Team:FDR-HB Peru/Hardware

FDR HB - Hardware

Hardware

Description

Here at hardware we designed the material parts for our project to succeed. We have been designing a bioassay that incubates the bacteria and allows detection of cadmium in the fishmeal products that have been diluted into the bacterial liquid. The bioassay is handheld and designed for maximum mobility and efficiency. In short, a small cadmium biosensor that any fisherman can use to test the quality of his fish. We also created an instruction set in order to allow the workers to be able to use the system safety with an understanding that they are working with bacteria and how to follow the proper disposal methods after using the bacteria.

Importance of field work

Our bioassay is to be fully designed and equipped for field use. Why is it so important to use it in the field?, you may ask. Fishing companies (such as TASA) need early detection methods because a lot of time and money is wasted on processing and bagging the contaminated product. With our bioassay, fishermen on the boat will have the chance to determine the contamination grade of the fish at an early stage, saving the company valuable resources.


The larger problem is within the realm of regulations. There are very few fishmeal importers that will accept a product with more than 2 parts per million (ppm) of cadmium. Our whole project is centered around helping peruvian fishing companies reduce their average cadmium content.

Research

Doing research for the bioassay’s characteristics was a long process. First of all, we had to research about the materials we would use. We would 3D print the model, so PLA plastic was the final choice for the prototype. This material would allow the bioassay to survive in most required environments, more specifically in a fishing boat. However, we plan to use stronger plastics in the future.


Bacteria need a warm and dynamic environment to grow. This is why we thought installing a heater and a shaker in the bioassay was essential to the success of the project. Regarding the heat problem, we first thought we needed to build a circuit that regulated a heater’s voltage in function to the bioassay’s temperature, which meant we would need to install a digital thermometer to provide this information. We didn’t want to kill the bacteria with extreme heat, so we would set the target temperature at the optimal bacteria breeding temperature: 37 degrees Celsius. We later learnt these circuit sets already existed, and we bought a set after endless hours of looking on Amazon.com and similar online stores.


Regarding the shaker, we first thought an offset configuration using a conventional motor would suffice, but there wasn’t enough stability in the system. Instead, we opted for a three-point ball bearing configuration that used a stepper motor. We have yet to 3D print the configuration.

Design of the orbital shaker

We based our orbital shaker in a design we found online (https://www.thingiverse.com/thing:2633507). We used this design as a base and started modifying it to suit our needs.


We introduced a self-regulating heater to keep bacteria at an optimal temperature (37°C). The temperature regulator will turn off the heater when the temperature surpasses this temperature, and it will turn the heater on when the temperature drops below it. The heater will go in the middle of the upper part of the orbital shaker. See image 1 below for the wire diagram.


We also remade the upper part of the orbital shaker, so it can hold five tubes. Each tube will test for a different concentration of cadmium, 1 PPM, 2 PPM, 3 PPM, 4 PPM, and 5 PPM. This part along others were 3d printed. Image 2 is this part of our bioassay.


To ensure a safe disposal of the bacteria we came to the conclusion that two bleach buckets needed to be added to the sides of the shaker. One to dispose the medium with the bacteria and the fish mush, and another one to the tubes after they have been used.


To keep light from entering the bioassay we decided to encapsulate the upper part of the bioassay to achieve this.


Last but not least, we decided to power the orbital shaker by using a 12V battery. This way the shaker can be taken on boat trips by fishermen.


1. Wire diagram of heater, heater regulator, and motor.

FDR HB Hardware 1

2. Upper part of the orbital shaker.

FDR HB Hardware 2
FDR HB Hardware 3

3. 3D printed parts

FDR HB Hardware 4

Future Steps

What we would like to do in the coming year is to test our bioassay, in order to improve it and implement it with the fishermen. Our testing will include:


  • A growth curve to ensure that the bacteria can reproduce normally while the bioassay is functioning.
  • An experiment to test the effect of heating the PLA up to 37°C constantly.

After we finish testing and the modifications that need to be made are made we will build the orbital shaker that will be given to the fishermen.

Bioassay

FDR HB Education Picture 1

The motor is used to shake the upper part of the bioassay in order to make sure the bacteria is able to obtain enough oxygen to work properly, the battery is just supplying power to the motor and heater which is connected to an arduino chip that has an lm35 temperature addition in order to monitor the temperature and keep the heater from heating the inside up past 37º C. The tubes merely contain the bacteria in medium with the fish added inside as soon as it’s ready to be tested. The Bleach waste buckets are in order to ensure there is minimal biohazard risk. It provides an area for the bacteria to be temporarily disposed of until the bioassay is off the fishing boat and the bleach containers are able to be dumped out. There will be multiple sets of 5 tubes in order to allow multiple tests throughout the fishing trip in order to ensure as reliable results as possible.


The motor shakes a part of the container, which is heated to 37 degrees. This ensures a quick, optimal breeding environment for the bacteria to detect cadmium.


Videos

Shaker Component

Bioassay Hardware with shaker and temperature control

Most recent prototype of our bioassay

Instructions

WARNING: YOU ARE WORKING WITH A BIOHAZARD!

  1. After use of the bacterial liquid, pour all the contents of the tubes into the bleach waste bucket and let them sit for a minimum of 5 minutes.
  2. Rinse the tubes with bleach and let them sit for 5 minutes before rinsing them off with water.
  3. Do not reuse tubes with bacterial liquid until the tubes are autoclaved.
  4. Dispose of bleach liquid after trip, the liquid should be disposed down a sink or other disposal system.
  5. Place any used tubes in a safe area on the boat where they will not move or be disturbed.

ADVERTENCIA: USTED ESTÁ TRABAJANDO CON UN PELIGRO BIOLÓGICO

  1. Después de trabajar con el líquido bacterial, vierta todo el contenido de los tubos en el contenedor de basura 1 y déjelos enjuagar por al menos 5 minutos.
  2. Enjuague los tubos con lejía y déjelos ahí por 5 minutos antes de enjuagarlos con agua.
  3. No reuse los tubos que hayan contenido líquido bacterial hasta que esterilice con autoclave.
  4. Deshágase de la lejía contaminada en un lavadero con bastante agua u otro sistema de limpieza.
  5. Ponga los tubos usados en un área segura en el barco en la que no se muevan o sean perturbados de alguna manera.
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