No presente trabalho propomos a utilização de uma técnica refratométrica baseada na determinação do ângulo crítico para o desenvolvimento de um sensor de umidade relativa e, no mesmo escopo de aplicação, um medidor de vácuo primário. A técnica proposta tira vantagem da diferença de fase adquirida pelas componentes paralela e perpendicular de um feixe luminoso, linearmente polarizado, passando por reflexão interna, para produzir um laser de HeNe sintonizável, um polarizador, um prisma semicilíndrico de índice de refração conhecido fabricado em vidro tipo flint, um analisador, um mínimo de intensidade, facilmente detectável no perfil refletido correspondendo à posição do ângulo crítico. Desenvolvemos um estudo acerca dos principais aspectos teóricos envolvidos no fenômeno da reflexão total interna, onde realizamos algumas simulações buscando avaliar as variações da posição angular do ângulo crítico a partir de alterações no índice de refração. A montagem básica utilizada nos experimentos consiste de um CCD linear e de um computador, onde as informações coletadas pelo CCD foram tratadas por meio de um programa de aquisição de dados desenvolvido na plataforma LabVIEWTM. O programa empregado permite o acompanhamento das variações do perfil refletido da base do prisma ponto a ponto, ou seja, é possível acompanhar toda a dinâmica de evolução do índice de refração da amostra analisada em tempo real. Para confirmação da efetividade da técnica, realizamos medidas da variação do índice de refração de amostras gasosas em função da umidade relativa e da pressão. O sistema demonstrou sensibilidade suficiente para acompanhar mudanças da ordem de 10-5em unidades do índice de refração. / In the present work we propose the use of a refractometric technique based on the determination of the critical angle for the development of a relative humidity sensor and, in the same application scope, a primary vacuum gauge. The proposed technique takes advantage of the phase difference acquired by the parallel and perpendicular components of a, linearly polarized, light beam undergoing internal reflection, to produce an easily detectable intensity minimum in the reflected profile corresponding to the position of the critical angle. We develop a study about the main theoretical aspects involved in the total internal reflection phenomenon, where we perform some simulations aiming to evaluate the variations of the critical angle angular position from changes on the refractive index. The basic set up used in the experiments consist of a HeNe tunable laser, a polarizer, a semi-cylindrical prism with known refractive index made of flint glass type, a analyzer, a linear CCD and a computer, where the information collected by de CCD were treated by means of a data acquisition program developed on the LabVIEWTM platform. The used program allows the point-by-point monitoring of the changes of the profile reflected from the prism base, in other words, one can monitor all the evolution dynamics of the refractive index of the analyzed sample in real time. To confirm the effectiveness of the technique, we perform measurements of changes of the refractive index of gaseous samples as function of the relative humidity and the pressure. The system has shown enough sensitivity to track changes of the order of 10-5 in units of the index of refraction.

The diploma thesis is about designing device which monitors temperature and humidity. In the first part of thesis are explained basic terms, importance of key variables and on market offered products are described. After that the thesis describes device concept design with schematic designs. From designed schematics are described printed circuit board designs. Next part is about device commissioning and correction of errors caused by incorrect design. Last part is about program designing and device testing.

Ionic polymer-metal composites (IPMCs) are widely studied for their potential as electromechanical sensors and actuators. Bending of the IMPC depends on internal ion motion under an electric potential, and the addition of an ionic liquid and ionic self-assembled multilayer (ISAM) conductive network composite (CNC) strongly enhances bending and improves lifetime. Ion conducting polyelectrolytes poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) and Nafion® were incorporated into an ISAM CNC film with poly(allylamine hydrochloride) (PAH) and anionic gold nanoparticles actuators to further improve bending. CNC films were optimized for bending through pH adjustments in PAH and adding NaCl to the PAMPS and Nafion® solutions. PAMPS-containing actuators showed larger and faster bending than those containing Nafion® in the CNC. The IPMC actuator was also evaluated for its potential as a humidity sensor based on its relative humidity (RH) dependent steady-state current. The detection range is at least 10-80%RH, with 5%RH increment differentiation and likely better resolution. Effects of CNC presence and thickness were studied, in conjunction with ionic liquid at a range of RH values. A thin CNC (pH 4 PAH) produced the greatest current differentiation between RH values. The current's response speed to a large RH decrease was approximately 4 times faster than that of a fast commercial digital hygrometer. Additionally, the presence of a CNC and ionic liquid improved the current response time. These results indicate that an IPMC based humidity sensor using a CNC and ionic liquid is very promising and merits further study. / Master of Science

No description available.

