Design and microfabrication of new automatic human blood sample collection and preparation devices

For self-sampling or collection of blood by health personal related to point-ofcare diagnostics in health rooms, it may often be necessary to perform automatic collection of blood samples. The most important operation that needs to be done when handling whole blood is to be able to combine automatic sample collection with optimal mixing of anticoagulation liquid and weak xatives. In particular before doing any transport of a sample or point-of-care nucleic acid diagnostics (POCNAD) it is very important to x the gene expression at the time of collection. It is also important to concentrate and separate out the white blood cells of interest from the whole blood before further detection. An automatic sample collection module with a microneedle array in combination with a micromixer is proposed for the blood collection in typical nurse or health rooms. An automatic human blood preparation module is also suggested that could be used for pre-mixing, concentration and lyses. Despite that the concept of microneedle has been intensively studied since several decades ago, the fabrication still remains very challenging. Major challenges concern the high aspect ratio of microneedle structure. In addition, the microneedles have to be su ciently strong to avoid fracture and cracks during practical implementation. The other challenge with small microchannel dimensions on a chip is the lack of turbulences (including fluids that operate with Reynolds number smaller than 2000). Hence a long mixing length is required for good mixing quality. This doctoral thesis focus on the following challenges: (i) design and optimize a continuous concentration and separation unit, (ii) optimize and improve the fabrication process of high aspect ratio metallic microneedle, (iii) develop and investigate the mixing performance of a passive planar micromixer with ellipse-like micropillars, (iv) integrate and demonstrate the pretreatment system. Article I reported the design and optimization of non-clogging counter-flow microconcentrator for enriching epidermoid cervical carcinoma cells. The counter-flow concentration unit with turbine blade-like micropillars were proposed in microconcentrator design. Due to the organization of these micropillar units the functionality cause a unique system of continuous concentration and separation. Due to the unusual geometrical-pro les and extraordinary micro fluidic performance, the cells blocking does not occur even at permeate entrances. The excellent concentration ratio of a fi nal microconcentrator was presented in both numerical and experimental results. Article II proposed a simple and low cost micromixer for laminar blood mixing. The design of micromixer unit was modifi ed from the counter-flow concentration units which mentioned in Article I. The e ciency of the splitting and recombination (SAR) micromixer was examined by theoretical methods, including finite element method and verifi ed by measurement results. Numerical results show that micromixer with ellipse-like micropillars have a well mixing status when its mixing effi ciency is higher than 80% as Re 6 1. Article III presented that the e ciency of the SAR micromixer for cell lysis. Some bacteria, especially gram-positive, may be diffi cult to lyse with conventional lysis bu er. If the cells are not properly lysed, the quality of the analysis results might suff er. With a splitting and recombination concept, homogeneous mixing can be obtained in short distance. Hence, the quality of the sample after lysis for further process (Nucleic Acid Purifi cation, Nucleic Acid Sequence Based Ampli fication) is also improved. The treatment in the SAR micromixer is comparable lysis by long ultrasound exposure. Hence, SAR micromixer proved to be a good alternative method for cell lysis. Moreover, SAR micromixer has the advantage that it can easily be integrated into an automatic system for lysis and sample treatment. Article IV investigated the mixing performance at the outlet of SAR micromixer. The outlet channel of SAR micromixer was split into four sub-channels. Absorbance testing was used to implement to evaluate the outlet concentration of four subchannels. The homogeneous of fluids are varied with the inlet velocities. Article V presented the optimized fabrication process of the template of extremely long microneedles for blood extraction. Backside lithography with a UVlight source was employed to build the high aspect ratio SU-8-based microneedle template. Some major challenges on fabrication process were also shown and discussed in this article. Article VI covers a total process chain from design, fabrication to performance evaluation of the hollow microneedle design. The contribution of this article is a highly applicable theoretical model for the microneedle geometry. The proposed model has been developed to predict the fracture forces. A good agreement was observed between the results obtained from analytical solution and practical measurements of fracture force

