A pulse oximetry sensor has an emitter adapted to transmit optical radiation of at least two wavelengths into a tissue site and a detector adapted to receive optical radiation from the emitter after tissue site absorption. The interconnect structure includes a plurality of layers. According to another set of embodiments, techniques are provided for determining electronic document information for paper documents. While the disk is rotated unidirectionally, the electron beam is deflected in the radial direction within a single track of the disk to draw the first elements.