In view of food scandals in Taiwan which have hurt many people's health, we use Synthetic Biology to create a low cost recycled oil detector. This detector can retrench the cost and the time of testing oil. We hope the public can ensure the food safety together. The substance we detect are Benzo[a]pyrene, Cadmium, Copper, Mercury, Lead, etc. All of them are the substance often being detected in the recycled oil. Also, we hope every levels of society can have more degree of understanding in synthetic biology. We sought for the opinions from various aspect and popularized the concept of biosensor. Let the public know everyone all have the right to ensure the food safety and contribute to the society!