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

Magnetic components and microfluidics optimization on a Lab-on-a-chip platform

Tese de mestrado integrado, Engenharia Biomédica e Biofísica (Sinais e Imagens Médicas), Universidade de Lisboa, Faculdade de Ciências, 2017Desde 1934, quando Moldovan criou o primeiro instrumento que poderia ser descrito como um citómetro de fluxo, este equipamento tornou-se um importante componente em várias especialidades dentro do laboratório clínico para o diagnóstico, prognóstico e monitorização de um número incontável de doenças. Esta tecnologia biofísica suspende entidades biológicas num fluxo de fluido, sinalizando-as usando reconhecimento biomolecular, para depois as detetar através de um aparelho de detecção eletrónica. Com o crescimento das técnicas de fabricação de semicondutores e microfluídos, foram e continuam a ser feitas muitas tentativas de criar citómetros de fluxo do tipo Lab-on-a-Chip (LOC), o que certamente irá afastar os equipamentos usados hoje me dia nos laboratórios por equipamentos usados in situ de custo e tamanho reduzidos, portáteis e sem necessidade de pessoal especializado. Após uma revisão bibliográfica das técnicas e princípios de funcionamento dos equipamentos já existentes foi possível perceber que a utilização de partículas magnéticas (PM) pode ter várias vantagens quando comparadas com o uso convencional de deteção por fluorescência, removendo assim a necessidade de integrar e alinhar componentes ópticos, permitindo uma medição direta e a construção de um citómetro de fluxo LOC com preparação, separação e deteção de amostras totalmente magnético. No INESC-MN foi feito um protótipo que permite a deteção de um tipo de PMs em tempo real a velocidades da ordem de cm/s usando sensores magnetoresistivos integrados em canais microfluídicos mas a primeira demonstração desta técnica para aplicações de citómetro foi realizada através da detecção de células Kg1-a marcadas com PMs de 50 nm que passaram, através de um canal microfluídico, sobre 3 sensores magnetoresistivos demonstrando que, para amostras de elevada concentração, pode ter a mesma eficiência que um hemocitómetro, mas com menor erro. Tendo como ambição um dispositivo LOC capaz de contar várias entidades biológicas na mesma amostra, um módulo de contagem com vários canais paralelos é necessário. Nesse sentido, foi projetado um novo chip com 4 colunas separadas por 3 mm, cada uma com 7 sensores do tipo válvula de spin (SV) com uma área de deteção de 100x4 μm2 distanciados 150 μm uns dos outros. Os sensores são abordados individualmente por uma linha de corrente de alumínio de 300 nm e passivados com 300 nm de nitreto de silicio. Alinhados com as colunas de sensores, 4 canais de polydimethylsiloxane (PDMS) com uma secção de 20 μm de altura e 100 μm de largura foram irreversivelmente colados ao chip por ultravioleta-ozono (UVO) criando o canal onde a amostra irá fluir. Para que as PMs sinalizem a sua passagem é necessário colocá-las sob um campo magnético forte o suficiente para induzir a sua magnetização e para que, consequentemente, as PMs emanem um campo marginal significativo. Aproveitando a insensibilidade das SVs às componentes perpendiculares ao seu plano (xy), aplica-se um campo magnético nesse sentido (z) para magnetizar as partículas. As PMs ao passarem sobre o sensor geraram um sinal bipolar devido ao campo marginal criado pela sua magnetização perpendicular. Como é apresentado na simulação do sinal, a amplitude do mesmo depende apenas da altura da partícula em relação ao sensor e da magnetização das mesmas, idealmente, uma saturação da magnetização das partículas e o máximo de proximidade aos sensores geraria a maior amplitude possível. O campo magnético perpendicular foi criado usando um magnete de neodímio posicionado sob a placa de circuito impresso (PCB), onde o chip do citómetro é colado e as ligações entre o chip e a PCB soldadas por ultrassons com fio de alumínio. Na abordagem usada em Loureiro et al., 2011, um magnete de 20 mm x 10 mm x 1 mm foi simplesmente colado sob a PCB, mas devido aos campos magnéticos serem sempre fechados as componentes x e y criam desvios nas curvas de transferência dos sensores deixando apenas 1 ou 2 sensores de uma coluna do chip operacionais. Numa abordagem seguinte foi usado um magnete 20 mm x 20 mm x 3 mm distanciado 2 cm abaixo da PCB, isto tornou as curvas de transferência dos sensores adequadas para medição, mas fez com que a componente z do campo magnético não fosse grande o suficiente para que as PMs emanassem um campo magnético suficientemente forte. Percebendo as falhas de cada uma das configurações anteriores, foram feitas simulações do campo magnético que iria influenciar o chip originado por magnetes de vários tamanhos a várias distancias para perceber qual conseguiria fornecer uma maior área em que as componentes x e y fossem menores que 10 Oe e em que a componente z fosse de pelo menos 1 kOe. Através das simulações foi concluído que o magnete de 20 mm x 10 mm x 1 mm o mais próximo possível do chip seria a melhor solução, mas que um alinhamento preciso seria necessário. Para esse fim, foi fabricado numa fresadora um sistema de alinhamento em PMMA. Para que o alinhamento fosse o correto foram feitos 4 furos de alinhamento no sistema de PMMA e na PCB e para reduzir a distancia ao máximo foi feita uma bolsa na PCB da mesma área que o chip deixando a distancia do magnete aos sensores de 1 mm (0.3 mm de PCB + 0.7 mm de substrato de silício). Com isto, o alinhamento em x foi conseguido, mas