Why Digital Interface?
While some radical biodesigners criticize proxy interfaces that mediate human-biology interaction, we believe a step-by-step learning process is essential. Therefore, we designed KojiGotchi to offer partial direct engagement through metabolic symbiosis and smell, but we still provided a digital interface. This interface facilitates the crucial learning process, helping users understand the subtle needs and cues that koji provides, making complex biological interactions approachable and comprehensible.
Journey towards koji
Our journey began by seeking the perfect microbial partner. We initially explored well-known biomaterials like bacterial cellulose (BC) from kombucha and mycelium, even consulting specialists like Vivien Roussel, Andrew Adamatzky, Davin Browner, and Adrien Rigobello. We learned that the beauty of these materials often lies in their minimal human intervention; they thrive at room temperature and are highly resistant to contamination, demanding little effort. While an early concept involved using a PicoLogger to translate mycelium’s electrical activity into language, this proved impractical due to the need for a Faraday cage and highly accurate sensors, which would compromise our goal of accessibility. Similarly, kombucha’s requirement for a static culture to form cellulose meant a lack of dynamic engagement. This desire for active interaction, combined with the expertise of our supervisor Dr. Joshua Evans in koji, ultimately led us to select Aspergillus oryzae as our ideal microbial companion.
Anti Clean Aesthetics
With the Tamagotchi format and koji selected, our team moved to the drawing board to define the KojiGotchi’s aesthetic. We debated various directions: would it be the stereotypical clean, alien biodesign look, functional Scandinavian, or something more playful, akin to Teenage Engineering? Ultimately, we landed on a blend heavily inspired by Y2K and vaporwave aesthetics, a deliberate homage to the Tamagotchi’s era. This choice also serves a larger purpose: to highlight the rich plurality of aesthetics that can thrive within biodesign, moving beyond the often homogenous, Oxman-esque styles that sometimes feel like a futile antidote to public reluctance towards microbes.
Testing the Human Incubator
After settling on koji as our organism of interest, the next crucial step was testing the feasibility of using the human body as an incubator for its growth. Our initial experiment was minimal: we placed steamed rice inoculated with koji spores into a simple Ziploc bag and carried it in our back pockets for 48 hours. While we observed a small amount of growth, overall success was limited. The simplicity of our setup, however, made it challenging to pinpoint exactly why the growth wasn’t thriving. This inconclusive result prompted us to significantly upgrade our experimental setup for the next iteration of testing.
Proof of Concept
For the next iteration, we significantly upgraded our setup. We 3D printed an egg-shaped container, placing a commercial air temperature sensor in its upper compartment and the rice with koji spores in the lower. We then carried this prototype for about 60 hours, suspended under the armpit and in direct contact with the body, while maintaining normal daily activities in an ambient temperature of approximately 16°C. This experiment was a clear success: it yielded a piece of rice koji as fragrant and tasty as those produced using traditional incubation techniques.
Safety & Engagement
After proving koji could grow with just body heat and minimal equipment, we faced our next challenge: how to design a product offering a safe, engaging learning experience. To answer this, we needed to understand the key variables impacting koji’s well-being and whether sensors could capture them.
We prepared an experiment to track koji’s growth with various sensors. We first measured its basic needs: temperature, humidity, oxygen, and rice moisture. We also learned that overheating inside the rice clump made koji prone to contamination, so we included a temperature probe. Finally, since mold color is a crucial visual cue for contamination, we implemented an RGB sensor. You can check a full breakdown of this experiment on the Experiments page.
Visual Feedback
To address the challenge of accurately reading koji’s color with a sensor, we sought an alternative: designing the growth chamber from transparent polystyrene, produced using a vacuum former. We were pleased with the result; the food-grade polystyrene not only provided excellent visibility but also significantly increased user engagement by allowing direct observation of koji’s growth. However, this decision introduced a new hurdle: our device assembly now required an additional piece of equipment beyond just a 3D printer. We are currently exploring workarounds to maintain the KojiGotchi’s accessibility.
Carrying your pet
Beyond the internal technology, a key challenge was figuring out how users could keep their KojiGotchi close to their bodies for optimal growth. We experimented with numerous harness designs, each unique and suitable for different situations, body types, or personal styles. Instead of settling on one fixed design, we opted for a more flexible solution: we integrated three versatile hoops into the KojiGotchi’s casing. This empowers users with the agency to choose and adjust their preferred carrying method, truly adapting the device to their individual needs and desires.
Future Extensions
For future iterations, we envision implementing an atomizer. This feature was part of our initial brainstorming but was set aside due to time constraints and the added structural complexity it introduced. However, our experiments clearly showed that amplifying koji’s distinct aroma is crucial to highlighting its livingness even further. We also believe an atomizer would make sharing your koji’s progress a much cooler and more engaging experience with others. If you have any other suggestions for extending the KojiGotchi’s capabilities, please let us know!
Sentiments towards koji
We concluded our journey with a two-part user study: an interactive session and an online survey. The interactive session allowed us to observe people’s direct engagement with our device and their sensory responses to koji. The online survey, meanwhile, sought a broader understanding of public perceptions concerning fermentation and microbially-powered technologies.
One striking finding revealed a significant disconnect: while 90% of our 41 online respondents expressed curiosity or comfort with technologies powered by their own metabolism, very few were actually willing to touch koji again after learning it was moldy rice. This was true even among those who dreamed of wearing a living mycelium jacket someday! These results powerfully reinforced our conviction that the gap between public curiosity and actual microbial understanding must be bridged.
Education & Open Innovation
With our findings in mind, we envision the KojiGotchi making a significant contribution to microbiology and fermentation education, particularly in primary schools. Why should children only learn to care for plants and not for microbes? Our device aims to change this, offering a tangible, engaging way for young minds to connect intimately with the microbial world around us.
Beyond formal education, we’re keen to include the vibrant Maker and Biohacker communities in this conversation. By making our device 100% open source, we hope enthusiasts worldwide will contribute to optimizing its parts and materials. We also invite them to adapt the KojiGotchi for entirely new applications or even different organisms, fostering a truly collaborative and innovative future for biodesign.
