Executive Summary

The practice of synthesizing chemicals has relied on low technology equipment such as glass flasks and pipettes for decades. Flow chemistry was invented in order to modernize and advance the practice of synthesizing chemicals in terms of both safety and efficiency. Flow chemistry consists of pumping reagents into converging tubing in which the reagents mix to form a product. Flow chemistry exhibits a number of benefits over traditional laboratory methods. Firstly, the safety of reactions is greatly enhanced due to the minimization of time spent handling flask continuing chemicals. Additionally, reactions occur with smaller volumes of the readgest at a single time, therefore greatly reducing the potential for a major explosion or mishap. Secondly, reactions are more efficient due to the high surface area to volume ratio of the reagents involved. Increasing this ratio increases the kinetics of the reactions resulting in greater yield. A third advantage of flow systems is the greater level of control that can be obtained in reactions. Due to the incremental nature of the reactions, the chemical can be closely monitored and maintained at specific temperatures and pressures before entering the reaction [1]. Despite its multiple advantages, flow chemistry systems come with one large downside. Commercially available systems cost upwards of $20,000. This high price point makes it such that this technology is largely unavailable to academic laboratories and undergraduate students.

The sponsor of this project, Dr. Haim Weizman, a researcher and professor with the Department of Biochemistry and Chemistry, UCSD, hopes to make a chemistry flow system which is cost-effective and accessible to undergraduate laboratories. Various low-cost, DIY (Do It Yourself) flow chemistry systems have already been developed, however, these DIY systems have a number of shortcomings when it comes to ease of assembly and use. Dr. Weizman hopes to improve upon an existing DIY chemistry flow system by placing a greater emphasis on user-oriented design.

The specific flow system being improved upon is the Croatt Research Group’s DIY flow system [2]. This system is open access and can be manufactured using only a 3D printer and parts ordered from Amazon for a cost of around $150. The system consists of a carriage which pushes a syringe from within the chassis as can be seen in Figure 1. The motion of the carriage is actuated by a stepper motor which is controlled by an Arduino. The system is commanded by the user who inputs a string of commands to the Serial Monitor of the Arduino.

Issues with this system include non-intuitive user input commands to the Arduino, corrosion of the threaded rod, syringe holders specific to the syringe size as opposed to a single design which can accommodate multiple syringe sizes, and disorganized cable routing and inadequate protection of the electronics in the system. Additionally, this system requires the user to fill the syringe by hand before performing the experiment. This is potentially dangerous when working with hazardous chemicals and can lead to serious accidents in the laboratory.

This project implemented additions and modifications to the Croatt Research Group’s system in order to increase its functionality and usability. These additions include a Graphical User Interface (GUI), stainless steel hardware, a modular syringe holder, an electronics box and cable management strategy, as well as automated refill functionality. The GUI is intuitive and visually appealing as opposed to the previous commands entered into the Arduino’s Serial Monitor. This reduces the resistance encountered by new users to learning how to use the system and decreases the potential of incorrect inputs being entered. The stainless steel hardware replaces the previous steel hardware which became susceptible to corrosion and limited the functionality of the syringe pump. The electronics box protects the electronics from any potential spillages on the lab bench and increases the visual appeal of the system. Furthermore, the automatic refill option greatly enhances the safety of the flow system and decreases the amount of labor needed to operate the system. The system exhibits below 10% error in the flow rate when operated below its maximum limits. Additionally, the stoichiometric ratios between two pumps track closely with the desired ratio, exhibiting less than 6% error. The system can be operated for extended periods of time to complete reactions requiring volumes of product.