para alinhar em y foi criado um trilho no sistema de PMMA onde o magnete pudesse deslizar, controlando-o pela rotação de um parafuso com passo de 0.5 mm. Para colocar o magnete na posição ideal, foi medida consecutivamente a curva de transferência do 4º sensor de uma das colunas, num campo magnético de -141 Oe a 141 Oe, até que este tivesse um campo de acoplamento efectivo (Hf) de aproximadamente 0 Oe, o que significa que a curva de transferência estaria perfeitamente centrada em zero e criaria um sinal bipolar perfeito. Após o alinhamento e posicionamento do magnete, todos os sensores foram caracterizados e, nesses resultados, podemos ver perfeitamente o efeito das componentes x e y do magnete. Com o lado longo do magnete paralelo ao lado longo das SVs e alinhado de forma que o Hf fosse o mais próximo de 0 Oe no 4º sensor de uma coluna, percebemos que a componente x (lado longo) do campo magnético criado pelo magnete tem efeitos na sensibilidade dos sensores fazendo com que esta caia à medida que nos afastamos do centro do magnete. Enquanto que a componente y tem efeitos sobre o Hf dos sensores tornando-o mais positivo à medida que medimos a 3ª, 2ª e 1ª linha de sensores e tornando-o mais negativo quando medimos a 5ª, 6ª e 7ª linha. São também apresentadas simulações dos canais microfluídicos para perceber como a velocidade das partículas afeta o sinal e qual a velocidade máxima permitida para que placa de aquisição eletrónica seja capaz de o detetar. Com estas conclusões, um novo chip foi desenhado e fabricado. Neste novo chip a distância entre as colunas de SVs foi reduzida para apenas 1 mm, o que obrigou também à alteração dos canais microfluídicos, ao tamanho do chip e da estrutura de PDMS. Também são apresentadas simulações que mostram que se um segundo magnete, alinhado com o primeiro, for colocado sobre os canais microfluídicos poderá melhorar a magnetização e a homogeneidade do campo, o que permitirá que os 4 canais tenham a mesma sensibilidade e um desvio padrão de Hf menor. Todos os antecedentes teóricos, os métodos de microfabricação e técnicas de caracterização usados são apresentados e descritos.The diagnosis, prognosis and monitoring of diseases serves for the only purpose of preserving and improving life. Being this the greatest objective of the human kind, since ever that efforts have been made to better our ways to do that. One of those, a very important component in several specialties within the clinical laboratory is the flow cytometer, a biophysical technology which uses biomolecular recognition to sort and count biological entities by suspending them in a stream of fluid and detecting them through an electronic detection apparatus. The improvement of the semiconductor and microfluidic fabrication techniques have created the chance to bring the expensive, specialized and bulky equipment out of the laboratories and generate new machines able of having the same efficiency but with smaller price, size, allowing portability and removing the need for specialized personnel. This is the concept behind the next generation of in pointof- care apparatus, the La-on-a-Chip (LOC). At INESC-MN it is understood the potential that magnetic particles (MP) have in a LOC flow cytometer and as such a real-time detection of single magnetic particles magnetoresistive based cytometer was prototyped. Demonstration of this technique for cytometer applications was accomplished by indicating that for high concentration samples it can have the same efficiency as the hemocytometer method but with lesser error. This thesis has as objective the optimization of the magnetic and microfluidic components of a LOC to allow the parallelization of measurements and enabling the real-time measurement of different particles at the same time. For this purpose, a bibliographic review of the theoretical backgrounds, of the fabrication and characterization techniques, of the different detecting principles and of the already existing magnetoresistive counting modules was made to get a deeper understanding of the optimization possibilities. The present work describes the above-mentioned platform for dynamic detection of magnetic labels with a magnetoresistive based flow cytometer, where a permanent magnet is used to magnetize the labels enabling them to trigger the sensor. Several simulations of the magnetic fields created by the permanent magnet and the microfluidic channels were done and analyzed in order to characterize the MPs signal, understand which would be the best positioning of these components and which fluid velocities would be in the range of the electronic read-out capabilities. This study led to the fabrication of a micromachined polymethylmethacrylate (PMMA) alignment system to correctly position the permanent magnet under the cytometer’s chip. This made the control over the magnet’s positioning more sensible and thus reducing the influence of its unwanted magnetic components on the chip. The approximation of the magnet to the chip enhanced the signal by optimizing the MPs magnetization and consequently the signal amplitude, the precise alignment corrected the sensors response by improving its sensitivity and removing them from saturation states. Through this new setup all the sensors in the chip became operational. Finally, using the several techniques of microfabrication also describe in this thesis, a new chip was designed and fabricated to improve even more the sensors sensitivity and consequently augment the number of the cytometer’s counting channels

