Hardware

This page takes you through the complete development of LuMOO’s detection device, following the complete engineering design cycle including our initial concept and prototype construction to rigorous testing, each stage offered insights into areas for improvement. This iterative process of designing, learning, refining , and redesigning has shaped the final version of LuMOO.

Detection Kit

Biosensors are increasing in use across different industries including disease detection, quality control, and forensics. Among the various types of biosensors, each offers unique advantages and faces specific challenges. Bioluminescent biosensors translate light emitted by biological interactions into a readable signal. However, they can be expensive and complex to operate. LuMOO aims to address these limitations with the hopes of being a cost-effective bioluminescent device designed to detect the light emitted from the interaction of Split Luciferase-Encapsulin fusion proteins (Part BBa_K5330020 and Part BBa_K5330021). Specifically tailored for farmers, our LuMOO detection device is compact, portable, and capable of quickly delivering results, with easy data transfer. This rapid reporting system aims to eliminate long waiting times, making it a practical tool for on-site detection and a faster response from the farmer to correctly address their cattle.

What Makes Up Biosensors?

A typical biosensor consists of five key components: the analyte, bioreceptor, transducer, electronics, and display. The analyte is the target substance being detected, while the bioreceptor specifically binds or interacts with it. The transducer, converts this interaction into a measurable signal, typically electrical. This signal is then processed by the electronic system and presented as readable data on an external display. Optical biosensors, utilize a technique called luminometry, which converts the light detected into an electrical signal (2).

Luminometry

Luminometry measures light by quantifying the number of photons striking a photosensitive surface. Devices such as photoresistors, photodiodes, and phototransistors serve as transducers that convert light into electrical signals (2). Unlike fluorometry, luminometry does not require an external excitation source to produce a glow in the analyte, simplifying the hardware design and making it a more efficient solution for many biosensing applications.

How Will Farmers Use This Kit?

Farmers will take a blood sample from the cow, place it in an microcentrifuge tube with the LuMOO MAP Encapsulin containing assay. They will then place the tube in the kit and place the lid back on to completely eliminate any light contamination. They will then put the cow number into the keypad and the results are saved on the device and can later be uploaded to a spreadsheet.

Figure. Diagram of LuMOO detection kit and its components.

Circuit

The LCD screen serves as the primary interface for displaying positive and negative results, while the keypad allows users to input the cow’s ID or sample number. These results can then be automatically sent to a spreadsheet for record-keeping. At the heart of the device is the Arduino UNO R4 Wi-Fi, a low-powered microcontroller with built-in Wi-Fi capabilities, serving as the system's main electrical component. The MCP23017 expansion interface plays a critical role in connecting all the parts to the Arduino. By providing additional input/output options, it streamlines the wiring process and ensures that all components are seamlessly integrated. The TSL2591 photodiode is the most crucial component of the device. After discovering that the photodiode used by the 2021 iGEM Calgary (1) team was no longer available, we consulted with a professor and adopted the TSL2591. This photodiode converts incident photons into a readable signal and produces a square wave output (50% duty cycle), with the frequency directly proportional to the light intensity. Its digital output can be interfaced directly with a microcontroller, making it an ideal fit for our device. This schematic shows (figure 2) a simplified version of the wiring used to program all the device parts together. It included all the new changes that were adapted over time to the device to make it more seamless and efficient.

Figure. Schematic diagram of detection kit layout.

Software

The Arduino microcontroller can be programmed with C++ on the Arduino IDE, then the data is transferred onto an SD card which can be read as a CSV or Excel file. Due to the new Arduino UNO R4 Wi-Fi that was used, the libraries for keypad had to be adjusted. Sleep-mode was also incompataible with this version of our Arduino as no libraries were written. Older Arduinos have sleep-mode which can be programmed to allow an on/off system. We adapted a latching switch to avoid this problem allowing the device to turn on/off through the battery rather than via the Arduino. The link to our software can be found here.

Hardware Overview