Real-time sweat pH monitoring based on a wearable chemical barcode micro-fluidic platform incorporating ionic liquids

This work presents the fabrication, characterisation and the performance of a wearable, robust, flexible and disposable chemical barcode device based on a micro-fluidic platform that incorporates ionic liquid polymer gels (ionogels). The device has been applied to the monitoring of the pH of sweat in real time during an exercise period. The device is an ideal wearable sensor for measuring the pH of sweat since it does not contents any electronic part for fluidic handle or pH detection and because it can be directly incorporated into clothing, head- or wristbands, which are in continuous contact with the skin. In addition, due to the micro-fluidic structure, fresh sweat is continuously passing through the sensing area providing the capability to perform continuous real time analysis. The approach presented here ensures immediate feedback regarding sweat composition. Sweat analysis is attractive for monitoring purposes as it can provide physiological information directly relevant to the health and performance of the wearer without the need for an invasive sampling approac

Wearable chemo/bio-sensors for sweat sensing in sports applications: combining micro-fluidics and novel materials

In the last decade, we have witnessed an exponential growth in the area of clinical diagnostic but surprisingly little has been done on the development of wearable chemo/bio-sensors in the field of sports science. In particular, the use of wearable wireless sensors capable of analysing sweat during physical exercise can provide access to new information sources that can be used to optimise and manage athletes’ performance. Lab-on-a-Chip technology provides a fascinating opportunity for the development of such wearable sensors. In this thesis two different colorimetric wearable microfluidic devices for real- time pH sensing were developed and used during athlete training activity. In one case a textile-based microfluidic platform employing cotton capillarity to drive sweat toward the pH sensitive area is presented that avoids the use of bulky fluid handling apparatus, i.e. pumps. The second case presents a wearable micro-fluidic device based on the use of pH responsive ionogels to obtain real-time sweat pH measurements through photo analysis of their colour variation. The thesis also presents the first example of sweat lactate sensing using an organic electrochemical transistor incorporating an ionogel as solid-state electrolyte. In this chapter, optimization of the lactate oxidase stability when dissolved in number of hydrated ionic liquids is investigated. Finally, a new fabrication protocol for paper-based microfluidic technology is presented, which may have important implications for future applications such as low-cost diagnostics and chemical sensing technologies

Engineering multifunctional adhesive hydrogel patches for biomedical applications

Traditional patches, such as sticking plaster or acrylic adhesives used for over a hundred years, lack functionality. To address this issue of poor functionality, adhesive hydrogel patches have emerged as an efficient bioactive multifunctional alternative. Hydrogels are three-dimensional, water-swellable, and polymeric materials closely resembling the native tissue architecture. The physicochemical properties of hydrogels can be modified easily, allowing them to be suitable for various biomedical applications. Moreover, adhesive properties can be imparted to hydrogels through physicochemical manipulations, making them ideal candidates for supplementing or replacing traditional sticking plaster. As a result, sticky hydrogel patches are widely used for transdermal drug delivery and have even found commercial purposes. Beyond transdermal delivery, such hydrogel patches have also found applications in cardiac therapy, cancer research, and biosensing, among other applications. In this mini-review, we critically discuss the challenges of fabricating multifunctional adhesive hydrogel patches. Furthermore, we introduce some of the chemical strategies involved with fabricating the patches. We also review their emerging biomedical applications. Finally, we explore their potential future in the flourishing field of tissue engineering and drug delivery

Indoor acids and bases.

Numerous acids and bases influence indoor air quality. The most abundant of these species are CO2 (acidic) and NH3 (basic), both emitted by building occupants. Other prominent inorganic acids are HNO3 , HONO, SO2 , H2 SO4 , HCl, and HOCl. Prominent organic acids include formic, acetic, and lactic; nicotine is a noteworthy organic base. Sources of N-, S-, and Cl-containing acids can include ventilation from outdoors, indoor combustion, consumer product use, and chemical reactions. Organic acids are commonly more abundant indoors than outdoors, with indoor sources including occupants, wood, and cooking. Beyond NH3 and nicotine, other noteworthy bases include inorganic and organic amines. Acids and bases partition indoors among the gas-phase, airborne particles, bulk water, and surfaces; relevant thermodynamic parameters governing the partitioning are the acid-dissociation constant (Ka ), Henry's law constant (KH ), and the octanol-air partition coefficient (Koa ). Condensed-phase water strongly influences the fate of indoor acids and bases and is also a medium for chemical interactions. Indoor surfaces can be large reservoirs of acids and bases. This extensive review of the state of knowledge establishes a foundation for future inquiry to better understand how acids and bases influence the suitability of indoor environments for occupants, cultural artifacts, and sensitive equipment

