Smart Geiger is a sub-miniature sensor of cheap price which can detect radioactivity easily and conveniently by connecting to the earphone jack of a smart phone. It indicated radiation coming out from a radioactive substance in dose-rate figure (uSv/h) and informs even by sound, using semiconductor sensor. The measurement error is approx. within 30% because there are many different kinds of smart-phones in the market. Therefore, you may leave the exact measurement of radiation dose to experts, and you can carry out preliminary simple measurement by inserting Smart Geiger into the smart-phone. Smart Geiger is manufactured by R&D specialized company, FT Lab with a sense of mission, which has obtained 3 New Technology Certifications during the last 14 years of its R&D career.