New type of microengine using internal combustion of hydrogen and oxygen

Microsystems become part of everyday life but their application is restricted by lack of strong and fast motors (actuators) converting energy into motion. For example, widespread internal combustion engines cannot be scaled down because combustion reactions are quenched in a small space. Here we present an actuator with the dimensions 100x100x5 um^3 that is using internal combustion of hydrogen and oxygen as part of its working cycle. Water electrolysis driven by short voltage pulses creates an extra pressure of 0.5-4 bar for a time of 100-400 us in a chamber closed by a flexible membrane. When the pulses are switched off this pressure is released even faster allowing production of mechanical work in short cycles. We provide arguments that this unexpectedly fast pressure decrease is due to spontaneous combustion of the gases in the chamber. This actuator is the first step to truly microscopic combustion engines.Comment: Paper and Supplementary Information (to appear in Scientific Reports

Programmable graphene-based microfluidic sensor for DNA detection

This study presents the development of a lab-on-a-chip (LoC) by integrating a graphene field-effect transistor (FET) chip with a programmable microfluidic device for DNA detection. The real-time biochemical events on the graphene FET chip were monitored through Dirac voltage shift data from the portable graphene curve reader with changes dependent on the fluidic flow into the sensing interface by a fully automated programmable microfluidic system. High sensitivity with high reliability can be obtained with a nine-graphene sensor layout on a single chip. The portable graphene curve reader also provides a tunable electrical parameter setup and straightforward data acquisition. Fluidic control was performed through a multi-position valve, allowing sequential commands for liquid injection into the polydimethylsiloxane (PDMS) flow cell mounted on the sensing chip. The flow cell design with impinging jet geometry and the microfluidic system packaging offer high precision and portability as a less laborious and low-cost sensing setup. The merged system allows for various functionalities, including probe DNA (pDNA) immobilization, a blocking step, and DNA hybridization with stable signal output autonomously, even in a long-run experimental setup. As a DNA sensor, the proposed prototype has demonstrated a high sensitivity of ~44 mV/decade of target DNA concentration, with an outstanding limit of detection (LoD) of ~0.642 aM, making it one of the most sensitive sensors reported up to date. The programmable device has demonstrated essential versatilities for biomolecular detection in a fully portable and automated platform.This research is supported by PORTGRAPHE-Control of Port and Douro Wines authenticity using graphene DNA sensors project co-funded by Fundação para a Ciência e a Tecnologia (FCT) Portugal (PTDC/BIA-MOL/31069/2017) and the ERDF through COMPETE2020 (POCI-01–0145-FEDER-031069). One of the authors (Telma Domingues) acknowledges a Ph.D. grant from Fundação para a Ciência e a Tecnologia (FCT) Portugal (SFRH/BD/08181/2020). FCT partially supported University of Minho´s research in the Strategic Funding UIDB/04650/2020

Development of a Stand-alone Microfluidic Device

Microfluidics, also referred to as lab-on-a-chip (LOC), is an emerging technology in which fluids can be precisely manipulated using micro-scale devices. In this work, we designed a stand-alone LOC system that includes a self-powered pump, an optical fiber-based flow detection sensor, and smartphone-based imaging platform. The designed device aims to combine multiple physical concepts into one, integrated, self-sufficient, and modular chip-based system. The team developed both fundamental understandings and hands-on experience on microfluidic systems, while the designs show great potential for a fully integrated device. Future work can utilize the methods developed in this work to fabricate and test alternate designs for a working and commercially producible LOC device

LTCC packaging for Lab-on-a-chip application

LTCC -pakkaus Lab-on-a-chip -sovellukseen. Tiivistelmä. Tässä työssä suunniteltiin, valmistettiin ja testattiin uusi pakkaustekniikka ”Lab-on-a-chip” (LOC) -sovellukseen. Pakkaus tehtiin pii-mikrosirulle, jolla voidaan mitata solujen kiinnittymistä sirun pintaan solujen elinkelpoisuuden indikaattorina. Luotettavuustestaukset tehtiin daisy-chain -resistanssimittauksilla solunkasvatusolosuhteissa. Lisäksi työssä selvitettiin LTCC- ja ”Lab-on-a-chip” -teknologioiden perusteet teoreettiselta pohjalta. Mikrosirun pakkauksessa käytettiin joustavaa LTCC-teknologiaa. Sähköisiin kontakteihin ja niiden suojauksiin käytettiin sekä johtavia että eristäviä epoksi-liimoja. LOC-sovelluksiin on tärkeää kehittää uusia pakkausmenetelmiä jotta näiden laitteiden kaikki ominaisuudet saadaan toimimaan luotettavasti. Pakkaus testattiin samoissa olosuhteissa missä sitä tullaan käyttämään ja pakkaus kesti kaikki nämä haasteet. Lisäksi esitetty valmistusprosessi on sellainen, että sitä voidaan käyttää myös muihin ”Lab-on-a-chip” -sovelluksiin.Abstract. This work presents design, manufacturing and testing of new packaging method for Lab-on-a-chip (LOC) application. Packaging was made for silicon microchip which can measure cell adhesion on chips surface as indication of cell viability. Reliability testing was done with daisy-chain resistance measurement in real conditions. Moreover basic theory of LTCC and Lab-on-a-chip technology is presented. Resilient LTCC technology was used for packaging material and conductive/insulating epoxies were applied for electrical contacts and barriers against the environment. It is fundamentally important to develop new packaging methods for LOC applications, so all the properties can be utilized reliably. Packaging was tested under the cell growth conditions and the package showed to withstand all these challenges. Moreover the presented packaging method is possible to use also in other Lab-on-a-chip applications

