  Wireless sensors based on micro-machined tunable resonators are important in
a variety of applications, ranging from medical diagnosis to industrial and
environmental monitoring.The sensitivity of these devices is, however, often
limited by their low quality (Q) factor.Here, we introduce the concept of
isospectral party time reciprocal scaling (PTX) symmetry and show that it can
be used to build a new family of radiofrequency wireless microsensors
exhibiting ultrasensitive responses and ultrahigh resolution, which are well
beyond the limitations of conventional passive sensors. We show theoretically,
and demonstrate experimentally using microelectromechanical based wireless
pressure sensors, that PTXsymmetric electronic systems share the same
eigenfrequencies as their parity time (PT)-symmetric counterparts, but
crucially have different circuit profiles and eigenmodes. This simplifies the
electronic circuit design and enables further enhancements to the extrinsic Q
factor of the sensors.
