Identifing best choice for temperature sensor

Hello everyone!

I’m currently working on a project for which I’m now building an activation system.

What I want to do is to turn on my system placing hands on a surface and waiting the temperature on that surface goes up due to the heat released by the hands;


Here’s a terrible (and maybe unnecessary) sketch

this means the hands won’t be in direct contact with the sensor that is likely to be under that surface (I suppose a metal surface is better?).

The way I thought of doing it is to detect heat change and not just a specific temperature. The metal plate should maybe activate if it increases X degrees in temperature over a minute or so but not if the room temperature changes throughout the day.

Due to my inexperience, I don’t know which temperature sensor is the best for this job.
“Best” here means both that is able to do this task, both easy use but also cheap.

the sensors I’ve been looking at for now are these:

DS18B20+ TO-92

DHT11

Si7021

One last note: I don’t care about this activation system to be fast. Actually it’s quite the opposite, I’ll code it in a way that takes a certain time. I need the interaction to be slow.

If you can help me in chosing the best one I’ll appreciate a lot :slight_smile:

Thanks in advance!

Among the candidates I like the DS18B20. Drill a clearance hole in the side of your plate and insert the sensor. Using heat shrink on the leads solder 3 leads to the sensor. Place some thermal compound in the hold, insert the sensor and epoxy over the hole. Sensor response time will depend on the thermal conductivity of the plate material.

Ron

Ron_Blain:
Among the candidates I like the DS18B20. Drill a clearance hole in the side of your plate and insert the sensor. Using heat shrink on the leads solder 3 leads to the sensor. Place some thermal compound in the hold, insert the sensor and epoxy over the hole. Sensor response time will depend on the thermal conductivity of the plate material.

Ron

Thanks Ron, I really appreciate the tips! Since, as I've wrote above, I'm very inexperience, these kind of suggestions are gold to me.

Do you think I can do the same without drilling the hole on the place but placing the sensor underneath? I'd like to mantain the surface of the metal plate untouched.

Also, could connecting 2 of these sensors in parallel be a better way to "map" the metal plate? Or it would be just overachieving?

Thanks for your answer

With something like this I really don't see where two (or more) sensors would be beneficial. You would end up reading the sensors and likely taking an average or let them have a race and see who gets to your set point first. :slight_smile:

No, you can mount the sensor to the bottom of the plate. How well or how fast the plate responds is just a matter of the thermal conductivity abilities of the plate. Also, how the DS18B20 (or any sensor) is mounted. Under the plate is just fine. The plate can be any alloy you choose which has good thermal conduction.

Ron

Ron_Blain:
With something like this I really don’t see where two (or more) sensors would be beneficial. You would end up reading the sensors and likely taking an average or let them have a race and see who gets to your set point first. :slight_smile:

No, you can mount the sensor to the bottom of the plate. How well or how fast the plate responds is just a matter of the thermal conductivity abilities of the plate. Also, how the DS18B20 (or any sensor) is mounted. Under the plate is just fine. The plate can be any alloy you choose which has good thermal conduction.

Ron

Thanks again:)