A method is provided for measuring the insertion distance of an intravaginal article within a human vaginal cavity. The device further includes a p-electrode contacting to the p-type semiconductor layer, and including a first conductive oxide layer having an oxygen content lower than 40 atomic % and a second conductive oxide layer contacting to the first conductive oxide layer and having a higher oxygen content than the oxygen content of the first conductive oxide layer. The control apparatus comprises a sense amplifier, a differential circuit, and a control circuit. The second remote unit comprises a downlink antenna port and a second uplink antenna port.