Team:EPFL/Implementation

• Who uses Espress'EAU?
• Delivery and pick-up system
• Is Espress'EAU safe?
• Waste management
• Future challenges

Espress'EAU - Proposed Implementation

Espress'EAU is a system designed to test water samples for general water quality. The device will be the size of a shoebox and needs an outlet for power supply. 5 ml of water is added with a syringe to a reusable capsule that contains freeze-dried genetically modified yeast and growth medium in powder form. The capsule is placed in the device which measures cell density and a fluorescent signal. A small stirring magnet inside the capsule allows the creation of a vortex that mixes the powder, the yeast and the water sample and keeps the cells in suspension. The measurement will take a few hours.

After the measurement is finished the data will be analyzed on a server and the user will be notified about the results and a green or red LED light on the device will indicate a possible reduction in water quality. The user will return the capsule to the manufacturer who takes care of waste treatment. In case Espress'EAU detects an irregularity, the user is encouraged to run further tests to determine the source of the contamination.

Who uses Espress'EAU?

Espress’EAU is intended to be used by small communities that do not necessarily have their own laboratory for water quality testing, and therefore depend on water testing facilities. We learned in an interview with Quentin Morezzi, who is responsible for the water supply of small villages around the city of Lausanne, that samples are transported from small communities into centralized private or public laboratories where they are tested. With the Espress’EAU device, the responsables for water quality in small communities will have the opportunity to run a preliminary analysis which does not involve transportation to a central laboratory, allowing them to have these tests more frequently. Thus, Espress’EAU has been designed in a way that it can be handled by users that are not necessarily trained to do lab work. The display of the results also needs to be comprehensible for both experts and non-experts.

Furthermore, Espress'EAU can be used by any individual that wants to have an idea about the quality of the water they are drinking and using to cook. The device was designed on an open-source basis and all 3D models and the software are available on our github. Anyone can rebuild the device, given access to a 3D-printer and a soldering station. Certain parts of the device, such as the OD₆₀₀ and fluorescence sensor, can also easily be repurposed to create low-cost lab-equipment.

Delivery and pick-up system

To implement Espress’EAU in the real world, the manufacturer would need to establish a delivery and pick-up system. The users order batches of capsules containing freeze-dried yeast and medium powder. After use, the capsules are returned to the manufacturer who disposes the biowaste, autoclaves the capsule and prepares it for the next user, thereby creating a sustainable cycle and producing minimal waste.

Is Espress'EAU safe?

The Espress’EAU capsule contains genetically modified yeast to enable the detection of water contaminants. Although there is no immediate risk to the user’s health, this GMO should not be released into the environment. Therefore, the user does not need to take care of the disposal of the cells and the capsule, but he can simply return them to the manufacturer after usage. To make sure that even in case the user drops the capsule there will be no threat to his or her safety, the design was conceived to be leakproof and robust. Several tests were made to ensure that even if the capsule happened to fall from a table-height surface, no liquid is spilled. Still, to lower the risk in case of a broken capsule, we plan to end our measurement protocol with a fatal heat shock at a high temperature to inactivate the cells. The hardware was also designed to avoid the overheating of the Peltier element, using a MOSFET as safety circuit.

Is Espress'EAU safe?

The Espress’EAU capsule contains genetically modified yeast to enable the detection of water contaminants. Although there is no immediate risk to the user’s health, this GMO should not be released into the environment. Therefore, the user does not need to take care of the disposal of the cells and the capsule, but he can simply return them to the manufacturer after usage. To make sure that even in the case the user drops the capsule there will be no threat to his or her safety, the design was conceived to be leakproof and robust. Several tests were made to ensure that even if the capsule happened to fall from a table-height surface, no liquid is spilled. Still, to lower the risk in case of a broken capsule, we plan to end our measurement protocol with a fatal heat shock at a high temperature to inactivate the cells. The hardware was also designed to avoid the overheating of the peltier element, using a MOSFET as safety circuit.

Waste management

Every part of Espress’EAU has been designed in order to make our device as eco-friendly as possible. Apart from the plastic syringe that is used to inject the water sample in the capsule, there are no disposable components. Every part of the hardware design is reusable several times. Glass vials were chosen for the capsule as they are autoclavable and resist more uses. The silicone disk on top of the capsule cap was tested in order to ensure that it can be pierced several times by the needle used for pressure equilibration without visible damages. As a future implementation, one could imagine switching to glass syringes that could be cleaned and sterilized like the capsule, making 100% of the components reusable.

Future challenges

Several challenges still have to be faced in order to reach this proposed implementation. First of all, a lot of work is still required to transform the prototype that was obtained into a fully functional and commercialisable product. Freeze-dried yeast was chosen for our device as it facilitates transport and storage of the cells. As the modified yeast is supposed to be shipped in freeze-dried form, the shelf life has to be evaluated in order to guarantee the quality of our detection system. The biggest challenge that still persists is to increase yeast sensitivity to match the Swiss legal thresholds for pesticide traces in water. Indeed, this concentration (1 μg/L) is very low and would need further and more sophisticated genetical modifications.

Special thanks to our sponsors!

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