Radio frequency identification (RFID) and sensing are two key technologies enabling the Internet of Things (IoT). Development of RFID tags augmented with sensing capabilities (RFID sensor tags) would allow a variety of new applications, leading to a new paradigm of the IoT. Chipless RFID sensor technology offers a low-cost solution by eliminating the need of an integrated circuit (IC) chip, and is hence highly desired for many applications. On the other hand, printing technologies have revolutionized the world of electronics, enabling cost-effective manufacturing of large-area and flexible electronics. By means of printing technologies, chipless RFID sensor tags could be made flexible and lightweight at a very low cost, lending themselves to the realization of ubiquitous intelligence in the IoT era. This thesis investigated three construction methods of printable chipless RFID humidity sensor tags, with focus on the incorporation of the sensing function. In the first method, wireless sensing based on backscatter modulation was separately realized by loading an antenna with a humidity-sensing resistor. An RFID sensor tag could then be constructed by combining the wireless sensor with a chipless RFID tag. In the second method, a chipless RFID sensor tag was built up by introducing a delay line between the antenna and the resistor. Based on time-domain reflectometry (TDR), the tag encoded ID in the delay time between its structural-mode and antenna-mode scattering pulse, and performed the sensing function by modulating the amplitude of the antenna-mode pulse. In both of the above methods, a resistive-type humidity-sensing material was required. Multi-walled carbon nanotubes (MWCNTs) presented themselves as promising candidate due to their outstanding electrical, structural and mechanical properties. MWCNTs functionalized (f-MWCNTs) by acid treatment demonstrated high sensitivity and fast response to relative humidity (RH), owing to the presence of carboxylic acid groups. The f-MWCNTs also exhibited superior mechanical flexibility, as their resistance and sensitivity remained almost stable under either tensile or compressive stress. Moreover, an inkjet printing process was developed for the f-MWCNTs starting from ink formulation to device fabrication. By applying the f-MWCNTs, a flexible humidity sensor based on backscatter modulation was thereby presented. The operating frequency range of the sensor was significantly enhanced by adjusting the parasitic capacitance in the f-MWCNTs resistor. A fully-printed time-coded chipless RFID humidity sensor tag was also demonstrated. In addition, a multi-parameter sensor based on TDR was proposed.The sensor concept was verified by theoretical analysis and circuit simulation. In the third method, frequency-spectrum signature was utilized considering its advantages such as coding capacity, miniaturization, and immunity to noise. As signal collision problem is inherently challenging in chipless RFID sensor systems, short-range identification and sensing applications are believed to embody the core values of the chipless RFID sensor technology. Therefore a chipless RFID humidity sensor tag based on near-field inductive coupling was proposed. The tag was composed of two planar inductor-capacitor (LC) resonators, one for identification, and the other one for sensing. Moreover, paper was proposed to serve as humidity-sensing substrate for the sensor resonator on accounts of its porous and absorptive features. Both inkjet paper and ordinary packaging paper were studied. A commercial UV-coated packaging paper was proven to be a viable and more robust alternative to expensive inkjet paper as substrate for inkjet-printed metal conductors. The LC resonators printed on paper substrates showed excellent sensitivity and reasonable response time to humidity in terms of resonant frequency. Particularly, the resonator printed on the UV-coated packaging paper exhibited the largest sensitivity from 20% to 70% RH, demonstrating the possibilities of directly printing the sensor tag on traditional packages to realize intelligent packaging at an ultra-low cost. / <p>QC 20150326</p>