Development of Facile Microfabrication Technologies for the Fabrication and Characterization of Multimodal Impedimetric, Plasmonic, and Electrophysiological Biosensors

The objective of this dissertation was to develop novel methods of patterning inorganic and organic materials, develop biocompatibility evaluations, and subsequently apply these methods toward developing biosensors and lab-on-a-chip devices, such as Interdigitated Electrodes (IDEs) and Microelectrode Arrays (MEAs) on non-traditional (such as nanostructured and plasmonic) polymer substrates or deploy these methods to enhance precision cellular placement on traditional (glass) MEA substrates. It was hypothesized that a combination of such facile microfabrication techniques and patterning technologies on traditional and non-traditional substrates would increase the sensitivity and selectivity of such sensor platforms by several orders of magnitude, and potentially introduce new modalities for cell-based biosensing. In order to demonstrate the biological functionality of these new IDEs and MEAs, a variety of cell cultures were used (cardiac, stem cell, and endothelial cells) to study the growth, proliferation, modes of increasing sensitivity and response to various compounds in vitro (outside the body)

Disposable Lab-on-Chip Systems for Biotechnological Screening

The main goal of this work was to develop different disposable Lab-on-Chip (LoC) systems for the application of biotechnological screening e.g. for bioprocess development through microorganisms or drug testing with human cell lines. Nowadays, microfluidics represents a highly promising field for the fabrication of microtools, as the increasing demand for screening data are difficult to meet with current platforms. This is mainly due to time and cost aspects as well as a limited amount of newly developed drugs. The ideal microfluidic platform for biotechnological screening should include three different groups of elements: (i) microbioreactors (MBR) in which cultivation takes place; (ii) auxiliary microfluidic systems (for transportation, filtration or mixing), and (iii) enzymatic biosensors for onchip analysis of substrate concentrations which are difficult to measure offline due to small available sample volumes. Within the scope of this work, various horizontally and vertically positioned MBR designs (resembling plug flow reactors, micro stir tanks or bubble columns) were developed, fabricated and successfully applied to the screening of different biological expression systems, such as yeast cells (S. cerevisiae), fungal spores (A. ochraceus) and primary human endothelial cells. Different integrated functional structures based on geometrical, optical or electrical elements allowed for online monitoring of various physical, chemical and biological process parameters during cultivation. In terms of the second group, passive and active microvalves, PZTand pneumatically actuated micropumps, passive filtration and mixing elements were produced. The third group comprised different types of enzymatic biosensors based on a hybrid detection principle (electrochemical-optical) and on different types of enzymatic responses. In general, the unique LoC setup (patterned element made of poly(dimethylsiloxane) and bonded to a glass substrate) allows an easy integration of systems into one monolithic LoC platform which are usually better suited for technically mature systems. Modular systems are advantageous for prototyping of new microfluidic applications. Therfore, an LoC construction kit was developed that offers a user friendly, standardized modular platform.Im Rahmen der Dissertation wurden verschiedene Einweg-Lab-on-Chip Systeme entwickelt, die beispielsweise bei biotechnologischen Parameterstudien von Mikroorganismen zur Bioprozesssteigerung oder von humanen Zelllinien zum Wirkstoffscreening Anwendung finden. Die Mikrofluidik ist ein vielversprechendes Forschungsgebiet für die Herstellung von kostengünstigen Mikrochips, womit der steigende Bedarf für Screening-Daten aufgrund von Vorteilen wie Zeit- und Kostenreduzierung erfüllt werden kann. Eine ideale mikrofluidische Plattform zum biotechnologischen Screenen sollte aus folgenden Gruppen bestehen: (i) dem Mikrobioreaktor zur Kultivierung, (ii) mikrofluidische Komponenten zum Transportieren, Filtrieren und Mischen von Suspensionen, und (iii) einem enzymatischen Biosensor für die on-Chip Analyse von Substratkonzentrationen. Innerhalb der Arbeit wurden diverse horizontal und vertikal positionierte Mikrobioreaktoren entwickelt, hergestellt und erfolgreich zum Screenen von unterschiedlichen biologischen Expressionssystemen (wie S. cerevisiae, A. ochraceus und humane Endothelzellen) angewendet. Die Integration von geometrischen, optischen und elektrischen Funktionselementen erlaubte eine online Überwachung von verschiedenen physikalischen, chemischen und biologischen Prozessparametern während der Kultivierung. Im Bereich der Gruppe (ii) wurden passive und aktive Mikoventile, PZT- und pneumatisch aktuierte Mikropumpen, Filtrations- und Mischkomponenten hergestellt und charakterisiert. Gruppe (iii) umfasste die Entwicklung eines enzymatischen Biosensors mit hybridem (elektrochemisch-optisch) Messumformer. Der einheitliche Chipaufbau aller Lab-on-Chip Systeme – bestehend aus einer Kombination von strukturiertem Polydimethylsiloxan und Glas – erlaubt das monolithische und modulare Zusammenschalten der Einzelsysteme zu der gewünschten Plattform. Da für erste Prototypen eine modulare Verschaltung zu bevorzugen ist, wurde ein Baukastensystem entwickelt, welches eine standardisierte und benutzerfreundliche Plattform für flexible Versuchsaufbauten bietet

