MRI Guard

Your iPhone and Apple Watch are among your most important and most expensive companions — photos, chats, cards, half your life. And of all places, their most dangerous opponent waits at your workplace: an MRI scanner's magnet is never off. One step too far, and the field can wipe or damage your device — or tear it from your hand in an instant. We all know to be careful — and still it happens: an emergency, stress, one moment of distraction — and a device that holds so much is done for. Made for everyone who regularly deals with MRI: radiographers and MRI technologists, radiologists, other physicians and nurses in hospitals and practices, service engineers and researchers — and patients with a smartphone in their pocket. With MRI Guard, your devices protect themselves: the app reads the magnetic field around them and sounds a loud, unmistakable alarm as it climbs toward the danger zone — your moment to stop, check, and step back. MADE BY AN MRI PHYSICIST MRI Guard is built by Dr. David Grodzki — MR physicist, inventor of numerous MR patents, and multi-award-winning MR innovator, including the German Future Award for Technology and Innovation (Deutscher Zukunftspreis), presented by the German Federal President. It comes from someone who works with these magnetic fields first-hand and is deliberately careful about what the app claims. WHAT IT DOES • Live magnetic-field reading with a clear colour scale (green → red) • Adjustable alarm threshold — the default sits at the 0.5 mT / 5-gauss controlled-area line • Loud alarm and vibration when the field crosses your threshold • Keeps monitoring in the background, even with the screen locked • Optional Smart Alarm to reduce false alarms on a resting device • Choose your units: microtesla (µT), millitesla (mT) or gauss (G) • Pauses itself while charging (induction charging creates fields of its own) and resumes right after • Warns you when iOS Low Power Mode could delay monitoring • 10 languages STARTS BY ITSELF AT YOUR WORKPLACE (iPhone) Save your workplace once and MRI Guard arms itself the moment you arrive — hands-free, with a notification confirming it — and stops when you leave. Prefer to decide yourself? Switch to an arrival reminder and start with one tap instead. For reliable detection, allow 'Always' location with Precise Location on and keep Wi-Fi enabled. Shortcuts and Siri are supported too. APPLE WATCH (PREVIEW) Shows the field on your wrist and alarms while the app is on screen. watchOS does not allow measuring in the background; alarms from the iPhone reach the watch as notifications. FREE & FULL VERSION Measuring and the live display are free forever. The alarm, automations, Apple Watch and Shortcuts are part of the full version: try everything free for 3 days, then one single purchase — no subscription. PRIVATE BY DESIGN No account, no sign-in. Your saved locations stay on your device and are never uploaded. The app can share anonymous, aggregate usage statistics to help improve it — you can turn that off anytime in Settings. IMPORTANT — PLEASE READ MRI Guard is an awareness aid, not a certified safety device or medical instrument. The magnetic sensor in a phone or watch is uncalibrated and saturates at a few millitesla, so it cannot measure strong fields accurately and may not react in every situation. Never rely on it for safety-critical decisions. Always follow your site's MR safety rules and use approved measuring equipment. You are responsible for your own safety and your devices.