Harvey Mudd College has a clinic team with AMYBO! This is where we will be posting our summarized meeting minutes so the larger AMYBO community can see the progress of our project.
Please feel free to reply with comments/suggestions!
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1/24/2025
Subteams: anode, and pinch valve.
This semester, we will be continuing to test different anode materials to find the best balance between safety, effectiveness, and reproducibility. In our research, we found that the most effective anodes are made of various alloys, which we will be testing in the upcoming month. We are considering a nickel alloy, though there are safety concerns associated with ingesting the material. Additionally, as the platinum used in previous experiments has been determined not to be real (or at least pure) platinum. We will work to source some pure platinum so we can plate and test a 3D printed structure as our anode. The solenoid pinch valve team determined last semester that a 5V solenoid cannot produce the force required to pinch the tubing shut, and will be switching to a 12V design. We will be looking into finding an off-the-shelf component that meets our requirements, and, if one cannot be found, will design our own based on our CAD model from last semester. In addition, once the pinch valve deliverable has been met, we intend to transition to our stretch goal of converting the Pioreactor into a flow through cell. This will likely be done in parallel with materials research for the anode, given the breadth of that task.**
On anodes - will you still be investigating graphite? And have you subscribed to this thread on anode material?
On the pinch valve - am I correct in understanding that it is an off the shelf 12V solenoid that you aim to procure to combine with your pinch valve design from last semester?
We are planning on finding an off the shelf valve and modifying it to work better for the application necessary for the pioreactor. If we cannot find one that meets our constraints, we will modify our current design to fit a 12V solenoid. We will not be modifying an off the shelf valve to work with last semesterās design. I hope this clears up any confusion!
1/28/2025
The valve team will begin designing an open-source solenoid pinch valve. The anode team has obtained nickel to test and will also begin testing the graphite for fouling using the HOB acquired last semester (they will likely need to attempt to grow the bacteria using a known anode first, to make sure the sample has HOB). If there is no HOB in the sample, we will source some either from NCYC, or another freshwater source near campus.
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Ah, sorry. Did I mention NCYC - thatās a UK based culture collection. There is bound to be one much nearer to you that would have model HOB. Itās possible that Harvey Mudd already have someone with Cupriavidus necator or a suitable Xanthobacter, etc.
2/4/2025
Valve team: Solenoids have arrived, and we are in the prototyping phase: each subteam member will come to the next meeting with 1 design to present. From there, we will test each design and, at the following meeting, present our results.
Anode team: Tested a nickel anode with a stainless steel cathode. The resulting current density was higher than previous metal tests, but dropped off rapidly. There was also residue in the water (possibly rust) as seen in the attached picture. We are also researching 3D print electroplating to meet our ease of manufacturing constraint (otherwise metal rods would likely have to be machined). We are also looking into titanium electroplating. We will be getting deionized water for future tests and confirmation that the residue in the water is a result of unwanted chemical reactions with water pollutants. Niobium based alloys are also a potential solution. We would need to consider oxidation.
HOB Purchasing: Will source Xanthobacter Flavus from USDA ARS Culture Collection. If this is not possible, we will reach out to professors using the strain and ask for a sample.
Thanks for the update! Can you share where you sourced your nickel anode and stainless steel cathode or their specs?
What were your voltage and current settings during electrolysis?
Hi Gerrit!
We purchased the nickel anode off of amazon rated to be 99.6% nickel and was highly reviewed. Here is the link to that: Amazon.com: SHONAN Nickel Anode- 7.87"x0.3"(Diameter) Nickle Anode, Pure Nickel Bar, Nickel Rod for Nickel Electroplating Solution, 3.4oz 99.6% : Industrial & Scientific
The stainless steel cathodes are just stainless steel bolts we got from our in house stockroom at Mudd. The specifications I could find are as follows: stainless 67? I was under the impression that any stainless steel bolt would work fine but if you have more specifications we should follow, weād be happy to purchase something else.
The voltage setting is on 5.00V applied voltage and then it is on a current readout setting so rather than setting that, we are reading the values which were 13mA, 6mA, and 4mA through a 24 hour test period while testing the nickel anode.
Thanks for the link, it may help others who would like to replicate the setup!
@Martin has been looking into different types of stainless steel - our preferred option is 316, which is corrosion-resistant. Thereās also a low-carbon version called 316L.
