The invention is a capacitively coupled probe which can be used for non-contact acquisition of both analog and digital signals. The probe includes a shielded probe tip, a probe body which is mechanically coupled to the probe tip, and an amplifier circuit disposed within the probe body. The amplifier...http://www.google.se/patents/US5274336?utm_source=gb-gplus-sharePatent US5274336 - Capacitively-coupled test probe
