2026-09-19T08:04:52Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/361842022-01-13T07:54:29Zcom_1721.1_7582com_1721.1_7581col_1721.1_131022
Rahul Sarpeshkar.
Tavakoli Dastjerdi, Maziar, 1976-
Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.
Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science
2007-02-21T11:58:45Z
2007-02-21T11:58:45Z
2006
2006
http://hdl.handle.net/1721.1/36184
74907293
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.
Includes bibliographical references (p. 210-216).
Pulse oximetry is a fast, noninvasive, easy-to-use, and continuous method for monitoring the oxygen saturation of a patient's blood. In modem medical practice, blood oxygen level is considered one of the important vital signs of the body. The pulse oximeter system consists of an optoelectronic sensor that is normally placed on the subject's finger and a signal processing unit that computes the oxygen saturation. It uses red and infrared LEDs to illuminate the subject's finger. We present an advanced logarithmic photoreceptor which takes advantage of techniques such as distributed (cascaded) amplification, automatic loop gain control, and parasitic capacitance unilateralization to improve the performance and ameliorate certain shortcomings of existing logarithmic photoreceptors. These improvements allow us to reduce LED power significantly because of a more sensitive photoreceptor. Furthermore, the exploitation of the logarithmic nonlinearity inherent in transistors eliminates the need of performing some of the mathematical operations which are traditionally done in digital domain to calculate oxygen saturation and allows for a very area-efficient all-analog implementation. The need for an ADC and a DSP is thus completely eliminated.
(cont.) We show that our analog pulse oximeter constructed with red and infrared LEDs and our novel photoreceptor at its front end consumes 4.8mW of power whereas a custom-designed ASIC digital implementation (employing a conventional linear photoreceptor) and the best commercial pulse oximeter are estimated to dissipate 15.7mW and 55mW, respectively. The direct result of such power efficiency is that while the batteries in this commercial oximeter need replacement every 5 days (assuming four "AAA" 1.5V batteries are used), our analog pulse oximeter allows 2 months of operation. 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.
by Maziar Tavakoli Dastjerdi.
Ph.D.
216 p.
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.
http://dspace.mit.edu/handle/1721.1/7582
Electrical Engineering and Computer Science.
An analog VLSI front end for pulse oximetry
Analog very large scale integration front end for pulse oximetry
Thesis
application/pdf
false
Publication
unknown
unknown
<Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="9054bd89-98dd-474a-969b-71b7bb5ef873">
<Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type>
<Language>eng</Language>
<Title>An analog VLSI front end for pulse oximetry</Title>
<Subtitle>Analog very large scale integration front end for pulse oximetry</Subtitle>
<PublishedIn>
<Publication>
</Publication>
</PublishedIn>
<PublicationDate>2006</PublicationDate>
<Authors>
<Author>
<DisplayName>Tavakoli Dastjerdi, Maziar, 1976-</DisplayName>
<Affiliation>
<OrgUnit>
</OrgUnit>
</Affiliation>
</Author>
</Authors>
<Editors>
</Editors>
<Publishers>
<Publisher>
<DisplayName>Massachusetts Institute of Technology</DisplayName>
<OrgUnit />
</Publisher>
</Publishers>
<License>http://dspace.mit.edu/handle/1721.1/7582</License>
<Keyword>Electrical Engineering and Computer Science.</Keyword>
<Abstract>Pulse oximetry is a fast, noninvasive, easy-to-use, and continuous method for monitoring the oxygen saturation of a patient's blood. In modem medical practice, blood oxygen level is considered one of the important vital signs of the body. The pulse oximeter system consists of an optoelectronic sensor that is normally placed on the subject's finger and a signal processing unit that computes the oxygen saturation. It uses red and infrared LEDs to illuminate the subject's finger. We present an advanced logarithmic photoreceptor which takes advantage of techniques such as distributed (cascaded) amplification, automatic loop gain control, and parasitic capacitance unilateralization to improve the performance and ameliorate certain shortcomings of existing logarithmic photoreceptors. These improvements allow us to reduce LED power significantly because of a more sensitive photoreceptor. Furthermore, the exploitation of the logarithmic nonlinearity inherent in transistors eliminates the need of performing some of the mathematical operations which are traditionally done in digital domain to calculate oxygen saturation and allows for a very area-efficient all-analog implementation. The need for an ADC and a DSP is thus completely eliminated.</Abstract>
<Abstract>(cont.) We show that our analog pulse oximeter constructed with red and infrared LEDs and our novel photoreceptor at its front end consumes 4.8mW of power whereas a custom-designed ASIC digital implementation (employing a conventional linear photoreceptor) and the best commercial pulse oximeter are estimated to dissipate 15.7mW and 55mW, respectively. The direct result of such power efficiency is that while the batteries in this commercial oximeter need replacement every 5 days (assuming four "AAA" 1.5V batteries are used), our analog pulse oximeter allows 2 months of operation. 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.</Abstract>
<Access xmlns="http://purl.org/coar/access_right"
>
</Access>
</Publication>