{"id":1436,"date":"2010-07-07T10:58:37","date_gmt":"2010-07-07T14:58:37","guid":{"rendered":"https:\/\/wpmu2.mit.local\/?p=1436"},"modified":"2010-07-07T10:58:37","modified_gmt":"2010-07-07T14:58:37","slug":"an-ultra-low-power-pulse-oximeter-implemented-with-an-energy-efficient-transimpedance-amplifier","status":"publish","type":"post","link":"https:\/\/wpmu2.mit.local\/an-ultra-low-power-pulse-oximeter-implemented-with-an-energy-efficient-transimpedance-amplifier\/","title":{"rendered":"An Ultra-low-power Pulse Oximeter Implemented with an Energy-efficient Transimpedance Amplifier"},"content":{"rendered":"

Pulse oximeters are ubiquitous in modern medicine for non-invasively measuring the percentage of oxygenated hemoglobin in a patient\u2019s blood by comparing transmission characteristics of red and infrared LED light through the patient\u2019s finger with a photoreceptor. We developed an analog single-chip pulse oximeter with 4.8-mW total power dissipation, which is an order of magnitude below our measurements on commercial implementations [1<\/a>]<\/sup>. The majority of this power reduction is due to the use of a novel logarithmic transimpedance amplifier with inherent contrast sensitivity, distributed amplification, unilateralization, and automatic loop gain control. The transimpedance amplifier together with a photodiode current source form a high-performance photoreceptor with characteristics similar to those found in nature.\u00a0 Therefore, our oximeter is well suited for portable medical applications such as continuous home-care monitoring for elderly or chronic patients, emergency patient transport, remote soldier monitoring, and wireless medical sensing. Furthermore, our design obviates the need for an A-to-D and DSP and leads to a small single-chip solution.<\/p>\n\n\t\t