The ability of pulse oximeters to measure carboxyhemoglobin (HbCO) in blood or measure accurate values of oxygen saturation (SpO2) in the presence of elevated levels of HbCO is an important advantage because high exposure to carbon monoxide (CO) can be fatal or results in permanent neurological damage. The aim of my research was to develop an algorithm that would measure SpO2 and SpCO simultaneously using a pulse oximeter. Several specific wavelengths at which changes in SpCO and SpO2 can be measured with high sensitivity and specificity were identified. The choice of these wavelengths was experimentally verified utilizing an in-vitro set up. Preliminary results using our algorithm showed an accuracy of -1.1 to +2.7% [±1.96 SD] for SpO2 ranging between 70-100%, and -2 to 3.3% [±1.96 SD] for SpCO ranging between 30% with a specificity of 83.3% and a sensitivity of 100% for SpO2 and SpCO, respectively.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Delayed control of haemorrhage or blood loss has been recognised as a major contributor to preventable trauma deaths, but early detection of internal bleeding is difficult due to unreliability of heart rate (HR) and blood pressure (BP) as markers of volume status. This thesis explores a novel method of early blood loss detection using a noninvasive finger photoplethysmographic (PPG) pulse oximetry waveform that is normally utilised in pulse oximeters for estimating arterial oxygen saturation. Graded head-up tilt (n = 13) and blood donation (n = 43) in human volunteers were selected as experimental models of mild to moderate blood loss. From the tilt study, a novel method for automatically detecting left ventricular ejection time (LVET) from the finger PPG waveform has been developed and verified by comparison with the LVET measured from aortic flow velocity. PPG waveform derived LVET (LVETp) and pulse transit time (PTT) were strongly correlated with aortic LVET and pre-ejection period respectively (median r = 0.954 and 0.964) and with the decrease in central blood volume indicated by the sine of the tilt angle (median r = -0.985 and 0.938), outperforming R-R interval (RRI) and BP in detecting mild central hypovolaemia. In the blood donation study, progressive blood loss was characterised by falling LVETp and rising PTT (p < 0.01). A new way of identifying haemorrhagic phases by monitoring changes and trends in LVETp, PTT and RRI has been proposed based on the results from the two studies. The utility of frequency spectrum analysis of PPG waveform variability (PPGV) in characterising blood loss has also been examined. A new technique of PPGV analysis by computing the coherence-weighted cross-spectrum has been proposed. It has been shown that the spectral measures of finger PPGV exhibited significant changes (p < 0.01) with blood donation and were mildly correlated with systemic vascular resistance in intensive care unit patients (r from 0.53 to 0.59, p < 0.0001), therefore may be useful for identification of different haemorrhagic phases. In conclusion, this thesis has established finger PPG waveform as a potentially useful noninvasive tool for early detection of blood loss.

The process of pulse diagnosis was examined in a sample of 100 patients randomly selected from the author's acupuncture clinic. Patient symptoms, pulses (as utilised in traditional Chinese medicine), diagnostic criteria (as described in traditional Chinese medicine), acupuncture points selected and patient comments after each treatment were coded into a numerical format suitable for stepwise multiple regression and crosstabulation analysis. The analysis indicated that the interpretation of pulse qualities predicted the diagnostic criteria when used in accordance with the theories of acupuncture. The selection of acupuncture points could not be predicted from the diagnostic criteria when using pulse diagnosis. Additionally the analysis indicated that the patient comments after acupuncture were independent of the initial patient symptoms. More research is needed to more fully understand the process of pulse diagnosis. However the analysis does suggest that pulse diagnosis should be incorporated into acupuncture curricula in both traditional acupuncture courses and medical acupuncture courses.

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: ultrasound modeling; annular arrays. Includes bibliographical references (p.197-198).

Femtosecond laser pulse has been used for the machining of the gratings primarily due to its superior advantages over conventional continuous wave (CW) and long pulse lasers for micromachining. In this paper, we develop a novel technique for the fabrication of planar gratings by colliding two beams to generate interference fringes. This technique is simple, fast and low cost. We have successfully fabricated planar gratings on a copper substrate. / Singapore-MIT Alliance (SMA)

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: Biome, pulse oximeter, wearable sensors, telemedicine. Includes bibliographical references (leaves 115-119 ).

No description available.

Ultra Wide Band (UWB) is a short-pulse electrical signal which is widely used for short distant wireless communication because its low path loss, good immunity to multipath propagation, and high data rate. The reason of using optical fiber as carrier is fiber can bust up the communication capacitance in long distance range because of high capacitance, low loss propagation. Thereby, the technique of UWB signal on fiber has become more and more important. In this work, a novel method using electro-absorption modulation with short termination for interface of optical fiber and generate UWB signal is proposed and demonstrated. The structure is simple.This method don¡¦t need employing any complicated frequency mixer, or complex systems. This work need to generate optical pulse with high energy, which is feded into the EAM. The signal can generate electrical pulse and build electrical field on EAM in the same time. The optical pulse is modulated by the electrical field on EAM. Using this way, we can generate UWB optical signal.

In this thesis, a novel method for multi-pulse with equal chirp characteristics and more efficient THz generation through two photon absorption (TPA) are investigated and demonstrated. These are all the first time, for our best knowledge, odd multi-pulses generation and innovative approach for efficient THz through TPA are proposed and studied. By modulating the amplitude and phase of the spatial light modulator with the pulse shaper, the number of multi-pulses can be adjustable without the limitation of even number only. Meanwhile, the chirp properties of the generated pulses are with the same characteristics and tunable also. For the case with bandwidth of 10nm, the generated multi-pulses with equal chirps varying from -20000fs^2 to 20000fs^2 are demonstrated and the results have a good agreement with the theoretical estimation. We also discuss the number of the multi-pulses and inequalities of the amplitude of the pulses are limited by the spectral resolution of SLM within the pulse shaper. Regarding to efficient THz radiation, it can be generated more efficiently from a low-temperature-grown GaAs (LT-GaAs) photoconductive (PC) antenna by taking into account the TPA induced photo-carrier in the photoconductor. A rate-equation-based approach using the Drude-Lorentz model taking into account the band-diagram of LT-GaAs is used for the theoretical analysis. The super-linear power dependent photocurrent clarifies the role of TPA. Previously unnoticed THz pulse features and anomalously increasing THz radiation power rather than saturation were observed. These are in good agreement with the theoretical predictions.