High-performance flexible energy storage and harvesting system for wearable electronics.

This paper reports on the design and operation of a flexible power source integrating a lithium ion battery and amorphous silicon solar module, optimized to supply power to a wearable health monitoring device. The battery consists of printed anode and cathode layers based on graphite and lithium cobalt oxide, respectively, on thin flexible current collectors. It displays energy density of 6.98 mWh/cm(2) and demonstrates capacity retention of 90% at 3C discharge rate and ~99% under 100 charge/discharge cycles and 600 cycles of mechanical flexing. A solar module with appropriate voltage and dimensions is used to charge the battery under both full sun and indoor illumination conditions, and the addition of the solar module is shown to extend the battery lifetime between charging cycles while powering a load. Furthermore, we show that by selecting the appropriate load duty cycle, the average load current can be matched to the solar module current and the battery can be maintained at a constant state of charge. Finally, the battery is used to power a pulse oximeter, demonstrating its effectiveness as a power source for wearable medical devices

Towards Stable Electrochemical Sensing for Wearable Wound Monitoring

Wearable biosensing has the tremendous advantage of providing point-of-care diagnosis and convenient therapy. In this research, methods to stabilize the electrochemical sensing response from detection of target biomolecules, Uric Acid (UA) and Xanthine, closely linked to wound healing, have been investigated. Different kinds of materials have been explored to address such detection from a wearable, healing platform. Electrochemical sensing modalities have been implemented in the detection of purine metabolites, UA and Xanthine, in the physiologically relevant ranges of the respective biomarkers. A correlation can be drawn between the concentrations of these bio-analytes and wound severity, thus offering probable quantitative insights on wound healing progression. These insights attempt to contribute in reducing some impacts of the financial structure on the healthcare economy associated with wound-care. An enzymatic electrochemical sensing system was designed to provide quick response at a cost-effective, miniaturized scale. Robust enzyme immobilization protocols have assisted in preserving enzyme activity to offer stable response under relevant variations of temperature and pH, from normal. Increased hydrophilicity of the sensor surface using corona plasma, has assisted in improving conductivity, thus allowing for increased electroactive functionalization and loading across the substrate’s surface. Superior sensor response was attained from higher loading of nanomaterials (MWCNT/AuNP) and enzymes (UOx/XO) employed in detection. Potentiometric analyses of the nanomaterial modified enzymatic biosensors were conducted using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) modalities. Under relevant physiological conditions, the biosensor was noted to offer a variation in response between 10 % and 30 % within a week. Stable, reproducible results were obtained from repeated use of the biosensor over multiple days, also offering promise for continuous monitoring. Shelf life of the biosensor was noted to be more than two days with response retained by about 80 % thereafter. Secondary analyses have been performed utilizing the enzymatic biosensor to explore the feasibility of target biomarker detection from clinical extracts of different biofluids for wound monitoring. Biosensor response evaluation from the extracts of human wound exudate, and those obtained from perilesional and healthy skin, provided an average recovery between 107 % and 110 % with a deviation within (+/-) 6 %. Gradual decrease in response (10-20 %) was noted in detection from extracts further away from injury site. Increased accumulation of biofluids on the sensor surface was studied to explore sensor response stability as a function of sample volume. With a broad linear range of detection (0.1 nM – 7.3 mM) and detection limits lower than the physiological concentrations, this study has assessed the viability of stable wound monitoring under physiologically relevant conditions on a wearable platform

Smartphone-Based pH Sensor for Home Monitoring of Pulmonary Exacerbations in Cystic Fibrosis.

Currently, Cystic Fibrosis (CF) patients lack the ability to track their lung health at home, relying instead on doctor checkups leading to delayed treatment and lung damage. By leveraging the ubiquity of the smartphone to lower costs and increase portability, a smartphone-based peripheral pH measurement device was designed to attach directly to the headphone port to harvest power and communicate with a smartphone application. This platform was tested using prepared pH buffers and sputum samples from CF patients. The system matches within ~0.03 pH of a benchtop pH meter while fully powering itself and communicating with a Samsung Galaxy S3 smartphone paired with either a glass or Iridium Oxide (IrOx) electrode. The IrOx electrodes were found to have 25% higher sensitivity than the glass probes at the expense of larger drift and matrix sensitivity that can be addressed with proper calibration. The smartphone-based platform has been demonstrated as a portable replacement for laboratory pH meters, and supports both highly robust glass probes and the sensitive and miniature IrOx electrodes with calibration. This tool can enable more frequent pH sputum tracking for CF patients to help detect the onset of pulmonary exacerbation to provide timely and appropriate treatment before serious damage occurs

Low-power Wearable Healthcare Sensors

Advances in technology have produced a range of on-body sensors and smartwatches that can be used to monitor a wearer’s health with the objective to keep the user healthy. However, the real potential of such devices not only lies in monitoring but also in interactive communication with expert-system-based cloud services to offer personalized and real-time healthcare advice that will enable the user to manage their health and, over time, to reduce expensive hospital admissions. To meet this goal, the research challenges for the next generation of wearable healthcare devices include the need to offer a wide range of sensing, computing, communication, and human–computer interaction methods, all within a tiny device with limited resources and electrical power. This Special Issue presents a collection of six papers on a wide range of research developments that highlight the specific challenges in creating the next generation of low-power wearable healthcare sensors

