A device for gathering data has first and second electrodes. The first electrode is coupled to a surface of interest, and the second electrode is coupled to “everything else” or “the air”. The first electrode is shielded from the second, and from most sources of parasitic capacitance, by a shield that is driven by an active driver that drives the shield to track, and ideally to match, the instantaneous potential of the electrode. The second electrode is likewise shielded in a similar way from most sources of parasitic capacitance. These shields likewise help to limit the extent to which RFI from the device electronics couples with either of the electrodes. In this way the sensing device achieves a markedly better signal-to-noise ratio at frequency bands of interest.一種用於收集資料之裝置，具有第一及第二電極。第一電極耦合至所要一表面，而第二電極耦合至「其他每一事物」或「空氣」。第一電極乃經屏蔽，以隔開第二電極及大多數寄生電容來源；此一屏蔽物乃由一主動驅動器所驅動，而驅動器驅動屏蔽物以追蹤(理想上並可匹配)該電極之瞬間電位。第二電極亦以類似方式同樣予以屏蔽，隔開大多數寄生電容來源。此等屏蔽物，同樣有助於拘限其由裝置電子之RFI(射頻干擾)耦合任一電極之延伸範圍。經由此種方式，感測裝置遂於所要頻帶上，獲致明顯更佳之訊雜比。