Integrated lab-on-chip technology for zebrafish embryo sorting and larvae immobilization for drug discovery

The major current hurdle to widespread deployment of zebrafish embryos and larvae in large-scale drug discovery is the problem of enabling analytical platforms with high throughput. In order to spearhead drug discovery using zebrafish as a model, platforms need to determine pre-test sorting of organisms to ensure quality control and standardisation, and determine that their in-test positioning is suitable for high-content imaging with modules for flexible drug delivery. Manual procedures for sorting hundreds of embryos are very monotonous and therefore liable to significant analytical errors caused by operators’ fatigue. In this thesis, we present an innovative proof-of-concept design for a micromechanical large-particle in-flow sorter. This thesis investigated infra-red sensor detection and image acquisition and compared them for their ability to distinguish between viable and dead embryos. High-definition additive manufacturing systems for fabrication of 3D printed moulds of the type used in soft lithography were also explored. 3D printing using SLA provides a rapid microfabrication of the moulds with high definition and optical transparency, as is confirmed by both scanning electron microscopy and confocal microscopy. SLA technologies may be applied for the rapid and accurate fabrication of millifluidic devices that can trap millimetre-sized specimens such as living zebrafish larvae. We applied this new manufacturing method in a proof-of-concept prototype device capable of trapping and immobilising living zebrafish larvae for the purpose of recording heart rate variations in cardio-toxicity experiments. Static conventional culture plates limit the throughput data, and is not suitable for modern compound library screening, while currently available conventional microtiter well plates require manual pipetting, which is labour intensive and time consuming. This research offers promising avenues for the development of a miniaturised, automated system for handling and manipulating zebrafish embryos and larvae, using innovative microfluidic lab-on-chip (LOC) technologies and additive manufacturing technologies

