The CuMeter, What is it?

Introduction

The CuMeter was born from an idea during my social service, where I visited different communities in Puebla dedicated to pottery. In Mexico, pottery is glazed with lead oxide, which, when in prolonged contact with food, contaminates it and causes severe health issues, such as reduced IQ in young children. Currently, there are no regulations ensuring the sale of lead-free pottery products. Organizations like Pure Earth work to help artisans transition to lead-free pottery, but this process is often too expensive for pottery-making families.

This project was designed to support the quantitative detection of lead. However, detecting lead posed challenges due to its absorption wavelength. The sensors and LEDs operating within this wavelength range are not easily or economically accessible. As a result, I shifted the project's focus to another heavy metal, which is also present in various pottery products. This metals absorption wavelength falls within a spectrum that is more accessible for the required sensors, allowing the spectrophotometer to function effectively.

The CuMeter can measure the absorption of a prepared solution to detect the presence or absence of copper. It works by projecting a beam of light through each sample, which is moved by a CNC system to evaluate the necessary samples in the microplate. The OPT101 photodiode then measures the amount of light that passes through the sample, and the program calculates the ratio to finally display the results on an LCD.

Who has done what beforehand?

There are several projects focused on building a spectrophotometer from scratch. In fact, Seed Studio offers a module for conducting tests in the visible spectrum. However, all of these are custom designs and based on personal research. One video I could recommend that showcases another version of a spectrometer is this one.

These devices are quite expensive due to the components required to operate at such low wavelengths. Among the most costly components are:

• Light Source: High-quality lamps, such as xenon or deuterium, which provide stable and long-lasting illumination.
• Monochromator: A device that selects specific wavelengths, essential for the instrument's accuracy.
• Detectors: Sensors like photodiodes or photomultipliers that convert light into electrical signals with high sensitivity.

Leading Brand: Thermo Fisher Scientific

One of the leading brands in the field of spectrophotometers is Thermo Fisher Scientific. This company offers a wide range of UV-Vis spectrophotometers, such as the Evolution series, known for its reliable and versatile hardware as well as its user-friendly software.

Own design

What I designed in this project was the CNC structure, where I applied the principles from Week 10 to my project and used the motor movement system as a reference to build the microplate reader. The microplate reader evaluates one sample in each well of the microplate, requiring both horizontal and vertical movement to analyze samples across all rows of the microplate. In addition, I developed three PCBs, which integrate the connections for the NEMA17 motors, the LED that generates light, the OPT101 light sensor, and finally, display the results on an LCD. Moreover, I utilized 3D printing, laser cutting, and a router to construct the CNC structure.

BOM (BILL OF MATERIALS)

Component	Quantity	Approximate Cost (USD)	Link/Source
XIAO RP2040	2	6 usd	Seed Studio
Male Pin Headers (10-pin rows)	10	less than 2 usd	Fab Lab Ibero Puebla
LCD OLED	1	4 usd	Unit electronics
WIO Terminal	1	30 usd	I had it before the project
Soldering tin roll	1	11 usd	Steren
Double-sided tape	1	5 usd	Home depot
Copper boards for PCB etching	5	12 usd	Steren
A4988 Drivers	3	9 usd	Unit electronics
25V, 100uF Capacitors	2		Fab Lab Ibero Puebla
600nm Wavelength LED	1
Multimeter	1	10 usd	Fab Lab Ibero Puebla
Soldering station	1	32 usd	mercado libre
OPT101 Photodiode	1	22 usd	Mercado libre
NEMA Motors	3	13 USD	Unit Electronics
Microplate for sample evaluation	1	---	chemistry lab Ibero Puebla.
Copper sulfate solution	1	-	chemistry lab Ibero Puebla.
Red and black wire	2m	1usd	Steren
Toothed belt and pulley for NEMA 17 motor	1 kit	10 usd	Pulley Belt

Process used

• I used the electronic design process for the three PCBs I developed.
• Laser cutting was applied to certain parts of the CNC structure.
• 3D printing was utilized for joining the profiles and the base.
• A CNC router was used for machining.
• I also employed a chemical process to prepare the standard solution and reference solution for comparing the results obtained from my project.

What questions need to be answered?

Cost and Accessibility:

• How does the cost of this device compare to commercial spectrophotometers?
• Can the components be sourced easily to replicate or scale the project?

Impact and Applications:

• How effectively does the project address the issue of heavy metal contamination in pottery or other materials?
• Could the design be adapted for detecting other metals or substances?

Evaluation?

Real-World Testing

• Use real samples from pottery or other materials to detect copper content and assess practical application.
• Gather user feedback on ease of operation and accuracy of results.