What is CPD? Contact Potential Difference(CPD) refers to the electrical contact between two different metals and the electrical field that develops as a result of the differences in their Fermi energies. When two metals are placed in contact, the fermi energies of each will equilibrate by the flow of electrons from the metal with the lower Fermi energy to that of the higher.
Vibrating CPD sensor vs. Non Vibrating CPD sensor Vibrating CPD sensor refers to the vibration of one metal relative to the other in a parallel plate capacitor system. The vibration induces changes in the capacitance with time, and therefore a signal related with the surface profile. A CPD signal can also be generated by the translation of one surface past a reference sample. This translation make high speed scanning possible. Currently our research are focused on the Non-vibrating CPD systems.
Research Activities in CPD group
1 | PCB board scanning using nvCPD sensor. We use nvCPD sensor to see the fine lead traces on the printed circuit board, and now we can even see the tiny solder bumps on a silicon wafer. Usually these processes are done by much expensive optical systems.
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2 | In-situ monitoring nvCPD sensor on bearing. Our nvCPD sensor can be mounted on the bearing system to monitor its running.
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3 | Wear detection using nvCPD sensor in dry condition. Currently we are doing pin-on-disk test using our nvCPD sensor to try to relate our signal with the real wear process.
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