Development, characterisation and evaluation of sugar glass microneedles

Biodegradable microneedles (MNs) are currently being developed to painlessly facilitate the effective permeation of therapeutic substances across the skin barrier. As sugar glasses are utilised in nature to protect proteins and other delicate structures upon dehydration, such materials may be an appropriate substrate for the preparation of biodegradable MNs. The aim of this work was to investigate for the first time the feasibility of preparing biodegradable MNs from sugar glasses and to test their potential utility for drug delivery applications. Solid sugar products were fabricated from 32 different solutions containing a range of individual sugars and binary sugar combinations, utilising a low temperature dehydration methodology. Subsequently, a novel vacuum-forming micromoulding methodology was developed and optimised to produce sugar glass microneedle (SGMN) arrays from silicon master structures. The sugar materials and MN structures were characterised using a variety of microscopic, thermal and x-ray diffraction analyses. The ability of SGMNs to puncture human skin was assessed in an in vitro skin model, whilst SGMN facilitated drug delivery was investigated using modified static Franz-type diffusion cells. A range of model substances including methylene blue (MB) dye, ibuprofen sodium (IBU), sulforhodamine B (SRB), FITC-BSA and β-galactosidase (β-gal) were incorporated within SGMN arrays. Furthermore, novel SGMN adhesive patches containing SRB within the backing only were fabricated using silicone and acrylate adhesives. Long-term stability of SGMN arrays was assessed under a range of differing storage conditions. Initial characterisation studies suggested that non-crystalline sugar material was formed from anhydrous trehalose and sucrose (75:25 %w/w) sugar solutions. This finding was critical to future SGMN fabrication and incorporation of model substances within the material. Process optimisation led to fabrication of SGMNs with strong morphological fidelity to master structures, which reliably penetrated human skin to facilitate diffusion of MB dye. Furthermore, SGMNs were shown to dissolve rapidly and completely in human skin and deliver MB, IBU, SRB and FITC-BSA to the deeper skin layers. Diffusion study data suggested that SGMN arrays incorporating a range of model substances facilitated permeation across skin in a bolus delivery manner. Additionally, it was found that SGMN adhesive patches were able to control permeation of SRB, a model hydrophilic compound. Sugar glasses containing β-gal were shown to stabilise enzyme functionality at approximately 40 % of initial activity over a 3 month period when stored under desiccation. Elevated humidity and temperature storage was detrimental to SGMN morphology, with 10 % relative humidity at 20 °C being optimal for MN preservation. Overall, this study suggests the utility of SGMNs for the stable incorporation and effective intra- or trans-dermal delivery of a range of model substances, including hydrophilic and macromolecular molecules. Furthermore, it was shown that a novel SGMN adhesive patch may provide the capability to control drug release across skin. Sugar glasses demonstrated a stabilising effect upon a functional protein cargo, although it appeared that storage conditions had a strong influence upon physical SGMN stability.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Monitoring the efficacy of aseptic sterilization processes by means of calorimetric and impedimetric sensing principles

Package sterilization is an essential step during aseptic packaging of food, pharmaceuticals or medical instruments to prevent microbiological contamination of the product. In food industries, the main objective is to produce consumer-safe and long-term stable food products. In recent years, the favored method to sterilize package material is by use of gaseous hydrogen peroxide (H2O2) at concentrations up to 10% v/v and elevated temperatures up to 300 °C. These process parameters enable a fast and effective, in chain sterilization of packages prior to filling with sterile products. Monitoring of this sensitive process is performed by predefined machine settings and laborious microbiological challenge tests, with earliest results after 72 hours. In previous works different sensors to monitor the packaging sterilization process have been developed, but till now there is no commercial system available to continuously monitor the final gas concentration or the microbial sterilization efficacy online within the package. In the present work, as a first approach the sensing principle of a calorimetric H2O2 gas sensor has been studied in more detail. The sensor is based on a differential set-up of one catalytically activated and one passivated temperature-sensing element. Surface characterizations have been performed to reveal the chemical reaction of H2O2 at the applied catalyst manganese(IV) oxide (MnO2). The surface characterization depicted a transition of the manganese oxidation state. Moreover, the treatment with H2O2 eliminates the polymeric layer on top of the catalyst, which has been applied as polymer matrix to attach the catalyst onto the sensing element. The calorimetric gas sensor has been further described by analytical expressions in order to evaluate the theoretical temperature rise. Thereby, different sensor scenarios (steady-state process, gas diffusion process and convective gas flow) have been described by the sensor's thermochemistry and physical transport mechanisms. These theoretical assumptions have been accompanied by surface and thermal characterizations of polymers applied as passivation materials. The characterizations demonstrate the suitability of the three investigated polymers (SU-8 photoresist, Teflon derivatives PFA and FEP), to act as a passivation against gaseous H2O2. As second approach of this work, a novel biosensor has been developed. This biosensor is based on interdigitated electrodes (IDE) on which a standardized test organism is immobilized. This test microorganism, spores of Bacillus atrophaeus, is commonly applied in industrial microbiological challenge tests to evaluate the efficacy of sterilization processes. Impedance measurements are applied to characterize the microbiological samples at the sensor surface before and after the gaseous H2O2 sterilization process. Thereby, a remaining change in impedance and phase has been observed. Numerical simulation tools have been employed to analyze the sensor signal, and to gather material parameters of the spores. Finally, the impedimetric and calorimetric sensor have been combined to serve as a miniaturized sensor system to analyze the efficacy of the gaseous sterilization process