Development of a Biosensor with the use of an ArduinoFollow project
|1||Arduino, Uno Rev 3 SMD||769-7409|
|1||Seeed Studio Sidekick Basic Arduino MCU Development Kit 110060025 RS Stock No.: 174-3223 Mfr. Part No.: 110060025 Brand: Seeed Studio||174-3233|
|1||ADAFRUIT INDUSTRIES, 1.8in Arduino Compatible Display with Colour LCD Display||124-5444|
SensUs is an annual international student competition aimed at generating new and innovative ideas for biosensors to solve issues with diagnostic testing in healthcare. Our challenge this year is to develop a biosensor to detect the H1N1 flu strain from saliva, to evaluate the local prevalence of flu, but also, most importantly to protect vulnerable groups from being infected by the virus.
Due to the current COVID-19 pandemic, our team has not been able to obtain access to research laboratories or carry out meetings in person. Luckily the Grassroots Student Project fund has enabled us to buy electrical equipment to start our biosensor development at home! We are so grateful for the support they have given us for this project. It has allowed us to begin testing electrical circuit ideas at home and kickstart the development process. The majority of our team members are biomedical engineering students and we have learnt so many new skills in the process of coding the Arduinos and designing circuits. Our project will be continuing until the live competition in September 2021, and we are excited to keep Design Sparks updated with our progress over the next few months. If you would like to stay updated with our journey please follow us on social media:
Influenza background information
Influenza A and B are the viruses responsible for our flu season. Influenza A is classed by two surface proteins: Hemagglutinin and Neuraminidase (Figure 1). There are different subtypes of both these surface proteins. The SensUs competition has tasked us with detecting the Hemagglutinin protein in H1N1, as it is currently available for research but also is one of the most potent strains. Our biosensor should detect the Hemagglutinin concentration levels in saliva to diagnose if a patient has the flu (if the virus is present) and report the viral load.
The Influenza A virus is spherical and approximately 100nm in diameter. Its genome is around 13,500 nucleotides long. It contains 8 single-stranded viral RNA segments which only encode for 12 proteins. Over time as the virus replicates there are slight changes in the genes of the virus and the surface proteins. This creates new variants of the virus. H1N1 is one such variant.
Figure 1 
How can the flu virus spread in humans?
The flu can be transmitted by droplet or contact infection. Droplet infection is when an infection is passed on via air droplets by sneezing, coughing or talking. Contact infection is due to direct contact with an infectious person or surface.
How does the flu enter our cells?
The Influenza virus invades human cells by binding to receptor molecules known as sialic acid found on the cell surface membrane. This binding triggers a series of biochemical reactions which leads to the virus gaining entry to the cell. Once inside, the virus travels to the cell's nucleus, where it hijacks the cell's replication system to create thousands of copies of the viral genome. The cell's protein factories, known as ribosomes, produce viral proteins from the copied viral RNA. New viruses are assembled and these trigger the cell's death as they leave to infect other cells.
Our design idea - aptamers and impedance detection
Our detection method relies on the use of aptamers; these are short polynucleotide molecules (made of DNA) that selectively bind to a specific target molecule with high affinity. At the moment we are considering two aptamer sequences that target the H1 protein  . They can also tolerate temperatures over 60 degrees.
Our aim is to use the aptamers as part of an electrochemical impedance spectroscopy procedure by immobilising it on an electrode surface. The goal is that once H1 proteins bind to the immobilised aptamer, bound molecules on the surface will inhibit electron transfer which will increase the impedance.
This method will enable us to amplify the molecular binding events (the recognition of the virus) into visual signals (electrical parameters). The method offers an easy procedure to quantify protein concentration and the signal can be easily put onto a digital display.
Circuits so far- LCD display
So far, the team has been mainly concentrating on LCD circuits. These LCD displays will be used as the output for the test results. The images below show some of our progress as well as the wiring layout. The first LCD is a 16 x 2 display with a greenback light. This can be used for basic text display.
The Adafruit 1.8’’ TFT shield display can be seen below. It is compatible with the Arduino and the driver. It can display full 18-bit colour text with different font sizes. It is easy to load full-colour bitmap images (shown in Fig.2-2) from a FAT16/FAT32 formatted microSD card, which is placed into the onboard SD card slot. This LCD can be rotated to display in landscape or portrait formats.
The LCD can be used to indicate the progress of the test and display the result as shown in the photos below. This will help with the ease of use by displaying detailed instructions. It will also give the user an indication of how long the test will take. The Joystick button and the other buttons can be used to control the process of the test: for example, starting a pump to move the liquid sample to the measurement system, or adding agents to stop the test.
In the coming months, we will be developing our biosensor research and circuitry further. Our next goal is to create circuits for the sensor control such as pumps to alter the fluid flow. We will also be developing the impedance concept with the use of circuits. We are also considering adding a thermometer element to our design, as most flu patients experience an elevated temperature. We will be adding some accessibility features to our user interface design such as the ability to increase the text size or have audio test instructions.
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