Abstract: A MEMS device may include: (i) a lower cavity, including a first island, formed within a first layer of the MEMS device; (ii) an upper cavity, including a second island, formed within a second layer of the MEMS device; (iii) a MEMS resonating element arranged in a device layer of the MEMS device and anchored via the first and second islands; (iv) a first set of electrodes for electrostatic actuation and sensing of the MEMS resonating element in an in-plane mode that is arranged in the device layer of the MEMS device; and (v) a second set of electrodes for electrostatic actuation and sensing of the MEMS resonating element in an out-of-plane mode that is electrically isolated from the first set of electrodes and located in the first or second layer of the MEMS device, and wherein the out-of-plane mode is a torsional mode or a saddle mode.

Abstract: pH-change sensors and related methods are disclosed. One such sensor may have a first ion-sensitive transistor-operational-transconductance-amplifier (the “first IOTA”) and a second ion-sensitive transistor-operational-transconductance-amplifier (the “second IOTA”). Each IOTA may have an ion-sensitive transistor, a load transistor, and an output. In each IOTA, the drain region of the ion-sensitive transistor may be connected to the drain region of the load transistor. A differential sensor may be connected to the IOTAs, and an output from the differential sensor may indicate a voltage difference between the IOTA outputs. The output from the differential sensor may be used to provide an indication of a change in pH.