About TremorCheck

A progressive neurodegenerative disorder caused by the gradual loss of dopamine-producing neurons in the substantia nigra region of the brain. It primarily affects movement control and typically presents after age 60, though early-onset forms exist in younger adults.

An estimated 10 million people worldwide live with Parkinson's disease. Early detection is critical — starting treatment earlier can significantly improve quality of life.

• Parkinson's tremor: 4–6 Hz — at rest, rhythmic, typically unilateral onset

• Essential tremor: 6–12 Hz — appears with action or posture holding

• Physiological tremor: <3 Hz or irregular — completely normal in healthy people

• Drug-induced tremor: Variable — can mimic Parkinson's or essential tremor

Step 1 — Calibration: Measures background sensor noise for 5 seconds while the phone is still. This establishes your personal baseline RMS value.

Step 2 — Measurement: Records accelerometer data for 30 seconds while you hold the phone upright in your hand.

Step 3 — FFT Analysis: Converts raw time-domain data into a frequency spectrum using the Cooley–Tukey Fast Fourier Transform with a Hann window to minimize spectral leakage.

Step 4 — Tremor Score: A weighted composite of three factors: dominant frequency in the Parkinson range (45% weight), amplitude above your baseline (35%), and spectral concentration / clarity (20%). All three must be simultaneously elevated to produce a high score — this multiplicative design prevents false positives from random movement.

✅ Best experience: Safari on iOS, Chrome on Android

⚠ Brave browser: Brave blocks device sensors by default. To fix: tap the Shield icon (🦁) in the address bar → disable "Block device sensors" → reload the page.

iOS Safari permission: When you tap Calibrate or Start, a permission prompt appears. If you previously denied it: Settings → Safari → Motion & Orientation Access → enable.

HTTPS required: The DeviceMotion API only works on secure (HTTPS) connections. Make sure the URL starts with https://.

Consult a neurologist if you notice: a rhythmic tremor in your resting hand (especially one-sided), slowing of movement, muscle stiffness, or balance problems — particularly if symptoms have persisted for several weeks. Early detection and treatment significantly improves outcomes.

TremorCheck is developed as an accessible early screening tool, designed to help individuals monitor potential tremor symptoms in the period between neurologist visits. This application represents a project task created by Viktorija Andonova, a student at "Kole Nehtenin" School. The goal of the project is to contribute to greater accessibility and awareness of neurological screening.

Important: The tool does not represent a substitute for professional medical evaluation and should always be used in combination with appropriate medical care.