Description

Identified problem

Serial dilution is a stepwise series of dilutions used to reduce the concentration of chemicals in the lab to a more usable concentration. It is a commonly employed technique and is used to prepare so many different solutions: standard solutions, buffers, solutions of extremely low concentration, and whatnot.

Due to the repetitive nature of manually transferring and mixing the solutions, as well as the use of numerous beakers/tubes, the whole process can become quite tiresome to keep track of and complete, and this brings about significant room for error. Furthermore, if a large number of chemicals are involved, the entire process can be extremely time consuming and take up to hours to complete.

Proposed solution

As a result, our team decided to design a device that can automate the process of serial dilution. This will not only help avoid silly mistakes such as mixing up test tubes and creating unnoticed air bubbles in the pipette, but it will also allow the user to carry out other tasks simultaneously or even run the dilution process overnight, allowing them to start the experiment immediately the next day with minimal preparation work required.  

For ease of calculation, we will be using 1 ml pipettes and 25 ml beakers, such that it can attempt to mirror the 1:25 ratio typically employed in chemistry labs when using the 250 ml volumetric flask. However, the pipette can also be programmed to move back and forth to dispense multiple aliquots, if a larger volume of solution is required. The solutions will also be stirred using a magnetic stirrer, ensuring that a homogenous solution is obtained which will further circumvent errors posed due to improper or inadequate mixing.

Vision

Our project aims to streamline the process of serial dilution by creating an efficient, precise and automated serial dilution system. This device enhances reproducibility in the lab, and allows lab users to save valuable time. By automating the repetitive and tedious steps of serial dilution, this machine frees users from manual preparation, allowing them to focus on other steps of the experimentation process.  Ultimately, we seek to create a user-friendly device that can integrate into the various experimental setups, supporting a wide range of applications while ensuring accuracy and reliability.

Overall, we aim to achieve a machine that is able to produce solutions of decreasing concentrations with a consistent ratio with:

• Homogeneity

1. 1. 1. Magnetic stirring mechanism that stirs the solution in tandem with the dilution process
      2. By the time the pipette takes an aliquot of a previously diluted solution (A) to prepare the next dilution (B), A is already mixed thoroughly to ensure maximum accuracy when preparing B.  

• Limited Cross Contamination

1. 1. 1. Two stepper motors → one to help suck the liquid into the pipette tip, and the other to help eject the pipette tips in between subsequent dilutions 
      2. Ensures that residual solution from one dilution does not mix with another dilution, and throw off accuracy  

• Autonomous Functionality 

1. 1. 1. Limited intervention of humans during the dilution process, such that they are free to focus on other lab-related activities while the dilution process is being carried out → saves time overall
      2. We hence do not have to speed up the actual machine function and compromise accuracy, but instead introduce efficiency by ensuring that the user can take their eye off the machine and focus on other tasks