Iāve been using 304 grade without any issues, but I canāt say Iāve heard of stainless steel 67 before. That is quite a large amount of sediment in the picture - is it possible the positive and negative were swapped and the stainless steel electrode was oxidizing? How long did you run it for?
Have you tried connecting the electrodes to the Pioreactor and running it at 10% intensity?
Yes, I would say that 316L is the preferred grade (see this post), but I found it difficult to source suitable 316L bolts in the UK as they tend to be sold as āA4ā which is defined by Westfield Fasteners as:
āA4 Stainless Steel - Also known as grade 316 or 18/8/3. A higher corrosion resistant, marine grade of stainless steel.ā
I believe A4 may be 316 or 316L (low carbon). My plan, if A4 was insufficient, was to move to Duplex which is most likely overkill, but it is at least a grade that bolts are sold in. Given that Gerrit has been using 304 (aka A2) without issues, the assumption is that A4 should be more than sufficient.
Thanks for all the info!
We are currently running a test with deionized water + sodium bicarb to ensure the issue isnāt the water on campus. Then if we are still having issue we will look into getting the stainless steel you recommend and switching the anode and cathode. We arenāt seeing much rust on the electrodes themselves which is what has us suspicious that it may be the water. We will update with more soon.
Thanks!
2/11/2025
Summary:
Valve Team: The valve team is in the prototyping phase. The three designs selected are below, and will likely be modified to work horizontally, rather than vertically, such that the valve can be as close to the vial cap as possible. This is to minimize backflow into the tubing. Additionally, the solenoids selected have an initial pull-up force of 12N, and a keep force of 60N. However, the spring holding the solenoid in its normally closed position does not apply the 10N required to hold the tubing closed. We are in the process of finding a spring with the necessary specifications such that the tubing will be kept closed when the solenoid is not powered.
Anode Team: We put sodium bicarbonate into our water to deionize it and run tests. This worked very well for the graphite-stainless steel test (pictured below) as there was no color change as seen before. However, for the nickel-stainless steel test, there was a large amount of orange residue in the water (also pictured below). Platinum is accessible to us, however, the lab lending the material advised us to find the cause of the residue before testing such a high cost material. The first test will be to run the experiment with anodes and cathodes of the same material (this isolates stainless steel). The three materials we will be moving forward with are graphite, nickel, and platinum. There was some discussion about niobium, however, due to its high cost, it does not fit into the constraints of the project.
Apologies for the string of replies. I can only attach 1 image to a post
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Hi @Madi & Team Anode, as promised, hereās the conversation I have had to date with ChatGPT o3 in Deep Research mode. Please take this with many grains of salt, it misunderstood a fair few things. I mainly raised it to get your take on the HF etching:
Initial prompt:
Can you please produce a manual on how to optimally platinum plate a 35mm end of a 60mm length 6mm diameter titanium rods so that they can be used as in-culture electrodes for hydrogen oxidisation bacteria cultivating in an electroPioreactor?
The main focus is going to be doing repeatable HOB experiments, so we need to be able to have the same surface area, platinum thickness, current density, etc. in multiple experiments conducted across the world, with different people electroplating their own titanium rods, all using different suppliers. It is important that we can make these experiments reproducible so that when comparing them, we are comparing the differences between HOB strains rather than experimental setups.
I already have a āD03232 POWER SUPPLY, 1CH, 15V, 2A, ADJUSTABLEā and glass beakers, so please determine whether these are sub-optimal, and if so what I would be better with and why. Please also indicate if they would suffice (in order to minimise total cost).
Please start the report with a tools and materials section listing all tools, equipment, consumables, etc. that will be required and can be purchased in Scotland, along with their approximate cost. For any items costing more than Ā£10 please provide the top three procurement links, for any items costing more than Ā£50 please provide the top ten procurement links. Please bundle any items priced under Ā£10 so they can be purchased from a single manufacturer and provide three manufacturers with the price for each item, total price and shipping cost.
Please provide a section detailing how we can produce 12 matched electrodes that can be used in academic comparative trials. Identical electrodes is the main objective of this section, cost isnāt a major concern here.
Please also provide a section detailing how we can produce 2 matched electrodes using an electroPioreactor. In this section cost is the most critical factor, if itās possible to do the electroplating just with the electroPioreactor and no bench power supply, that would be a bonus, but please do mention any benefits of using a bench power supply.