Fig. 1From: Non-invasive venous waveform analysis (NIVA) for volume assessment in patients undergoing hemodialysis: an observational studyNIVA prototype. (a) The NIVA device consists of a piezo electric crystal sensor and housing control box that is (b) applied to the surface of the skin over the venous plexus at the volar aspect of the wrist. The current from the crystal is transferred via wire to the control box where the signal is amplified and converted to a digital signal and transferred via USB port to a computer for analysisBack to article page