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Automated solubility measurement system
Final Design Solution:
The entire system consists of three individual LEDs (light emitting diodes), two TCS34725 RGB color sensors, one DS18B20 temperature sensor, Masterflex peristaltic pump, the black box, a magnetic stirrer, the conductivity probe, 100 mL circular beaker, an Arduino UNO, the Raspberry Pi, solid delivery system, and the computer for data acquisition and control system. The experiment starts with oversaturated solution, then adding more solvent using the pump, and necessary solute with solid delivery system into the solution to reach the saturation point. The solid delivery system consists of the stepper motor that opens the door to solid solute container, and drops the solute into the solution when the solution is undersaturated.
The conductivity probe is connected to an Arduino UNO, while other sensors, magnetic stirrer, and the peristaltic pump are connected to Raspberry Pi through GPIO pins and USB cables. Furthermore, a PCB design is used for the circuit of the temperature and RGB color sensors. Users use Ethernet and enable SSH to access the command line of the Raspberry Pi remotely from the personal computer. Therefore, users can enter commands and run the python code files with their computers to control the Raspberry Pi.
Inside the black box (enclosed system), one RGB color sensor is placed near the middle of the beaker, while another is mounted overhead the beaker to measure RGB component of the LEDs. The data outputs from two RGB color sensors are compared with tolerance to examine the saturation point is reached when the data outputs are similar. In order to facilitate the dissolving of the solute and to reduce noise for the RGB sensors, a magnetic stirrer is used to agitate the system. The temperature sensor monitors the change of the temperature during the experiment, so users know that the change of temperature also contributing in affecting the solubility. The conductivity probe helps indicated the turbid point in the solution.
Use Ethernet and Enable SSH:
Use Ethernet to connect the computer and the Raspberry Pi together in a local area network.
Final Black Box Design:
The dimensions of the acrylic black box are 524.45 mm x 277.21 mm x 194.31 mm (20.65 in x 10.61 in x 7.65 in). The box needed to be large enough to house the IKA RCT 5 Digital magnetic stirrer, the sensor mount, and all of the circuitry for this experiment. Acrylic glue, epoxy cement, was used to glue the pieces together and RTV sealant was used to seal the seams of where the edges of pieces met together.
Solid Delivery System:
Using a stepper motor to open the door to the salt container allows for large scale preparation at the beginning and less time washing a block of material. The motor rotates and the plate at the end of the threaded rod laterally moves to let solid solute into the box.
Circuit:
Circuit for RGB color sensors, the stepper motor and its driver, and the temperature sensor. The stepper motor is powered by the battery. Temperature sensor connects to the 4.7k Ohm resistor. The temperature sensor (DS18B20 type) here is for showing how the temperature sensor connects to the T-cobbler in the circuit, the waterproof DS18B20 temperature sensor in the experiment looks different but connects to the T-cobbler in the same way. The Adafruit Pi T-Cobbler Plus allows the sensors to connect to the GPIO pins of the Raspberry Pi easier.
The team designed the PCB instead of using solderless breadboard. The top side of the PCB is shown in the left figure, and the bottom side is shown in the right figure.
Final_Product_Video.mp4Final Product Video
Final Product Video
Introduction on how to use each part of the system.
Result and Performance:
The first version of the system has not met the performance requirements since it is the “prototype.” However, the team is able to understand and foresee how the actual version will perform in the experiment. The team utilized this first version to do the experiment with the solution of sodium sulfate (Na2SO4) and water. Certain calibration is needed for comparing the difference between the data output of RGB color sensors with a tolerance. Temperature sensor records the slightly change of temperature in the experiment.
In the final version of the system, the results of the experiment include experiment setup data (information input by the users), temperature data, conductivity data, RGB sensor data, solvent data that are added into the beaker by the pump, and the operation time for each sensor over the duration of the experiment. The final product aims to reduce the human interaction to the least time. The final data are exported into an Excel file, and an email with the Excel file is sent in the end of the experiment to the users. If the experiment fails because the volume of the solution is greater than 80% of the beaker's capacity, an alert email with the experiment data is also sent to the users.
The RGB values detected by the RGB color sensors without calibration (left) and with calibration (right).
Temperature vs. Time
Temperature vs. Time
Temperature data for water and salt solution in Fahrenheit are collected by the DS18B20 temperature sensor and exported to the Excel file. The temperature sensor collects the data of the solution every 0.5 second (this time rate can be adjusted in the Python code). MATLAB is used to import Excel file and plotted the data. Using Excel's graph function can also produce the graph, which is convenient for users who do not use MATLAB.
Conductivity vs. Time
Conductivity vs. Time
Temperature data are collected in micro Siemen every 0.5 second(this time rate can be adjusted in the Arduino code). MATLAB is used to plot the data.
Conversion (Pump Data)
Conversion (Pump Data)
Flow rate(ml/s) = 0.04RPM
Volume (mL) = 2.4Revolutions
Example (prototype) of how the data from each sensors and the pump exported to the Excel file. More data are exported to the Excel file in the actual experiment.
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