Hey, sorry for the delay in reply.
This sensor from Amazon. Less expensive can probably be found from China. If I were to build a bunch of heaters, I’d source it elsewhere. For now I’m going to give one of these a try in testing.
I have found this one that could be maybe placed under the mesh.
https://www.amazon.com/gp/product/B07YZVDWWB/ref=ox_sc_act_title_1?smid=A38CU2XC1RY0BO&psc=1
It would have to be to the side of the mesh not directly under it due to melted spice drops. I will order 1 or 2 to try them . I am also looking to open source my project for anyone interested.
Doesn't really apply to Frigate, though.
Although a passive IR detector can detect a person that is moving, once they settle down the IR sensor will no longer "see" them because it is triggered by a change in temperature; the person does continues to radiate IR energy when they're not moving but it is not changing.
I have found that a passive IR temperature sensor can be used to detect both the person entering into the field of detection, and remaining still because that type of sensor is outputting the average temperature of what it can "see", not triggering on a change.
Doing this of course takes additional automation, like a Arduino,Raspberry Pi, or even and ESP8266 to do the "detecting".
https://www.amazon.com/MLX90614ESF-Non-Contact-Infrared-Temperature-Arduino/dp/B07YZVDWWB
If you just want to experiment with something, you can try a low-cost infrared temperature sensor module like the MLX90614. With it's I2C interface it is easy to interface to an ESP8266 or Arduino for continuous readings.
The temperature it measures is an average of everything in it's 20 degree field of view, with a resolution of 0.02 C. The module also outputs the ambient temperature. I used one with an ESP8266 to measure the temperature of my water heater exhaust stack from a distance of about 16" and it works great.
You could mount it to the baby's crib so that it would look down on the baby's head, and track the temperature to see what it shows.
https://www.amazon.com/MLX90614ESF-Non-Contact-Infrared-Temperature-Arduino/dp/B07YZVDWWB
An infrared temperature module, connected to an ESP8266 Mini D1 module, mounted above the headboard, looking down, should be able to detect the increased temperature from a human being in the bed.
I'm using one of these IR modules connected to an ESP8266 Mini D1 module to measure the temperature of my gas water heater's exhaust pipe. The IR module and the ESP8266 module are the only two components used (plus a 5VDC phone charger). I used ESPHome to program the ESPHome module to send MQTT broadcasts of the temperature. There are other options instead of MQTT that could be used.
https://www.amazon.com/MLX90614ESF-Non-Contact-Infrared-Temperature-Arduino/dp/B07YZVDWWB
https://www.amazon.com/Internet-Development-NodeMcu-ESP8266-Compatible/dp/B07W8ZQY62
I would think that turning on the light when someone is in front of the sink would be a better idea than waiting until they turn on the faucet. So I have a suggestion:
I recently used a GY-906 MLX90614 non-contact IR temperature sensor, connected to a D1 Mini to measure the temperature of the exhaust stack on my gas water heater as a way to measure how long the heater is running.
I could have used a temperature probe but I wanted to see how the MLX90614 worked. It works great and sends the temperature as an MQTT value back to HA every 15 seconds. I don't care what the actual temperature is, I just want to know when the burner is going, and when it stops, so I have it mounted about two feet from the exhaust stack.
It works so good that I bought another sensor and am going to again wire it to a D1 Mini and mount it on top of my desktop PC monitor to detect when I am sitting in front of my PC so as to keep the room light on. Again, the actual temperature is not important, only an instant noticeable rise above room temperature.
So, to finally get to my point -- one of these sensors could be mounted behind your sink and detect when someone is standing in front of the sink. What makes it so simple is that it only requires 3 items: the GY-906 module, a D1 Mini, and a 5vdc microUSB power supply, and is programmed with ESPHome. No other support components are needed since the GY-906 module has an I2C interface.
https://www.amazon.com/MLX90614ESF-Non-Contact-Infrared-Temperature-Arduino/dp/B07YZVDWWB
Just yesterday I put together a little temperature sensor that only requires a Wemos D1 board and a MLX90614 IR temperature sensor. I want to use it to measure the amount of time my gas water heater is actually heating. Since I can't monitor the gas consumption it occurred to me that I can measure the relative temperature of the exhaust stack above the water heater.
I's already tested it with my handheld IR temp meter and it shows about 190 degrees F when the burner is on (I painted on some semi-flat automotive paint so the galvanized steel exhaust pipe would have decent IR emissivity.)
I just installed it yesterday afternoon and it is measuring the temperature of the stack. I have it mounted about 1 foot from the exhaust pipe. The ESP8166 sends out the temperature as MQTT broadcasts every 30 seconds (The MLX90614 also provides the ambient temperature).
https://www.amazon.com/MLX90614ESF-Non-Contact-Infrared-Temperature-Arduino/dp/B07YZVDWWB
The only items needed for this are the temp sensor, a Wemos D1 mini board, 4 connecting wires, and a micro USB power supply.
I got one of these little IR temperature sensors and am going to hook it up to an ESP32 to send MQTT data of the temperature. I want to monitor the burn time of a gas water heater so I think I can point it at the exhaust stack and the temperature will give me a good idea of when the burner is on.
https://www.amazon.com/MLX90614ESF-Non-Contact-Infrared-Temperature-Arduino/dp/B07YZVDWWB
Does he leave the induction cook top on with a pot or pan left on the "burner", or with nothing on it?
My thought is if a pot were left on it then the pot would heat up and you could possibly use a infrared sensor (not a PIR sensor) and a ESP8266 under the range hood aimed downward to detect the heat.
https://www.amazon.com/MLX90614ESF-Non-Contact-Infrared-Temperature-Arduino/dp/B07YZVDWWB
If the cook top is left turned-on but with nothing on it then it really shouldn't be a problem.