Optical Methods in Sensing and Imaging for Medical and Biological Applications

The recent advances in optical sources and detectors have opened up new opportunities for sensing and imaging techniques which can be successfully used in biomedical and healthcare applications. This book, entitled ‘Optical Methods in Sensing and Imaging for Medical and Biological Applications’, focuses on various aspects of the research and development related to these areas. The book will be a valuable source of information presenting the recent advances in optical methods and novel techniques, as well as their applications in the fields of biomedicine and healthcare, to anyone interested in this subject

Conduit Artery Photoplethysmography and its Applications in the Assessment of Hemodynamic Condition

Elektroniskā versija nesatur pielikumusPromocijas darbā ir izstrādāta maģistrālo artēriju fotopletizmogrāfijas (APPG) metode hemodinamisko parametru novērtējumam. Pretstatot referentām metodēm, demonstrēta iespēja iegūt arteriālo elasticitāti raksturojošus parametrus, izmantojot APPG signāla formas analīzi (atvasinājuma un signāla formas aproksimācijas parametri) un ar APPG iegūtu pulsa izplatīšanās ātrumu unilaterālā gultnē. Izstrādāta APPG reģistrācijas standartizācija, mērījuma laikā nodrošinot optimālo sensora piespiedienu. Šis paņēmiens validēts ārējās ietekmes (sensora piespiediens) un hemodinamisko stāvokļu (perifērā vaskulārā pretestība) izmaiņās femorālā APPG signālā, identificējot būtiskākos faktorus APPG pielietojumos. Veikta APPG validācija asinsrites fizioloģijas un preklīniskā pētījumā demonstrējot APPG potenciālu pētniecībā un diagnostikā. Izstrādāts pulsa formas parametrizācijas paņēmiens, saistot fizioloģiskās un aproksimācijas modeļa komponentes. Atslēgas vārdi: maģistrālā artērija, fotopletizmogrāfija, arteriālā elasticitāte, metodes standartizācija, pulsa formas kvantifikācija, vazomocija, sepseThe doctoral thesis features the development of a conduit artery photoplethysmography technique (APPG) for the evaluation of hemodynamic parameters. Contrasting referent methods, the work demonstrates the possibility to receive parameters characterizing the arterial stiffness by means of APPG waveform analysis (derivation and waveform approximation parameters) and APPG obtained pulse wave velocity in a unilateral vascular bed. In this work APPG standardization technique was developed providing optimal probe contact pressure conditions. It was validated by altering the external factors (probe contact pressure) and hemodynamic conditions (peripheral vascular resistance) on the femoral APPG waveform identifying the key factors in APPG applications. The APPG validation in blood circulation physiology and a pre-clinical trial was performed demonstrating APPG potential in the extension of applications. An arterial waveform parameterization was developed relating the physiological wave to approximation model components. Keywords: conduit artery, photoplethysmography, arterial stiffness, method standardization, waveform parametrization, vasomotion, sepsi

Smart Sensors for Healthcare and Medical Applications

This book focuses on new sensing technologies, measurement techniques, and their applications in medicine and healthcare. Specifically, the book briefly describes the potential of smart sensors in the aforementioned applications, collecting 24 articles selected and published in the Special Issue “Smart Sensors for Healthcare and Medical Applications”. We proposed this topic, being aware of the pivotal role that smart sensors can play in the improvement of healthcare services in both acute and chronic conditions as well as in prevention for a healthy life and active aging. The articles selected in this book cover a variety of topics related to the design, validation, and application of smart sensors to healthcare

Blood pressure estimation using pulse transit time models

Abstract. Blood pressure (BP) is an important indicator of human health. Common methods for measuring BP continuously are either invasive, intermittent or they require using a cumbersome cuff. Pulse Transmit Time (PTT) -based measurement can be an alternative for such methods, as it ensures continue and non-invasive monitoring. However, since the method is indirect, it requires careful modelling of PTT-BP relation. In this thesis, three approaches of BP estimation from PTT are tested: linear regression, nonlinear Moens and Korteweg model and nonlinear model developed by Gesche. In the experiments, cardiovascular pulses for PTT were sensed using two fiber optics based accelerometers developed at the University of Oulu. To evaluate feasibility of presented models, the results were compared with reference BP values, measured using methods accepted for the commercial use. There were two groups of data. One was compared with BP measured using invasive catheter. Second group was compared with BP measured using volume clamp method. Obtained results suggest, that the presented calculation methods in present state still require further development in order to provide accurate BP values, however, they can be potentially used for observation of BP changes

