Steve Warren

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Recent technological advances in sensors, low-power integrated circuits, and wireless communications have enabled the design of low-cost, miniature, lightweight, intelligent physiological sensor platforms that can be seamlessly integrated into a body area network for health monitoring. Wireless body area networks (WBANs) promise unobtrusive ambulatory(More)
Medical devices historically have been monolithic units — developed, validated, and approved by regulatory authorities as stand-alone entities. Modern medical devices increasingly incorporate connectivity mechanisms that offer the potential to stream device data into electronic health records, integrate information from multiple devices into single(More)
In this work, we present novel methods for detecting the presence of motion artifact in photoplethysmographic (PPG) measurements based on higher order statistical information present in the data. We analyze both clean and corrupt PPG data in the time and frequency domains. In the time domain, skew and kurtosis measures of the signal are used as(More)
This material is based upon work supported by the National Science Foundation (NSF) under grants ITR–0205487, BES–0093916, and EPS– 9874732 (with matching support from the State of Kansas). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF.(More)
A four-phase integrated buck converter in 45 nm silicon-on-insulator (SOI) technology is presented. The controller uses unlatched pulse-width modulation (PWM) with nonlinear gain to provide both stable small-signal dynamics and fast response ( 700 ps) to large input and output transients. This fast control approach reduces the required output capacitance by(More)
Laparoscopic surgery for rectal cancer is now well established. Recent studies have shown no difference in survival or oncologic outcomes when laparoscopic surgery is compared to open procedures [1, 2]. The laparoscopic approach does, however, present the surgeon with inherent challenges. Previous abdominal surgery, tumours closer to the anal verge, high(More)
Corruption of photopleythysmograms (PPGs) by motion artifacts has been a serious obstacle to the reliable use of pulse oximeters for real-time, continuous state-of-health monitoring. In this paper, we propose an automated, two-stage PPG data processing method to minimize the effects of motion artifacts. The technique is based on our prior work related to(More)
Onboard assessment of photoplethysmogram (PPG) quality could reduce unnecessary data transmission on battery-powered wireless pulse oximeters and improve the viability of the electronic patient records to which these data are stored. These algorithms show promise to increase the intelligence level of former "dumb" medical devices: devices that acquire and(More)
Pulse oximeters are central to the move toward wearable health monitoring devices and medical electronics either hosted by, e.g., smart phones or physically embedded in their design. This paper presents a small, low-cost pulse oximeter design appropriate for wearable and surface-based applications that also produces quality, unfiltered photo-plethysmograms(More)
Motion artifact reduction and separation become critical when medical sensors are used in wearable monitoring scenarios. Previous research has demonstrated that independent component analysis (ICA) can be applied to pulse oximeter signals to separate photoplethysmographic (PPG) data from motion artifacts, ambient light, and other interference in low-motion(More)