This work explores the blending of e-textile technology with the porous electrode of polymer electrolyte membrane fuel cells (PEMFCs) and with smart wound patches to allow monitoring and in-situ diagnostics. This work includes contributions to understanding water transport and conductivity in the carbon cloth gas diffusion layer (GDL), and further developing thread-based relative humidity (RH) and temperature sensors, which can be sewn on a cloth GDL in PEMFCs. We also explore the application of the developed RH and temperature sensors in wearable biomonitoring. First, an experimental prototype is developed for evaluating water transport, thermal conductivity and electrical conductivity of carbon cloth GDLs under different hydrophobic coatings and compressions. Second, we demonstrate the addition of external threads to the carbon cloth GDL to (1) facilitate water transport and (2) measure local RH and temperature with a minimal impact on the physical, microstructural and transport properties of the GDL. We illustrate the roll-to-roll process for fabricating RH and temperature sensors by dip-coating commodity threads into a carbon nanotubes (CNTs) suspension. The thread-based sensors response to RH and temperature in the working environment of PEMFCs is investigated. As a proof-of-concept, the local temperature of carbon cloth GDL is monitored in an ex-situ experiment. Finally, we optimized the coating parameters (e.g. CNTs concentration, surfactant concentration and a number of dipping) for the thread-based sensors. The response of the thread-based sensors in room conditions is evaluated and shows a linear resistance decrease to temperature and a quadratic resistance increase to RH. We also evaluated the biocompatibility of the sensors by performing cell cytotoxicity and studying wound healing in an animal model. The novel thread-based sensors are not only applicable for textile electrochemical devices but also, show a promising future in wearable biomonitoring applications. / Graduate

La technologie d’identification radiofréquence (RFID) se décline aujourd’hui dans des milliers d’applications. Parmi elles nous pouvons citer les applications de gestion logistique des palettes/cartons dans les entrepôts industriels (RFID UHF) ainsi que l’identification des abonnés dans les réseaux de transports urbains (RFID HF). Depuis quelques années, des contributions scientifiques autour des technologies d’identification radiofréquence (RFID) avec un couplage capteur sont de plus en plus visibles. L’intérêt grandissant pour ce type de technologie s’appuie sur la possibilité d’une utilisation en masse de capteurs bon marchés pouvant être intégrés sur chaque objet. On parle alors d’objet connecté ou d’internet des objets (IoT). Dans cette thèse, nous nous focalisons sur l’étude et le développement d’un capteur RFID passif fonctionnant en bande UHF. Cette orientation technologique est dictée par l’application visée, l’agro-alimentaire, qui requiert des coûts de fabrication les plus faibles possibles et une distance de lecture supérieure au mètre. Pour l’élément sensible, nous utilisons un bio-polymère, plus précisément le gluten de blé dont les propriétés diélectriques en fonction de l’humidité relative ont été étudiées précédemment. Nous nous attachons à traiter toutes les problématiques liées à la communication entre un lecteur et un capteur RFID passif, l’objectif ultime de cette thèse étant de récupérer une information capteur à l’aide d’un lecteur RFID conventionnel respectant les standards du domaine et les directives radio en vigueur dans les différentes régions du monde. Pour valider cette étude, nous mettons en œuvre des capteurs-RFID pour réaliser un démonstrateur d’emballage « intelligent » permettant le suivi de la qualité des aliments. / Radio frequency identification (RFID) technology is available today in thousands of applications. Among them we can mention the logistics management applications pallets / cardboard in industrial warehouses (RFID UHF) and the identification of subscribers in urban transport networks (RFID HF). In recent years, scientific contributions around the radio frequency identification (RFID) technologies with a sensor coupling are increasingly visible. The growing interest in this type of development rely heavily on a mass use of inexpensive sensors that can be integrated on each object.It is calledconnected objects or Internet of Things (IoT). In this thesis, we focus on the study and development of a passive RFID sensor operating in UHF band. This technological orientation is dictated by the targeted application, the food industry, which requires the lowest possible manufacturing costs and a reading distance greater than one meter. For the sensitive element, we use a biopolymer, specifically wheat gluten whose dielectric properties as a function of relative humidity have been studied previously. We are committed to dealing with all the issues related to the communication between a reader and a passive RFID sensor, the ultimate objective of this thesis being to get a sensor information using a conventional RFID reader complying with the standards and the radio directives imposed in different regions of the world. To validate this study, we are implementing RFID sensors to create a smart packaging demonstrator for monitoring the quality of food.

