device 502 analog to digital a d converter 504 for converting analog signals to digital signals a computer 514 for managing entire elements of the system 500 an amplifier 506 a waveform generator 510 for converting digital signals into the analog lamb wave signals and a relay switch array module 512 configured to switch connections between the device 502 and the computer 514 in general more than one device 502 may be connected to the relay switch 512 the device 502 may be one of the sensors described in fig1 a 2d and fig4 a d that may include a piezoelectric device for generating lamb waves 517 and receiving lamb waves generated by other devices to generate lamb waves 517 a waveform generator 510 may receive the digital signals of the excitation waveforms from computer 514 more specifically an analog output card included in the computer 514 through the relay switch array module 512 in one embodiment the waveform generator 510 may be an analog output card the relay switch array module 512 may be a conventional plug in relay board as a u201c cross talks u201d linker between the actuators and sensors the relay switches included in the relay switch array module 512 may be coordinated by the microprocessor of the computer 514 to select each relay switch in a specific sequencing order in one embodiment analog signals generated by the waveform generator 510 may be sent to other actuator s through a branching electric wire 515 the device 502 may function.