Third Year Project - Temperature Control of a Water Bath
My third year dissertation was based on a practical project. My supervisor was very much involved in bioelectronics, in particular the
Open Scientific Hardware movement.
I self-proposed an idea for using an immersion circulator to heat biological samples, much like the ones used in professional kitchens for cooking food
'sous-vide'. The project developed and evolved until it became what it is today, a low-cost, accessible, open-source, non-circulating water bath.
Due to the coronavirus COVID-19 outbreak, the traditional viva oral presentation was not possible, so I instead submitted a video explaining the functionality
of the design. Which can be seen below.
The design process of the report is shown below. It's a condensed version of the information that is available in my dissertation.
If you'd like to download a copy of my dissertation, please click here
Design Overview
Dissertation Abstract
A project investigating the design of a low-cost, accessible, open-source water bath for the heating of biological samples.
This includes a literature review of current open-source scientific equipment, and the creation of a realistic specification for the water bath.
The project determines whether the techniques found in other open-source projects can be applied to the design of a water bath.
A flat plate mica heater is used to heat the water, and a PT1000 two-wire sensor is used to provide feedback to the control system.
An investigation of how heat conducts through different materials is also made.
The viability of the finished bath is assessed through the construction of graphs to show how the water in the bath heats up over time,
with the final conclusion being that although the water bath does not meet the original specifications, this is due to extenuating safety factors,
and not the design. Where experimental investigation is not possible, the results are modelled using equations and existing results.
Bath Construction Steps
I designed the casing for the bath on Solidworks, this allowed me to fit all the pieces together on a computer to make sure they fit before I laser cut them.
I bonded the laser cut pieces together with a solvent (Anglosol 1200), which melted the bath sides together, ensuring a waterproof seal.
The gap in the bottom of the bath is filled by a metal plate, this ensures good heat conductance from the heater to the water,
while ensuring a good seal so that the bath doesn't leak.
Unsurprisingly, when I told the lab techs that I wanted to mix a 260℃ heater, with 230V mains AC, and a half litre of water,
they weren't completely on board with the idea... So I had to turn down the input voltage to 60V. I did this by using this beefy piece of kit.
It's called an autotransformer and it makes you feel like a mad scientist. I had to set the limit to 60V, which had a fairly huge impact on the bath's heating ability.
There are graphs showing it in my full dissertation, which you can get by clicking on the link above,
but effectively I went from a heater temperature of 260℃ to one of 55℃ .
So, this is the final product! All powered by an Arduino Mega. The grey wire is the temperature sensor which has its value read by the Arduino.
All the data is output to the LCD display (C). The box containing the relay (D) is fully waterproof, so that if any water does spill,
it can't get access to mains voltage. The Arduino is powered by a portable battery (A).
When the temperature sensor says that the water is too cold, the relay is turned on. When the user's set temperature (B) is reached, the relay is turned off.
Fourth Year Project - Low-Cost Level Sensing For Domestic LPG Canisters
My fourth year Masters project was a group project with a brief an external industry partner.
We designed and built a level sensor for LPG 'Calor' gas canisters. A Bluetooth connection between the sensor inside the canister and a box mounted on the outside relayed the level state. This was then relayed over the LoRa network (The Things Network) to a mobile app developed using Ubidots.
If you'd like to download a copy of my masters dissertation, please click here
A copy of the accompanying poster can also be downloaded here
Design Overview
Dissertation Abstract
This project aimed to design a bench-prototype of a relatively low-cost LPG level
sensor. The purpose of this project was to aid LPG rental companies in reducing
the number of customers calling when needing to replace their LPG cylinders.
The end product consisted of two main components; an internal level sensing module,
and an external communications module. The internal module was a battery, and
Bluetooth microcontroller housed within an in-house made float sensor.
The external system was a strip board with all the modules required for communication,
including Bluetooth and LoRaWAN. In order to achieve communication between
the internal and external systems, Bluetooth Low Energy was implemented. A
satellite navigation device was used externally to obtain the location of the LPG
cylinder. A LoRaWAN module was used to upload all gathered information to a
cloud database.
This project tested and demonstrated a bench prototype of a fully working system,
which was within budget. This report discusses all research and testing, and evaluates
the results demonstrating the success of the project. This report also discusses
further work required to progress to the next stage of development. Project management
techniques used are also discussed, including the mitigation of the effects of COVID-19.
