Patents are many times causing sensitive feelings. However, the sensor area has been very quiet about tough patent fightings. Sure there are some cases such StMicro vs. Invensense and some other.
The main message here is that most sensors and sensor use cases are free as the most of them have been published already 1980 and early 1990 when the previous sensing boom was going with the first entrance of mobile phones, wearables, context awareness on those years. Also many sensors used in mobile devices nowadays have they predecessors in automotive or industrial applications or studied and presented in the futuristic or forward looking research projects of many universities over 20 years ago.
MobileDeviceSensor.com will do patent reviews of sensor topics, and, of course, follow latest interesting publications and patents granted. The main point is to find out the core of innovation, explain, evaluate and give lessons learn about them. That is a important aspect to utilize them for improving technology and applications even further.