Impedance phlebography based pulse sensing using inductively-coupled inkjet-printed WRAP sensor

While mobile health (mHealth) provides tremendous opportunity to monitor patient health, continuous monitoring of various physiological data can be enhanced with body-worn sensors. In this paper, we demonstrate impedance phlebography (IPG) based pulse sensing using inductively coupled Wireless Resistive Analog Passive (WRAP) sensors that are prototyped on paper using inkjet printing (IJP) technique. The prototyped sensors were flexible and easy to attach to the body. The wireless scanning was performed at 13.56 MHz utilizing inductive coupling technique. The sensor composes of only a planar spiral coil (PSC), a tuning capacitor, and a MOSFET transducer. The IPG data was collected from IJP printed pads (5mm×10mm). The envelop of the captured signals correspond to the pulse and verified with a pulse oximeter. The computed pulse rate was 72 bpm with a 5-sec. capture window, an acceptable error of 3.5%. The prototype showed the possibility to develop WRAP sensors with IJP technique for various physiological signals that might further enhance mHealth capabilities for improved healthcare.