Esta tese descreve o desenvolvimento e aplicação de sensores particulados (Parte A) e nanomecânicos (Parte B). Nanopartículas de poliestireno (PS) decoradas com Poli (etileno glicol), PEG, foram sintetizadas e caracterizadas antes e após adsorção do corante vermelho do Congo (VC). Colesterol oxidase (Chox), a principal enzima na oxidação do colesterol, foi imobilizada sobre PS/PEG e PS/PEG/VC para gerar sensores de colesterol. A bioconjugação entre VC e Chox permitiu respostas lineares para dosagem de colesterol HDL presente em amostras de sangue artificial. A lipase, uma hidrolase com larga aplicação científica e industrial, também foi imobilizada sobre PS/PEG e PS/PEG/VC. Os parâmetros cinéticos da hidrólise de p-nitrofenil butirato determinados para lipase livre e lipase imobilizada mostraram que sobre PS/PEG/VC a velocidade máxima de reação (Vmax) e número de renovação (kcat) aumentaram em comparação com os valores determinados para enzima livre. Lipase imobilizada sobre PS/PEG/VC pôde ser reutilizado por até sete vezes, perdendo um máximo de 10% ou 30% da atividade enzimática original a 40 °C ou 25 °C, respectivamente. Estes efeitos foram atribuídos à bioconjugação entre lipase e VC. Os comportamentos catalíticos da lipase e da Chox na ausência e na presença de grafeno (G) ou grafeno oxidado (GO) foram sistematicamente investigados. Na presença de G, ambas enzimas apresentaram valores de Vmax e de kcat superiores aos das enzimas livres. Já na presença de GO, Chox não apresenteou atividade e lipase apresentou Vmax e de kcat superiores aos da enzima livre. Estes resultados foram atribuídos à bioconjugação com as partículas de G e GO e grupos hidrofílicos presentes no plano basal de GO. Sensores nanomecânicos foram desenvolvidos a partir de microcantileveres (MC). Respostas nanomecânicas frente à variação de umidade relativa do meio foram detectadas utilizando filmes finos de Poli (hidroxietil metacrilato), PHEMA, com três diferentes massas molares médias depositados sobre MC de silício puros, um substrato hidrofílico, e sobre MC revestidos com PS, um substrato hidrofóbico. Os resultados demonstraram que as respostas nanomecânicas dependem não só do tamanho de cadeia de PHEMA, mas também da camada de água interfacial entre PHEMA e MC. Transdução nanomecânica foi usada para detectar e dosar a presença do biomarcador antígeno carcinoembrionário (CEA) presente em amostras de soro. CEA é um biomarcador de interesse clínico-diagnóstico para acompanhamento e prognóstico de câncer de cólon. O biomarcador é primeiro reconhecido pelo anticorpo (MAb 3C1) ancorado a uma nanopartícula de ouro, e posteriormente reconhecido pelo anticorpo (MAb 3C6) ancorado em um MC de silício, o qual serve como um ressonador mecânico de massa de nanopartículas de ouro capturadas. O biosensor desenvolvido é capaz de dosar CEA sérico em concentrações traços, correspondente a 1,0 10-16 g ml-1. / This thesis reports the development and application of particulate (Part A) and nanomechanics sensors (Part B). Poly (ethylene glycol), PEG, decorated polystyrene (PS) nanoparticles were synthesized and characterized before and after adsorption of the dye Congo red (CR). Cholesterol oxidase (Chox), the key enzyme in the oxidation of cholesterol, was immobilized onto PS/PEG and PS/PEG/CR particles for generating cholesterol sensors. The bioconjugation between CR and Chox allowed linear responses for HDL cholesterol content in artificial blood samples. Lipase, a hydrolase with large scientific and industrial applications, was also immobilized onto PS/PEG and PS/PEG/VC nanoparticles. The kinetic parameters of the hydrolysis of p-nitrophenyl butyrate were determined for free lipase and immobilized onto PS/PEG/CR particles. The results showed that maximum reaction velocity (Vmax) and catalytic efficiency (kcat) increased compared to the values determined for the free enzyme. Lipase immobilized onto PS/PEG/CR particles could be recycled seven times, losing maximum 10% or 30% of the original enzymatic activity at 40 °C or 25 °C, respectively. These effects were attributed to bioconjugation between lipase and CR. Catalytic behavior of lipase and Chox in the absence and in the presence of graphene (G) or graphene oxide (GO) was systematically investigated. In the presence of G, both enzymes showed Vmax and kcat values higher than free enzymes. On the other hand, ChOx was inactive and the interactions between GO and lipase showed Vmax and kcat values higher than those of the free enzyme. These results were attributed to bioconjugation of G and GO particles and hydrophilic groups present in the basal plane of GO. Nanomechanical sensors were developed from microcantilevers (MC). Nanomechanical answers against the relative humidity variation of the medium were detected using thin films of poly (hydroxyethyl methacrylate), PHEMA, with three different average molecular masses deposid onto bare silicon microcantilevers, a hydrophilic substrate, and onto polystyrene (PS) coated microcantilevers, which is a hydrophobic substrate. The results found in the present study demonstrate that the micromechanical responses observed are related not only to the polymer molecular weight, but also to the polymer-interface phenomena and environment-polymer interface. Nanomechanics transductions were used to dose and detect the presence of carcinoembryonic antigen in serum samples. CEA is a biomarker of clinical diagnostic interest for monitoring and prognose of colon cancer. Biomarker is first recognized by a surface-anchored antibody to a gold nanoparticle (MAB 3C1) and later recognized by a surface-anchored antibody to a silicon MC (MAB 3C6), that acts as a mechanical resonator for \'weighing\' the mass of the captured nanoparticles. The biosensor developed is able to dose serum CEA in trace concentrations, corresponding to 1.0 10-16 g ml-1.

