Daphnia Heart Toxicity Screening with a Smartphone

ISEF Category: Biomedical Engineering

Subcategory: Cell and Tissue Engineering  ·  Difficulty: Intermediate  ·  Setup: School Lab  ·  Time: 1 to 2 Months

The Hook

A tiny water flea can react to chemicals in ways that are easy to see under a microscope. That makes Daphnia magna a simple stand-in for early toxicity screening. You can track heart rate changes with a phone and a cheap microscope setup. This gives you a real bioengineering project without a full lab.

What Is It?

Daphnia magna are tiny freshwater crustaceans. Their transparent bodies let you watch the heart pump in real time. That makes them useful as a simple living sensor for stress, toxicity, and drug effects. If a chemical changes heart rate, you can measure that change and compare compounds.

Think of the Daphnia heart like a tiny metronome. When a compound affects the animal, the beat can speed up, slow down, or become irregular. You can test common household compounds such as caffeine, nicotine vape liquid, or taurine-containing energy drinks, then compare the pattern of response across doses. A smartphone microscope helps you record the heart and count beats from video instead of trying to guess by eye.

Why This Is a Good Topic

This project works well because the response is visible, measurable, and easy to turn into data. You can change one variable at a time, such as compound type or dose, and track heart rate as your outcome. The topic connects to real questions in toxicology, product safety, and screening for heart effects. You can also compare your findings with published mammalian-cardiomyocyte EC50 values, which adds depth without needing a university lab.

Research Questions

• How does caffeine concentration change Daphnia magna heart rate?
• How does nicotine vape liquid concentration change Daphnia magna heart rate?
• How does taurine-containing energy drink concentration change Daphnia magna heart rate?
• Does heart rate recover after Daphnia magna are moved back to clean water?
• To what extent do different household compounds produce different dose-response curves in Daphnia magna?
• Which compound causes the largest change in heart rate at the same relative dose?
• How does smartphone-video heart rate counting compare with manual microscope counting?

Basic Materials

• Daphnia magna starter culture
• Small glass or plastic container for culture water
• Spring or dechlorinated tap water
• Compound microscope or low-power biology microscope
• Smartphone with video recording
• Smartphone microscope adapter or clip-on macro lens
• Disposable transfer pipettes
• Small petri dishes or cavity slides
• Digital timer
• Labels and waterproof marker
• Household test compounds with known ingredient labels
• Safety gloves and safety glasses
• Notebook or spreadsheet for data tables.

Advanced Materials

• Daphnia magna culture and feed
• Compound microscope with camera port
• Smartphone microscope adapter or microscope camera
• Microfluidic slide or custom chamber for controlled exposure
• Calibrated pipettes
• Temperature probe
• Dissolved oxygen meter
• pH meter
• Water hardness test kit
• Controlled-light imaging setup
• ImageJ-compatible video files
• Reference cardiotoxicity data from published studies
• Statistical analysis software.

Software & Tools

• ImageJ: Measures frame-by-frame heart rate from microscope video and helps you count beats consistently.
• Google Sheets: Organizes dose-response data and calculates averages, standard deviations, and graphs.
• Python: Fits dose-response curves and compares response patterns across compounds.
• PubMed: Finds review articles and primary papers on Daphnia toxicity and cardiotoxicity.
• NIH PubChem: Checks chemical identity, structure, and safety context for the compounds you test.

Experiment Steps

1. Define one biological endpoint, such as heart rate, beat regularity, or recovery time, so your project stays focused.
2. Choose a small set of compounds and doses that let you compare one chemical class at a time.
3. Plan a standardized imaging setup so every Daphnia is filmed under the same lighting, magnification, and background.
4. Build a measurement method that turns video into a repeatable heart-rate value.
5. Design controls that separate chemical effects from handling stress, temperature shifts, and water-quality changes.
6. Plan your analysis before you collect data, including dose-response plots, replicate counts, and a way to compare your results with published EC50 values.

Common Pitfalls

• Using inconsistent lighting or focus during video capture, which makes heart beats hard to count.
• Comparing Daphnia of different sizes or ages without controlling for life stage, which adds extra biological noise.
• Leaving compound residue in the chamber between trials, which contaminates later measurements.
• Measuring heart rate right after rough handling, which mixes stress effects with chemical effects.
• Treating drink labels as exact chemistry, which can hide the fact that energy drinks contain multiple active ingredients.

What Makes This Competitive

A strong version of this project does more than show that a chemical changes heart rate. You can test several doses, fit a dose-response curve, and compare response patterns across compounds. You can also add recovery measurements, repeatability checks, or a comparison between manual counting and smartphone analysis. If you connect your results to published toxicity data and explain where your surrogate agrees or disagrees, your project becomes much stronger.

Project Variations

• Test caffeine, taurine, and nicotine separately to compare stimulant effects across chemical classes.
• Compare canned energy drinks against pure ingredient solutions to see whether the full product behaves differently from a single compound.
• Use video analysis versus manual counting to study whether smartphone-based heart-rate detection changes measurement precision.

Learn More

• NCBI Bookshelf: Search for free textbook chapters on toxicology, dose-response curves, and basic pharmacology.
• PubMed: Search for review articles on Daphnia magna cardiotoxicity and aquatic toxicology.
• NIH PubChem: Look up each compound’s structure, synonyms, and safety information.
• NOAA Aquatic Toxicology Resources: Find background on how chemicals affect aquatic organisms.
• ImageJ documentation: Learn how to measure frame-by-frame changes from microscope videos.