Soft Electronics and Sensors for Wearable Healthcare Applications

Wearable electronics are becoming increasingly essential to personalized medicine by collecting and analyzing massive amounts of biological signals from internal organs, muscles, and blood vessels. Conventional rigid electronics may lead to motion artifacts and errors in collected data due to the mismatches in mechanical properties between human skin. Instead, soft wearable electronics provide a better platform and interface that can form intimate contact and conformably adapt to human skin. In this respect, this thesis focuses on new materials formulation, fabrication, characterization of low-cost, high sensitivity and reliable sensors for wearable health monitoring applications. More specifically, we have studied the silver nanoparticles (AgNPs) inkjet-printed on a polydimethylsiloxane (PDMS) substrate that offers great pressure sensitivity for aterial pulse monitoring. In addition, we have investigated the conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and poly(ethylene oxide) PEO polymer blends that exhibit low sheet resistance and can resist up to 50\% of tensile strain. The highly stretchable thin film can serve as interconnects between electronic components and dry electrodes for photoplethysmography (PPG) and electrocardiography (ECG) recordings. Based on the developed PEDOT:PSS solution with high conductivity, we fabricated a porous PDMS sponge coated with conductive PEDOT:PSS to make electrodes with reduced electrode-skin contact impedance, improved signal-to-noise ratio and is suited for long-term and motion-artifact-tolerant recording of high quality biopotential signals including ECG and electromyography (EMG). Finally, we demonstrated a multimodal sensor based on the porous PEDOT:PSS/PDMS sponge for sensing and distinguishing of pressure, strain and temperature from different trends in resistance and capacitance response. Applications including object detection, gesture recognition and temperature sensing have all been demonstrated. In this thesis, the proposed materials, sensor design, low-cost inkjet printing and dip-coating fabrication process open the possibility for more complex epidermal wearable health monitoring electronic systems

XXII International Conference on Mechanics in Medicine and Biology - Abstracts Book

This book contain the abstracts presented the XXII ICMMB, held in Bologna in September 2022. The abstracts are divided following the sessions scheduled during the conference

The use of near infrared spectroscopy (NIRS) to measure vascular haemodynamics in human bone tissue in vivo

Rationale: Poor cardiovascular health is associated with reduced bone strength and increased risk of fragility fracture. However, direct measurement of intraosseous vascular health is difficult due to the density and mineral content of bone. The aim of this PhD project was to investigate the feasibility of near infrared spectroscopy (NIRS) for the investigation of vascular haemodynamics in human bone in vivo. NIRS provides inexpensive, non-invasive, safe, and real time data on changes in oxygenated and deoxygenated haemoglobin concentration at superficial anatomical sites. NIRS utilises a source optode of near infrared (NIR) light and detector optode that obtains representative data of the interactions of NIR photons with tissue. Method: A systematic review was performed identifying the current existing applications of NIRS (and similar technologies) for measuring human bone tissue in vivo. This review informed the development of an arterial occlusion protocol for obtaining haemodynamic measurements of the proximal tibia and lateral calf, including assessment of the protocol’s reliability. For thirty-six participants, NIRS results were also compared to alternative tests of bone haemodynamics involving dynamic contrast enhanced MRI (DCE-MRI), and measures of general bone health based on dual x-ray absorptiometry testing and blood markers of bone metabolism. Results: This thesis presents novel data demonstrating NIRS can obtain acceptably reliable markers of haemodynamics at the proximal tibia in vivo, comparable with reliability assessments of alternative modalities measuring intraosseous haemodynamics, and the use of NIRS for measuring muscle. Novel associations have been demonstrated between haemodynamic markers measured with NIRS and DCE-MRI, giving confidence NIRS truly represents bone haemodynamics. Increased NIRS markers of oxygen extraction during occlusion, and greater post-ischaemic vascular response to occlusion, were both associated with greater bone mineral density. Conclusion: As a feasibility study, this PhD project has demonstrated the potential for NIRS to contribute to research around the potential pathophysiological role of vascular dysfunction within bone tissue, but also the limitations and need for further development of NIRS technology.The Royal College of Radiologist

Clinical evaluation of a new optical fibre method of measuring oxygen saturation using photoplethysmograph signals reflected from internal tissues

MD (Res)Traditional methods of measuring oxygen saturation, e.g. pulse oximetry, depend on an adequate peripheral circulation and have a 20–30 second lag time before readings are obtained. This was a series of evaluations of novel optical probes, designed to measure oxygen saturation using fibreoptic technology directly from internal organs including the brain, oesophagus and organs with splanchnic circulations. A series of pilot studies were proposed and research ethics approval obtained to carry out studies in humans, under general anaesthesia, using these probes. Innovative reflectance probes were designed specifically for each of the four applications, so as to obtain potentially useful signals needed for signal processing, analysis and evaluation. Signals were successfully obtained from the brain, oesophagus and splanchnic region in almost all of the patients recruited. Good quality photoplethysmograph signals were recorded and these were translated into clinically meaningful values of oxygen saturation comparable to traditional methods of pulse oximetry. Overall, the signals were prone to movement artefacts as well as occasional interference from surgical diathermy and other sources. Nonetheless, the probes could prove to be a useful alternative to conventional external transmittance pulse oximetry methods as well as providing useful information regarding regional perfusion and oxygenation. The success of these pilot studies will form the basis of more research in the area and further development of such probes on the medical engineering front