Traditional Geiger counters are not portable nor cheap. But considering that many of us now use our smartphones everywhere we go, it does make sense to use these devices to get radiation readings where we go. The Pocket Geiger Type 4 happens to be a radiation detector for smartphones. The device measures the radiation contamination in an environment within 2 minutes, using photodiodes. The values are shown on your smartphone. It is portable and and not too expensive. Designed by Masashi Ogasawara.