Redesigning chemical analysis: transducing information from chemical into digital

Aquesta tesi planteja que les xarxes distribuïdes de detecció de substàncies químiques serán eines beneficioses per aconseguir millors resultats de salut com a éssers humans, així com per a guiarnes en el nostre paper autodeterminat con a guardians en l'àmbit ecològic. Tot aixo, des de la perspectiva d’introduir elements de disseny en les eines analítiques. El treball comença amb una introducció a la visió de com els sensors químics s'adapten als contextos més grans de la biologia, la història i la tecnologia. El segon capítol ofereix una base de coneixements sobre els mètodes i principis científics i tecnològics subjacents sobre els quals es basa aquest treball. A continuació, es fa una revisió crítica dels avenços acadèmics cap als sensors electroquímics distribuïts, que divideixen el problema en tres aspectes: rendiment adequat, usabilitat intuïtiva i assequibilitat. Entre aquests, la usabilitat s'identifica com el coll d'ampolla principal en l'adopció generalitzada de sensors químics centrats en l'usuari. Els capítols posteriors ofereixen algunes respostes als reptes, en forma de treball experimental original. Encara que aquest treball es basa en l'electroquímica analítica, s'aborda des d’una metodologia de disseny, amb iteracions d'anàlisi i síntesi incrustades en el procés d'ideació. Les declaracions finals reflexionen sobre el treball com una petita part en una creixent revolució de l'edat de la informació química; com una petita esquerda a la presa que contenia una allau de dades químiques de diagnòstic amb conseqüències imprevisibles, però positives i revolucionàries.Esta tesis postula que las redes distribuidas de detección química serán herramientas beneficiosas para alcanzar mejores resultados de salud como seres humanos, así como para guiarnos en nuestro papel autodeterminado como guardianes en la esfera ecológica. Todo esto desde una perspectiva de introducir elementos de diseño en herramientas analíticas. El trabajo comienza con una introducción a la visión de cómo los sensores químicos se ajustan a los contextos más amplios de la biología, la historia y la tecnología. El segundo capítulo proporciona algunos antecedentes de los métodos y principios científicos y tecnológicos subyacentes en los que se basa este trabajo. Esto es seguido por una revisión crítica de los avances académicos hacia sensores electroquímicos distribuidos, que divide el problema en tres aspectos: rendimiento apropiado, usabilidad intuitiva y asequibilidad. Entre estos, la usabilidad se identifica como el cuello de botella principal en la adopción generalizada de sensores químicos centrados en el usuario. Los siguientes capítulos ofrecen algunas respuestas a los desafíos, en forma de trabajo experimental original. Mientras que este trabajo se arraiga en la electroquímica analítica, se aborda desde una metodología de diseño, con iteraciones de análisis y síntesis integradas en el proceso de ideación. Las declaraciones finales reflejan el trabajo como una pequeña parte en una floreciente revolución de la era de la información química; como una pequeña grieta en la presa que contiene una avalancha de datos químicos de diagnóstico con consecuencias imprevisibles, pero positivas y revolucionarias.This thesis posits that distributed chemical sensing networks will be beneficial tools towards our greater health outcomes as humans, as well as in guiding us in our self-determined role as custodians over the ecological sphere. A perspective of infusing design elements and approaches into analytical tools is shared. The work begins with an introduction presenting a vision of how chemical sensors fit within the greater contexts of biology, history, and technology. The second chapter provides some background to the underlying scientific and technological methods and principles on which this work stands. This is followed by a critical review of the academic advances towards distributed electrochemical sensors, which divides the problem into three aspects of appropriate performance, intuitive usability, and affordability. Amongst these, usability is identified as the principal bottleneck in the widespread adoption of user-centered chemical sensors. The subsequent chapters offer some responses to the challenges, in the form of original experimental work. While rooted in analytical electrochemistry, the work is approached with a design methodology, with iterations of analysis and synthesis embedded in the ideation process. Concluding statements reflect on the work as a small part in a burgeoning revolution of the chemical information age; as a minor crack in the dam holding back a flood of diagnostic chemical data with unforeseeable, yet positive and revolutionary consequences

Towards self-powered and autonomous wearable glucose sensor

Blood glucose diagnostic systems are a world-wide success story. Nevertheless, all the painless solutions available are too expensive to be disposable. We aim to bridge this gap by developing a painless disposable diabetes diagnostic patch. Our envisaged device is fully integrated and autonomous: harvests the required energy from the environment and features sensor autocalibration in real-time. In this paper, we present the design and preliminary results of the different parts in the wearable patch: electrochemical glucose sensor developed on scalable PCB technology, biofuel cell based on glucose in the biofluid sample, and instrumentation electronics designed on a PCB with energy and data management blocks