In the mid-90's I briefly worked for a company who built and installed security systems using this principle, and it looks like they are still going: https://ww

In the mid-90's I briefly worked for a company who built and installed security systems using this principle, and it looks like they are still going: https://www.remsdaq.com/solutions/integrated-security-systems/perimeter-intrusion-detection-systems-pids/sabreline-buried-pressure-sensors/ https://www.remsdaq.com/solutions/integrated-security-system...