with semiconductor fabrication and packaging background, but struggling with switching path to sensor related field..
Analog integrated circuit design (basics)
MEMS
Mixed signal design basics also
Best way is to get into a company and/or team that does sensor integration and work from there. Also, if you understand the physics behind how sensors (optical/ultrasonic proximity, capacitive touch, etc) work that definitely helps. With the semiconductor background I’m quite sure you are aware of processes involved in development of MEMs based sensors.
Hey would it be OK if I DM you about interview prep?
Signal processing would be useful to know
Why do you want to do that? Please be aware the job market is much smaller in MEMS.
There are sensor integration roles at Apple. Many sensors aren’t MEMs based btw. 😉
Measurement and Instrumentation