Because unsafe cooking oil in Taiwan has hurt many people's health, we use Synthetic Biology to create a low cost recycled oil detector. This detector can retrench the cost and time of oil testing. We hope the public can monitor and ensure food safety together. The substance we detect are Benzo[a]pyrene, Cadmium, Copper, Mercury, Lead, etc, which are the substances commonly detected in recycled oil. Also, we hope every levels of society can have better understanding in synthetic biology. We sought the opinions from various aspects and popularized the concept of biosensor. Let the public know everyone has the right to ensure food safety and the opportunity to contribute to the society!