Esta tese descreve o desenvolvimento e aplicação de sensores particulados (Parte A) e nanomecânicos (Parte B). Nanopartículas de poliestireno (PS) decoradas com Poli (etileno glicol), PEG, foram sintetizadas e caracterizadas antes e após adsorção do corante vermelho do Congo (VC). Colesterol oxidase (Chox), a principal enzima na oxidação do colesterol, foi imobilizada sobre PS/PEG e PS/PEG/VC para gerar sensores de colesterol. A bioconjugação entre VC e Chox permitiu respostas lineares para dosagem de colesterol HDL presente em amostras de sangue artificial. A lipase, uma hidrolase com larga aplicação científica e industrial, também foi imobilizada sobre PS/PEG e PS/PEG/VC. Os parâmetros cinéticos da hidrólise de p-nitrofenil butirato determinados para lipase livre e lipase imobilizada mostraram que sobre PS/PEG/VC a velocidade máxima de reação (Vmax) e número de renovação (kcat) aumentaram em comparação com os valores determinados para enzima livre. Lipase imobilizada sobre PS/PEG/VC pôde ser reutilizado por até sete vezes, perdendo um máximo de 10% ou 30% da atividade enzimática original a 40 °C ou 25 °C, respectivamente. Estes efeitos foram atribuídos à bioconjugação entre lipase e VC. Os comportamentos catalíticos da lipase e da Chox na ausência e na presença de grafeno (G) ou grafeno oxidado (GO) foram sistematicamente investigados. Na presença de G, ambas enzimas apresentaram valores de Vmax e de kcat superiores aos das enzimas livres. Já na presença de GO, Chox não apresenteou atividade e lipase apresentou Vmax e de kcat superiores aos da enzima livre. Estes resultados foram atribuídos à bioconjugação com as partículas de G e GO e grupos hidrofílicos presentes no plano basal de GO. Sensores nanomecânicos foram desenvolvidos a partir de microcantileveres (MC). Respostas nanomecânicas frente à variação de umidade relativa do meio foram detectadas utilizando filmes finos de Poli (hidroxietil metacrilato), PHEMA, com três diferentes massas molares médias depositados sobre MC de silício puros, um substrato hidrofílico, e sobre MC revestidos com PS, um substrato hidrofóbico. Os resultados demonstraram que as respostas nanomecânicas dependem não só do tamanho de cadeia de PHEMA, mas também da camada de água interfacial entre PHEMA e MC. Transdução nanomecânica foi usada para detectar e dosar a presença do biomarcador antígeno carcinoembrionário (CEA) presente em amostras de soro. CEA é um biomarcador de interesse clínico-diagnóstico para acompanhamento e prognóstico de câncer de cólon. O biomarcador é primeiro reconhecido pelo anticorpo (MAb 3C1) ancorado a uma nanopartícula de ouro, e posteriormente reconhecido pelo anticorpo (MAb 3C6) ancorado em um MC de silício, o qual serve como um ressonador mecânico de massa de nanopartículas de ouro capturadas. O biosensor desenvolvido é capaz de dosar CEA sérico em concentrações traços, correspondente a 1,0 10-16 g ml-1. / This thesis reports the development and application of particulate (Part A) and nanomechanics sensors (Part B). Poly (ethylene glycol), PEG, decorated polystyrene (PS) nanoparticles were synthesized and characterized before and after adsorption of the dye Congo red (CR). Cholesterol oxidase (Chox), the key enzyme in the oxidation of cholesterol, was immobilized onto PS/PEG and PS/PEG/CR particles for generating cholesterol sensors. The bioconjugation between CR and Chox allowed linear responses for HDL cholesterol content in artificial blood samples. Lipase, a hydrolase with large scientific and industrial applications, was also immobilized onto PS/PEG and PS/PEG/VC nanoparticles. The kinetic parameters of the hydrolysis of p-nitrophenyl butyrate were determined for free lipase and immobilized onto PS/PEG/CR particles. The results showed that maximum reaction velocity (Vmax) and catalytic efficiency (kcat) increased compared to the values determined for the free enzyme. Lipase immobilized onto PS/PEG/CR particles could be recycled seven times, losing maximum 10% or 30% of the original enzymatic activity at 40 °C or 25 °C, respectively. These effects were attributed to bioconjugation between lipase and CR. Catalytic behavior of lipase and Chox in the absence and in the presence of graphene (G) or graphene oxide (GO) was systematically investigated. In the presence of G, both enzymes showed Vmax and kcat values higher than free enzymes. On the other hand, ChOx was inactive and the interactions between GO and lipase showed Vmax and kcat