Systems and methods for activating a token to enable a user to enter a transaction based on information received from a recovery key and a passcode are described herein. A bridge circuit includes a set of strain gauges bonded to the coupling pin portion. The receiving element is structured so as to be movable together with the movable blade as the movable blade moves. One embodiment of the invention is a transconductance enhancement circuit that improves transconductance and input impedance relative to the prior art. For example they are used to control army worm, diamond backmoth and aphid, and culex mosquito.