Arduino Heavy Metal Soil Testing Project
ISEF Category: Chemistry
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Subcategory: Analytical Chemistry · Difficulty: Advanced · Setup: School Lab · Time: Full Year
The Hook
Lead in soil can end up in garden produce, dust, and runoff. A cheap sensor that spots it before a lab report arrives could matter a lot. You can build one with parts that fit in your hand. Then you can test whether it agrees with EPA reference data.
What Is It?
This project is about measuring tiny amounts of metal ions in soil water, called leachate. Think of soil like a sponge. When water moves through it, it can pull out dissolved metals, and those metals can then be detected in a liquid sample.
Your main tool is anodic stripping voltammetry, a method that first traps metal ions on an electrode, then measures how they release during a voltage scan. The signal acts like a fingerprint for metals such as lead and copper. An Arduino plus an LMP91000 potentiostat board can control and read that signal, so you can build a low-cost meter instead of using a full lab instrument.
The hard part is not just getting a signal. You also need to compare your readings with a trusted reference, like ICP-MS values from EPA open datasets. That lets you ask whether your DIY sensor tracks real contamination levels or just produces noise.
Why This Is a Good Topic
This is a strong science fair topic because it mixes chemistry, sensors, and data validation. You can change one variable at a time, like electrode type, sample source, or pre-treatment method, and measure how the signal changes. The project also connects to real problems, like lead exposure, garden safety, and water quality. You can learn how analytical methods work, how calibration helps, and how to compare your results to a gold-standard dataset.
Research Questions
- How does soil type affect the anodic-stripping signal for lead in leachate?
- What is the effect of electrode material on the sensitivity of a DIY voltammeter for copper detection?
- Does filtering soil leachate improve agreement between Arduino readings and ICP-MS reference values?
- To what extent do pH changes in leachate shift the measured peak current for lead?
- Which calibration model best converts voltammetry signal into metal concentration for low-cost hardware?
- How does the DIY sensor performance change when testing soil from contaminated and non-contaminated sites?
Basic Materials
- Arduino-compatible microcontroller board.
- LMP91000 potentiostat board.
- Working, reference, and counter electrode set suitable for stripping voltammetry.
- Soil samples from at least two locations.
- Plastic or glass beakers for leachate preparation.
- Disposable pipettes or transfer pipettes.
- Digital kitchen scale with 0.1 g accuracy.
- pH strips or a pH meter.
- Distilled or deionized water.
- Coffee filters or lab filter paper.
- Notebook or spreadsheet for recording measurements.
Advanced Materials
- Arduino-compatible microcontroller board.
- LMP91000 potentiostat board.
- Three-electrode setup with interchangeable working electrodes, including carbon, gold, or bismuth-coated surfaces.
- Benchtop pH meter.
- Analytical balance.
- Lab glassware for controlled leaching and dilution.
- Certified metal standards for lead and copper.
- ICP-MS reference dataset from EPA open data.
- Centrifuge or vacuum filtration setup for cleaner leachate preparation.
- Shielded cables and an enclosure to reduce electrical noise.
Software & Tools
- Arduino IDE: Uploads control code and logs voltammetry signals from the board.
- Excel or Google Sheets: Organizes calibration data, plots signal curves, and fits simple models.
- Python: Runs regression, error analysis, and comparison plots for sensor validation.
- ImageJ: Helps if you photograph electrode surfaces or test strips during method checks.
- RStudio: Supports statistics, residual plots, and agreement analysis with reference data.
Experiment Steps
- Define the metal, sample types, and comparison data you will use first.
- Choose one electrode setup and one signal-processing approach to standardize before testing samples.
- Build a calibration plan that turns raw voltammetry peaks into concentration estimates.
- Design controls that separate true metal signal from soil color, pH, and sediment interference.
- Match your DIY readings to EPA reference values and decide how you will judge agreement.
- Refine the protocol based on the biggest source of error, then repeat the full comparison.
Common Pitfalls
- Using soil extracts that are too cloudy, which hides the stripping peak and makes readings unstable.
- Skipping a calibration curve, which leaves you with signal values that cannot become concentrations.
- Changing electrode surfaces between trials, which makes repeatability look worse than it really is.
- Ignoring pH and ionic strength, which can shift the metal signal even when concentration stays the same.
- Comparing your data to the wrong EPA reference sample, which breaks the validation step.
What Makes This Competitive
A strong version of this project goes beyond just making a signal appear. You compare your DIY sensor to a real reference set, quantify error, and explain where that error comes from. You also test more than one soil type or interference source, then use statistics to show when the method works and when it fails. That kind of careful validation matters much more than a flashy prototype.
Project Variations
- Test roadside soil, garden soil, and playground soil to see which matrix gives the cleanest lead signal.
- Compare carbon, gold, and bismuth working electrodes to find which one gives the best detection limit for copper.
- Use leachate from compost-amended soil versus sandy soil to study how organic matter changes sensor accuracy.
Learn More
- EPA Open Data Portal: Search for ICP-MS soil and water datasets to find reference metal measurements for validation.
- PubMed: Search for review articles on anodic stripping voltammetry and low-cost metal sensors.
- NIH PubChem: Look up lead, copper, and common electrode materials to review their chemistry and safety data.
- USGS Water Quality Data: Find background on metals in environmental samples and field sampling methods.
- MIT OpenCourseWare Chemistry: Use analytical chemistry lecture materials to review calibration, electrodes, and electrochemistry.