Proposal

The device will be placed in the refrigerator unit rather than freezer unit. The sensor will start a timing if it receives sufficient light, no matter the light from outside or the light from fridge bulbs. Timing is cut if the light goes. If it lasts for 5 mins, it will trigger the beeper and beep for 10 seconds to remind us that we forget to close our fridge door. After completing these steps, I will try how to generate push up message send to my phone because sometimes we may already leave the kitchen and may not hear the noise.