Analysis of Wireless Body-Centric Medical Sensors for Remote Healthcare

Aquesta tesi aborda el problema de trobar solucions confortables, de baixa potència i sense fils per aplicacions mèdiques. La tesi tracta els avantatges i les limitacions de tres tecnologies de comunicació diferents per la mesura de paràmetres del cos i mètodes per redissenyar sensors per avaluacions òptimes centrades en el cos. La tecnologia RFID es considera una de les solucions més influents per superar el problema del consum d'energia limitat, a causa de la presència de molts sensors connectats. També s'ha estudiat la tecnologia Bluetooth de baixa energia per resoldre els problemes de seguretat i la distància de lectura que, en general, representen el coll d'ampolla de RFID pels sensors de cos. Els dispositius analògics poden reduir dràsticament les necessitats d'energia a causa dels sensors i les comunicacions, considerant pocs elements i un mètode de transmissió simple. S'estudia un mètode de comunicació completament passiu, basat en FSS, que permet una distància de lectura raonable amb capacitats de detecció precises i confiables, que s'ha discutit en aquesta tesi. L'objectiu d'aquesta tesi és investigar múltiples tecnologies sense fils per dispositius portàtils per identificar solucions adequades per aplicacions particulars en el camp mèdic. El primer objectiu és demostrar la facilitat d'ús de les tecnologies econòmiques sense bateria com un indicador útil de paràmetres fisiopatològics mitjançant la investigació de les propietats de les etiquetes RFID. A més a més, s'ha abordat un aspecte més complex respecte a l'ús de petits components passius com sensors sense fils per trastorns del son. Per últim, un altre objectiu de la tesi és el desenvolupament d'un sistema completament autònom que utilitzi tecnologia BLE per obtenir propietats avançades mantenint baix tant el consum com el preuEsta tesis aborda el problema de encontrar soluciones confortables, inalámbricas y de baja potencia para aplicaciones médicas. La tesis discute las ventajas y limitaciones de tres tecnologías de comunicación diferentes para la medición en el cuerpo y los métodos para elegir y remodelar los sensores para evaluaciones óptimas centradas en el cuerpo. La tecnología RFID se considera una de las soluciones más influyentes para superar el consumo de energía limitado debido a la presencia de muchos sensores conectados. Además, la baja energía de Bluetooth se ha estudiado se ha estudiado la tecnologia Bluetooth de baja energia para resolver los problemas de seguridad y la distancia de lectura que, en general, representan el cuello de botella de la RFID para los sensores de cuerpo. Los dispositivos analógicos pueden reducir drásticamente las necesidades de energía debido a los sensores y las comunicaciones, considerando pocos elementos y un método de transmisión simple. Se estudia un método de comunicación completamente pasivo, basado en FSS, que permite una distancia de lectura razonable con capacidades de detección precisas y confiables, que se ha discutido en esta tesis. El objetivo de esta tesis es investigar múltiples tecnologías inalámbricas para dispositivos portátiles para identificar soluciones adecuadas para aplicaciones particulares en campos médicos. El primer objetivo es demostrar la facilidad de uso de las tecnologías económicas sin batería como un indicador útil de dichos parámetros fisiopatológicos mediante la investigación de las propiedades de las etiquetas RFID. Además, se ha abordado un aspecto más complejo con respecto al uso de pequeños componentes pasivos como sensores inalámbricos para enfermedades del sueño. Por último, un resultado de la tesis es desarrollar un sistema completamente autónomo que utilice la tecnología BLE para obtener propiedades avanzadas que mantengan la baja potencia y un precio bajo.This thesis addresses the problem of comfortable, low powered and, wireless solutions for specific body-worn sensing. The thesis discusses advantages and limitations of three different communication technologies for on body measurement and investigate methods to reshape sensors for optimum body-centric assessments. The RFID technology is considered one of the most influential solutions to overcome the limitated power consumption due to the presence of many sensors connected. Further, the Bluetooth low energy has been studied to solve security problems and reading distance that overall represent the bottleneck of the RFID for the body-worn sensors. Analog devices can drastically reduce the energy needs due to the sensors and the communications, considering few elements and a simple transmitting method. An entirely passive communication method, based on FSS is studied, enabling a reasonable reading distance with precise and reliable sensing capabilities, which has been discussed in this thesis. The objective of this thesis is to investigate multiple wireless technologies for wearable devices to identify suitable solutions for particular applications in medical fields. The first objective is to demonstrate the usability of the inexpensive battery-less technologies as a useful indicator of such a physio-pathological parameters by investigating the properties of the RFID tags. Furthermore, a more complex aspect regards the use of small passive components as wireless sensors for sleep diseases has been addressed. Lastly, an outcome of the thesis is to develop an entirely autonomous system using the BLE technology to obtain advanced properties keeping low power and a low price

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

Pharma-engineering of multifunctional microneedle array device for application in chronic pain