values higher than those of the free enzyme. These results were attributed to bioconjugation of G and GO particles and hydrophilic groups present in the basal plane of GO. Nanomechanical sensors were developed from microcantilevers (MC). Nanomechanical answers against the relative humidity variation of the medium were detected using thin films of poly (hydroxyethyl methacrylate), PHEMA, with three different average molecular masses deposid onto bare silicon microcantilevers, a hydrophilic substrate, and onto polystyrene (PS) coated microcantilevers, which is a hydrophobic substrate. The results found in the present study demonstrate that the micromechanical responses observed are related not only to the polymer molecular weight, but also to the polymer-interface phenomena and environment-polymer interface. Nanomechanics transductions were used to dose and detect the presence of carcinoembryonic antigen in serum samples. CEA is a biomarker of clinical diagnostic interest for monitoring and prognose of colon cancer. Biomarker is first recognized by a surface-anchored antibody to a gold nanoparticle (MAB 3C1) and later recognized by a surface-anchored antibody to a silicon MC (MAB 3C6), that acts as a mechanical resonator for \'weighing\' the mass of the captured nanoparticles. The biosensor developed is able to dose serum CEA in trace concentrations, corresponding to 1.0 10-16 g ml-1.

Rotary air-to-air energy exchangers (also called energy wheels) transfer both heat and moisture between supply and exhaust airstreams in buildings. In this thesis, it is hypothesized that the transient step response characteristics of an energy wheel are uniquely related to the steady-state cyclic response of the wheel. The primary objective of this research is to study the transient response of a humidity/temperature sensor and measure energy wheel performance with a new test procedure that uses only transient response characteristics. In this thesis, the transient characteristics of a humidity/temperature sensor and an energy wheel to a step change in relative humidity and temperature are investigated through two types of measurements. One test uses a small airflow, at controlled temperature and humidity conditions, passing through a small section of a porous wheel while measuring the outlet conditions after the inlet conditions are suddenly changed. For a step input, it is shown that the outlet humidity/temperature sensor data correlate with an exponential function with two time constants. Since the transient response characteristics of the humidity/temperature sensor must be known to predict the response of the wheel alone, a second test is required that is similar to the first test except that the wheel is removed. This test is used to obtain the transient response of the sensor alone. Data from these tests show that both the sensor and the sensor plus wheel have two sets of two time constants. An analysis is presented to determine the transient response of the wheel alone using the correlated properties of the sensor alone and the sensor with a wheel upstream. The challenge undertaken in this research was the development of a more flexible, lower cost test facility than that presented in ASHRAE Standard 84-1991(Method of Testing Air-to-Air Heat Exchangers). In future work, this new laboratory experimental test facility should be adapted to test most types of energy wheels. The configuration allows a wide range of mass flow rates, inlet supply air temperatures and relative humidities. Uncertainty analysis is used for each transient test for the sensors and air-to-air energy wheels to specify the sensor and wheel plus sensor characteristics. This uncertainty analysis shows that accurate sensor calibration under equilibrium conditions and the start time for the humidity sensor step change is crucial to achieve low uncertainties in the transient behaviour of sensor and energy wheels. Knowing the uncertainty in the characteristics of the sensors and the wheel plus sensors the uncertainty in the transient response of the wheel alone is predicted. The first time constant of the humidity sensor is found to be about 3 seconds, while the second time constant is found to be about 100 seconds. It is found that the predicted response of the wheel alone gives time constants that are about 6 seconds and 140 seconds. Other researchers can use this information presented in this thesis to estimate the effectiveness of an energy wheel.