DIY Spectrophotometer

Overview

The Spectrophotometer kit is a low-cost activity and instrument that aims to remedy many of the problems high schools are encountering with integrating hands-on STEM learning into their more advanced classes. Research shows that 40% of students are visual learners, and 30-40% are tactile/kinesthetic learners. This represents a majority of kids who would benefit from increased hands-on learning.

goal

The goal of this project was to create a DIY spectrophotometer kit that is suitable for individual sale.The kit should be usable in a classroom from the development stage to accurate use in a lab setting.

Problem Identification

1) Price of Modern Instruments: Lab equipment that compliments the curriculum of high school classes is not affordable as a learning tool

2) Lack of Hands-on Instruction: Since this lab equipment is unattainable, high school students continue to learn the material without any practical use.

3) Lack of Collaboration Between Classes: Subjects in school feel very isolated. In the real world experts in different disciplines have to work together.

1. Adafruit ESP32 S3 - https://www.adafruit.com/product/5399
2. Adafruit 1.69" TFT Display - https://www.adafruit.com/product/5206
3. Adafruit 10 channel color sensor - https://www.adafruit.com/product/4698
4. Adafruit VCNL4040 Proximity and Lux Sensor - https://www.adafruit.com/product/4161
5. Adafruit 1x4 neokey - https://www.adafruit.com/product/4980
6. Adafruit EYESPI Breakout Board - https://www.adafruit.com/product/5613
7. LED Backlight Module - https://www.adafruit.com/product/1626
8. ribbon cable breakout
9. 4 cherry mx blue switches
10. small breadboard
11. wires
12. PLA
13. balsa wood

create the base in CAD and 3d print it. It should have a section to place the breadboard, test tube, light, proximity sensor, and color sensor.

Create the top in CAD and 3d print it. It should have a section to place the display and buttons.

Either cut the balsa wood with an X-ACTO knife or design the sides in CAD and cut it on a Cricut machine. Make sure to cut out a hole in the back for the usb-c port.

CAD files are available upon request.

If you are using all the sensors with Stemma QT it is as simple as connected them together with stemma cables. You will also have to wire the EYESPI Breakout Board to the Feather, using the wiring schematics on the Adafruit website to connect the ribbon cable to the display.

Reference the fritzing diagram shown earlier.

I have attached two snippets of my code that go over the most important parts. The basic function of this program is setting up the buttons as green, blue, and two white. When you press the green button it turns on the light and takes a reading of the color coming through the test tube. Each of these 10 channels (8 excluding white and lux) is then displayed on the display using a bar graph. The blue button will take a "blank" sample so you can ignore the base color of whatever sample you are testing. The two white buttons adjust the gain of the sensor (right is up, left is down).

code is available upon request.

Place the sidewalls into their channels on the base and epoxy them to one another and in the channel. Epoxy the lid lip onto the lid. Wait to epoxy down the lid to the box until all the sensors are in place.

Place the board and sensors in their proper slots and secure with tape or epoxy.

1. Price of Modern Instruments The most expensive parts of modern spectrophotometers are the color gradient, the photon detector, and the processing system. I was able to lower this price by bypassing the color gradient-detector system and instead use a single 10 band color sensor. This means it is not detecting the entire spectrum of light but rather a few wavelengths. From this data it can estimate an absorbance curve. While it is not as accurate, it still demonstrates the concept of spectroscopy and is accurate enough to facilitate lab work.
2. Lack of Hands on Instruction in High Schools Every step of the kit involves hands-on work. From the building, to the coding, to the testing, and to its use in labs students will be engaged with the spectrophotometer.Additionally, after creating a product with your own hands it gives each person more value for the science they are conducting. After spending multiple class periods putting the spectrophotometer together kids will be more motivated to conduct the labs with it. A desire to learn is the number 1quality related to academic success.
3. Lack of Collaboration Between Classes The spectrophotometer kit utilizes skills taught in CAD, computer science, chemistry, and environmental science classes. The instructions make sit possible for one class to put it together and use it alone.However, ideally it would be a collaborative effort between classes that encourages students to talk to one another and problem solve in an academic setting that requires them to utilize the knowledge of their peers. Many group assignments are left to one person doing all the work, but this kit that would be impossible.

The DIY Spectrophotometer kit aims to increase the number of hands-on activities in high school classrooms, reduce the cost of modern-day lab equipment, and increase collaboration between different subjects. This product is the first of its kind and will be competing in the American public school market which spends $857.2 billion a year and eventually the global secondary education system.

The kit, when put together, can give estimated transmittance and absorbance data which can then be displayed on the LED display. It is also able to “blank” a control substance or buffer solution in a substance the same way other spectrophotometer scan.

Putting the kit together is simple and comprehensive at an advanced high school level. It is successfully able to execute pertinent labs to advanced chemistry classes like AP Chemistry.This was tested by giving the kit to a few of my high school friends, currently enrolled in high school chemistry, who were able to put it together and get a transmittance reading from a test tube.

Currently, the kit costs $80 to make, however, the cost can bebrought down substantially by printing my own printed circuitboards in the future.