promising, but the lack of knowledge and characterization of local material creates much uncertainty. In an alternative exploration, the Mars Oxygen In-Situ Resource Utilization Experiment (MOXIE) is attempting to test if oxygen production on Mars is viable ([5]). This too requires immense funding, resources, and local terrestrial understanding to properly fulfill.

Overall, ISRU is essential for sustainable space exploration, but it faces several engineering and environmental challenges that prevent large-scale expansion. NASA highlights a few limitations of their ISRU technology ([5]):

• Local resources must be located, extracted, and processed in harsh, uncertain environments that are unlike Earth’s conditions.
• Technology for post-processing must operate reliably in low-gravity and extreme temperature conditions, while also being able to adapt to various material qualities found in local regolith.
• Systems built for ISRU must be lightweight and durable; effective for transportation and maneuvering. With the differing growth conditions in space as compared to Earth, several factors must be taken into consideration, while also accounting for transportation and economic inputs ([6]). This brings about the need for improved systems that can better achieve the goals of ISRU.

Challenges with Printing in Space

While ISRU targets the challenges of using local resources to sustain space missions, 3D bioprinting can be viewed as a complementary technology to this initiative, offering a platform to manufacture biological materials and components directly in space. However, adapting bioprinting to microgravity brings its own set of technical difficulties.

• Fluid behaviour: In a low-gravity environment, surface tension becomes the largest contributing factor when printing in a downwards motion. This makes it difficult to control droplet formation, layer stacking, and bioink placement ([7]).
• Material challenges: Bioinks and polymers may solidify or cure differently in low-gravity and vacuum-like conditions, complicating process control. Additionally, if specific temperature or humidity conditions are required, it may not complement those found on celestial planets ([8]).
• Environmental stressors: Printing systems must withstand radiation, vibration, and wide temperature fluctuations while maintaining precision. With limited materials and time, they must also be reliable and achieve results quickly ([8]).
• Monitoring and automation: As many exploration missions rely on robotics, having real-time sensors and feedback systems enhances the efficiency and ease of printing. This reduces the need for a crew member to monitor defects and adjust parameters ([7]).

Creating Living Building Materials for Mars - the Bioink

On Earth, Living Building Materials (LBM) have been studied as a sustainable alternative to construction materials, especially in reducing $CO_2$ footprint ([9] ). It consists of using construction materials containing living organisms, allowing it to adapt to the changing conditions of its environment. Inspired by the concept of LBMs, we hope to create LBMs suitable for a Martian environment by developing a host of technologies to enable the in-situ bioprinting of construction material on Mars using Martian regolith consisting of soil and rock fragments native to Mars. This will hopefully become a more scalable, durable, and feasible alternative to transporting construction material to build a habitat and sustain life on Mars.

In 3D printing, plastic is being melted and extruded to print a 3D structure. In 3D bioprinting, a biocompatible material that houses living organisms is used, usually referred to as bioinks. We created a bioink that is capable of becoming LBMs on Mars, where by incorporating Synechococcus Elongatus UTEX 2973 with surface displayed carbonic anhydrase enzyme, the bioink can self-mineralize into bricks via the Microbially Induced Calcite Precipitation (MICP) pathway. This bioink serves as a model integrating the 3D bioprinter and the works of our wet lab and dry lab teams.

Here is a brief tutorial video where we demonstrate the methodology shown in the graphic above!

Since this is a novel bioink that has not been tested with martian regolith or our selected chassis, we formulated Design-Build-Test-Learn cycle to address different aspects of bioink optimization. Check out the pages below to learn more about the bioink components and model.

Bioink Composition Testing

Bioink Model Validation

Bioink Calcium Diffusion Modelling