Team:Cornell/testing/project/drylab/3

Functional Requirements

In the development of our device, we first had to establish a set of requirements and constraints.

What sets these constraints? Our ambitions and our "customer," the Wetlab Team.

We sat down with them and came up with the following:

1. The device must operate independently for at least 6 months.
2. The device must be based around an established Shewanella onidensis bioreactor setup for Arsenic and Napthelene biosensing..
    a. Reactor size must be 100mL in volume
    b. Reactors must have 3 electrodes; 1 reference, 1 working, 1 counter.
    c. The potential difference between electrodes must be measured by potentiostat, or an equivalently performing device.
    d. The electrodes should have maximum surface area inside the reactor.
    e. The electrodes should be in closest proximity without touching.
3. The bioreactor must remain free from foreign microbes; incoming analyte must be cleaned from foreign microbes.
4. Waste water must be microbe-free upon ejection.
5. The device must be field-deployable.
6. The device must store and transmit measured data remotely.
7. System components should be modular, for ease of servicing, and interchangeability.

From these requirements we listed out parameters, split into research groups, and began trying to develop some solid constraints. What did "field-deployable" mean to us? How were we going to transmit data? Or what did 6 month independent operation entail?

We needed to establish our base constraints, and base components. To answer these questions, we began to perform research and engage in brainstorming. The team was divided into "Component Teams" - Each component team would be responsible for researching some aspect of the design (power, inputs, pumps) and become the expert on their piece.

The mind map below illustrates the parameters we associated which each base issue.

Concept Generation

After defining the functional requirements for the biosensor device, Dry Lab members held a general brainstorming session to pool ideas for various aspects of a system that could sustain bacterial culture and immerse the microorganisms in a water source without contaminating that reservoir.

First, we were assigned broad topics relevant to the system, such as pump, food delivery and power source. Working individually or in pairs, members listed and sketched ideas with open minds. We then silently exchanged our notes and made comments on Post-Its; this method allowed everyone to have a voice in each topic. After all comments and questions were written down, notes and sketches with accompanying commentary were returned to respective members so that they could briefly build off of the critique. We then took turns explaining, clarifying and even questioning our ideas to the rest of the group. At the end of the general session, we had a good sense of direction for each topic.

Outside of the team, we individually researched products and designs corresponding to our assigned topics. We prepared presentations of three designs that emphasized different desirable qualities, such as high efficiency, light weight or low cost. At following brainstorming sessions, we exhibited these designs, and followed up with questions and comments. We repeated this process for a series of meetings in order to refine and find concepts that best satisfied the functional requirements.

Primary Components and Constraints

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Secondary Systems

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Potentiostat Section content

Chassis Section content

Server Section content