Dual sensing occupancy sensors?

Other Hardware Sensors
1

Hi,

I am looking for a set of sensors that can provide 100 % correct human occupancy .
I initially thought PIR , but that is only 90% correct . so I was thinking can I use PIR+Ultrasonic together to detect 100 % correct results ?

I read some where LMV? sensor that checks weight of the occupant? but I was unable to find any sensor .

Please provide your inputs on what can be the best way ? Cost remain a factor for me . MICROWAVE SENSOR are costly here in India .

2

There are no sensors that detect "occupancy", and no sensors, of any type, that are 100% correct.

There are sensors that can measure weight, detect warm objects against a cooler background, movement, movement of warm objects, etc.

3

Thanks for your reply !! what are the weight sensors? any links? I have never seen them

4

strain gauges and force sensitive resistors