It’s interesting when we stumble upon cool discoveries by complete chance. Something similar happened to Neal Patwari of the University of Utah, when he realized that his breathing literally affected WiFi signal strengths. To make good on this theory he basically used 20 wireless units around a bed and then powered it down to one-thousandth of the original signal strength. This resulted in the WiFi signals going over and around the person’s body, with signal deviations measured in such precision that the person’s breathing rate could be monitored accurately.
Another experiment soon followed that using a similar technique, precise body movements can be monitored through a wall. These results obviously have a big implication on invisible security measures in banks and shopping malls where there’s no way to identify if a room is being monitored or not. Similarly hospitals can use this method to monitor a patient, albeit with other instruments to measure various stats as well.
How much privacy this can breach remains to be seen and depends entirely on how and why this technology is used.