Chronic pain poses a major concern to modern medicine and is frequently undertreated, causing suffering and disability. Transdermal delivery is the pivot to which analgesic research in drug delivery has centralized especially with the confines of needle phobias and associated pain related to traditional injections, and the existing limitations associated with oral drug delivery. Highlighted within this thesis is the possibility of further developing transdermal drug delivery for chronic pain treatment using an Electro-Modulated Hydrogel- Microneedle array (EMHM) prototype device for the delivery of analgesic medicatio

Development of an insitu quantitative measurement system for stress hormones : towards open microfluidic system

Personalized health diagnostic and monitoring has gained serious attention in recent years and one area of interest is the analysis of hormones which indicate increased stress levels. Cortisol (known also as hydrocortisone) and cortisone are steroid hormone (also known as stress hormones) that plays an important role in the regulation of many physiological processes such as glucose levels, blood pressure, and carbohydrate metabolism and they are considered as a potent biomarker for post-traumatic stress. The determination of stress hormones represents a challenge because their secretion follows a circadian rhythm (all day cycle) and their secretion are dependent on environmental and behavioral triggers. As a result, there is a need to develop a system for cheaply and rapidly monitoring their levels using approaches such as lab-on-a-chip (LOC) which combine high selectivity and sensitivity to provide valuable health informatics, not just in human but in animals such as fish being bred in a fish farm.Selectivity in these devices can be achieved utilising an immunoassay approach taking advantage of the lock and key mechanism that is related to the antibody-antigen interaction. In this work, a new immunoassay method was developed to measure the stress hormones which involved the reproducible immobilization of cortisol and cortisone antibodies onto a tin-doped indium oxide (ITO) electrode. This was achieved by modifying the electrode in a two process step; the deposition of a nitro group onto the ITO electrode followed by the reduction of the nitro group to amino group using cyclic voltammetry. This approach enables a good orientation of the antibody on the surface. The antibodies were then immobilized using an EDC/Sulfo-NHS linkage. To enable electrochemical detection the antibodies were tagged with ferrocene to give a redox tag. When square wave voltammetry was utilised the method gave good limits of detection (LOD) of 1.03 pg ml-1 for cortisol and 0.68 pg ml-1 for cortisone.The methodology was carried out using biological sample including Zebrafish whole- body sample and artificial saliva and reliable results were obtained without the need for complex extraction procedure.The results of the analysis suggest that the proposed method has promise for the routine detection of stress hormones, which gives a good reason to detect cortisol and cortisone based on a chemiluminescence immunoassay. The antibodies were immobilised using the electrochemical method but then chemiluminescence detection was selected due to its high sensitivity and the simple instrumentation required. A static system was first constructed using a micropipette to add the chemiluminescence reagents with the use of a CCD camera and image J software to capture the chemiluminescence. To achieve chemiluminescence detection the ferrocene tag on the antibodies was first oxidised and then this acted as a catalyst for luminol and hydrogen peroxide chemiluminescence reaction. Optimum conditions were investigated and 20 mM luminol and 10 mM hydrogen peroxide were used with a 200 seconds exposure to the camera and an incubation time of 30 minutes. Using this approach limits of detection were obtained of 0.47 pg ml-1 and 0.34 pg ml-1 also R2 0.9912 and 0.9902 for cortisol and cortisone respectively. The method was also applied to Zebrafish and artificial saliva without analyte extraction and good results were obtained.Once the successful chemiluminescence immunoassays had been developed it could be incorporated into in situ measurement devices. In this work, an open microfluidic approach was investigated to overcome the problems of blockages, high back pressure and air bubbles seen in closed microfluidic systems. A superhydrophobic ITO electrode substrate was prepared depending on the lotus leaf effect of extreme water repellence by the deposition of dichlorodimethylsilane (DCDMS) onto the substrate, followed by dip coating the hydrophobised ITO electrode into fumed silica nanoparticle suspensions to increase the hydrophobicity. Superhydrophilic patterns were then produced using a mask and a UV/ozone lamp. The wetting properties were investigated in detail using a drop shape analysis system. Optimum conditions for the formation of a homogeneous coating were established giving the following results; fumed silica suspension concentration 4%, dip coating velocity 3.18 cm min-1, and sonication time of 10 minutes. The results obtained from fluorescence microscopy showed the capability of fluid to flow along the superhydrophilic pattern acting as an open microfluidic channel.Finally, the open microfluidic approach was combined with the immobilisation procedure. Although further work will be needed to optimise the system, chemiluminescence detection was achieved when the chemiluminescence reagents were passed through the open microfluidic channels over the immobilised antibodies.To conclude an electrochemical immobilization platform has been exploited to reproducibly immobilize the antibodies and develop a quantitative novel chemiluminescence assay for stress hormone analysis in combination with an open microfluidic device