Week 1 HW: Final Project Ideas

Biomanufacturing Customizable Ear Molds with Bacterial Cellulose

  1. What would I like to make and why?

I would like to biomanufacture a customizable ear-mold material for hearing devices using bacterial cellulose. The material could potentially be shaped into personalized ear molds or interfaces for hearing aids.

I am interested in this idea because of my background in biomedical engineering and my previous experience with projects related to hearing loss and biomaterials. I am also interested in developing more inclusive technologies for people with hearing loss.

Bacterial cellulose is interesting because it is produced by microorganisms and has properties such as flexibility, strength, and biocompatibility, making it a promising material for biomedical applications.

  1. What living system would I use?

I would use bacteria from the Komagataeibacter genus, which can produce bacterial cellulose extracellularly.

At a high level, the process would be:

Sugar + nutrients → bacterial culture → bacterial cellulose → purification → shaping → ear mold

The bacteria would grow in a controlled culture and convert a carbon source into cellulose. The cellulose would then be harvested, purified, and processed into the desired shape.

  1. How would I use automation?

For the prototype stage, I would use a liquid-handling robot such as an Opentrons Flex. It could automatically prepare many different culture conditions and test variables such as nutrient concentration, pH, and temperature. This would allow me to run many experiments in parallel and identify the conditions that produce the most bacterial cellulose.

For larger-scale manufacturing, I would use automated bioreactors to control temperature, pH, feeding, sampling, and fermentation conditions. In the future, the experimental data could also be analyzed using machine learning to optimize the production process.

  1. How much would I need and how long would it take?

For a pilot-scale project, I would target 1,000 ear molds.

Assuming each mold requires approximately 2 g of dry bacterial cellulose:

1,000 molds × 2 g = 2,000 g = 2 kg

Using an estimated production yield of approximately 20.69 g/L, I would need:

2,000 g ÷ 20.69 g/L ≈ 97 L

Therefore, approximately 97 L of fermentation volume would be required under these assumptions.

If I used 15-L bioreactors, this would require approximately 7 batches.

Assuming approximately 14 days of fermentation per batch, sequential production would take about 98 days. However, if the reactors operated in parallel, fermentation could be completed in approximately 14 days, followed by purification, shaping, and quality control.

These calculations are preliminary engineering estimates and would need to be experimentally validated.

  1. What don’t I know yet?

The three biggest uncertainties are:

  1. Material properties: I need to determine whether bacterial cellulose has the flexibility, durability, moisture resistance, and acoustic properties required for an ear mold.
  2. Customization: I need to determine the best method for shaping the material into personalized ear geometries.
  3. Scale-up: I need to determine whether the production yield and material quality can remain consistent when moving from laboratory cultures to larger bioreactors.