Overview

During the early stages of this year’s iGEM competition, our team was originally planning to experiment with several microRNA biomarkers that were implicated in the biological stress response by Wiegand et. al. However, due to time limitations, we were not able to achieve this goal in the lab. However, we realized that thermocyclers used to amplify microRNAs are extremely expensive, ranging from several thousand all the way up to fifteen thousand dollars. For our hardware, our team wanted to propose a low-cost method of amplifying microRNA sequences. Our heating mechanism consisted of four wirewound resistors relayed by a Solid-State Relay and powered by a 9-volt battery. Our cooling mechanism consisted of an aluminum heat sink and four cooling fans. We used an Arduino Uno board to control the hardware’s logic, and an ESP8266 WiFi module to allow our device to interact wirelessly with other devices or with the Cloud.

Our device, while novel, does have several limitations. For one, commercially-sold PCR machines go through rigorous testing to ensure that they can warm and cool reagents to specific temperatures in a short amount of time. The thermocycler we designed would likely be unable to compete with on-the-market designs in terms of efficiency, but it does serve as a model for future development. We believe that by making thermocyclers more cost-efficient, wait times for diagnostic tools can become shorter, as more diagnostics facilities will be able to afford PCR machines, shortening the shipping distance from diagnostic kit to the lab.

Purpose

This low-cost PCR machine was built by the 2023 EmpireSpit team for the International Genetically Engineered Machine (iGEM) competition. This guide can help future teams or external researchers with designing their own low-cost machine. While traditional thermocyclers can cost thousands of dollars, this device catalyzes a low-cost version of PCR with affordable materials. Electronic parts were ordered from online vendors, and 3D printing was made possible with the help of the Biotech Commons at the University of Pennsylvania.

Guide to Building a Low-Cost PCR Machine

Materials

• 3D Printer
• Arduino Uno or a compatible Uno board
• ESP8266 Wi-Fi Module
• 9V battery holder for Arduino connection
• 9V battery
• Solid State Relay DC to AC 25A
• 4 100 W 50 ohm wirewound resistors
• 4 Cooling fans, 40 x 40 x 10 mm
• Aluminum heat sink, 80 x 80 x 27 mm
• Thermal conductive glue

Check out our own guide to building a Low-Cost PCR Machine