Analysis of relevant technical issues and deficiencies of the existing sensors and related initiatives currently set and working in marine environment. New generation technologies for cost-effective sensors

The last decade has seen significant growth in the field of sensor networks, which are currently collecting large amounts of environmental data. This data needs to be collected, processed, stored and made available for analysis and interpretation in a manner which is meaningful and accessible to end users and stakeholders with a range of requirements, including government agencies, environmental agencies, the research community, industry users and the public. The COMMONSENSE project aims to develop and provide cost-effective, multi-functional innovative sensors to perform reliable in-situ measurements in the marine environment. The sensors will be easily usable across several platforms, and will focus on key parameters including eutrophication, heavy metal contaminants, marine litter (microplastics) and underwater noise descriptors of the MSFD. The aims of Tasks 2.1 and 2.2 which comprise the work of this deliverable are: • To obtain a comprehensive understanding and an up-to-date state of the art of existing sensors. • To provide a working basis on “new generation” technologies in order to develop cost-effective sensors suitable for large-scale production. This deliverable will consist of an analysis of state-of-the-art solutions for the different sensors and data platforms related with COMMONSENSE project. An analysis of relevant technical issues and deficiencies of existing sensors and related initiatives currently set and working in marine environment will be performed. Existing solutions will be studied to determine the main limitations to be considered during novel sensor developments in further WP’s. Objectives & Rationale The objectives of deliverable 2.1 are: • To create a solid and robust basis for finding cheaper and innovative ways of gathering data. This is preparatory for the activities in other WPs: for WP4 (Transversal Sensor development and Sensor Integration), for WP(5-8) (Novel Sensors) to develop cost-effective sensors suitable for large-scale production, reducing costs of data collection (compared to commercially available sensors), increasing data access availability for WP9 (Field testing) when the deployment of new sensors will be drawn and then realized

Fabrication and Flow Dynamics Analysis of Micromixer for Lab-on-a-Chip Devices

The miniaturized systems designed for lab-on-a-chip (LOC) technologies are generally implemented with a micro-scale mixer to provide intimate contact between the reagent molecules for interactions and chemical reactions. The exponential increase of research in microfabrication and microfluidic applications highlights the importance of understanding the theory and mechanism that governs mixing at the microscale level. In this study, the fabrication of an active and passive micromixer was discussed. The optimized state of art soft lithography and 3D printing was used as a microfabrication technique. The challenges at different fabrication steps were presented along with the modifications. Microelectrodes were integrated with the active microfluidic mixer to create an electrokinetic effect. The fluid flow field inside the micromixerwas characterized by the Micro Particulate Image Velocimetry (Micro-PIV) system. Besides, numerical simulations were performed on 2D and 3D micromixers. Finally, results obtained in experiment and numerical simulations were analyzed to get a better understanding of the micromixer design

Thermocapillary actuation of droplets on chemically patterned surfaces by programmable microheater arrays

We have designed a microfluidic device for the actuation of liquid droplets or continuous streams on a solid surface by means of integrated microheater arrays. The microheaters provide control of the surface temperature distribution with high spatial resolution. These temperature gradients locally alter the surface tension along droplets and thin films thus propelling the liquid toward the colder regions. In combination with liquophilic and liquophobic chemical surface patterning, this device can be used as a logistic platform for the parallel and automated routing, mixing and reacting of a multitude of liquid samples, including alkanes, poly(ethylene glycol) and water

Microfluidic devices for high-throughput plant phenotyping and bioenergy harvesting from microbes and living plants

Microfluidics and micro/nanofabrication techniques provide powerful technological platforms to develop miniature bioassay devices for studying cellular and multicellular organisms. Microfluidic devices have many advantages over traditional counterparts, including good throughput due to parallel experiments, low infrastructural cost, fast reaction, reduced consumption of agent and reagent, and avoidance of contamination. This thesis is focused on the development of a microfluidic toolkit with several miniature devices to tackle important problems that the fields of plant phenotyping and bioenergy harvesting are facing. The ultimate goal of this research is to realize high-throughput screening methods for studying environment-genomics of plants through phenomics, and understanding microbial and plant metabolisms that contribute to harvesting bioenergy from microbes and living plants in different environments. First, we develop vertical microfluidic plant chips and miniature greenhouses for high throughput phenotyping of Arabidopsis plants. The vertical design allows for gravitropic growth of multiple plants and continuous monitoring of seed germination and plant development at both the whole-plant and cellular levels. An automatic seed trapping method is developed to facilitate seed loading process. Also, electrospun nanofibrous membranes are incorporated with a seed germination chip to obtain a set of incubation temperatures on the device. Furthermore, miniature greenhouses are designed to house the plant and seed chips and to flexibly change temperature and light conditions for high-throughput plant phenotyping on a multi-scale level. Second, to screen bacteria and mutants for elucidating mechanisms of electricity generation, we develop two types of miniature microbial fuel cells (µMFCs) using conductive poly(3,4-ethylenedioxythiophene) nanofibers and porous graphene foam (GF) as three-dimensional (3D) anode materials. It is demonstrated that in the nanofiber-based µMFC, the nanofibers are suitable for rapid electron transfer and Shewanella oneidensis can fully colonize the interior region of the nanofibers. The GF-based µMFC is featured with a porous anolyte chamber formed by embedding a GF anode inside a microchannel. The interconnected pores of the GF provide 3D scaffolds favorable for cell attachment, inoculation and colonization, and more importantly, allow flowing nutritional and bacterial media throughout the anode with minimal waste. Therefore, the nutrients in bio-convertible substrates can be efficiently used by microbes for sustainable production of electrons. Last, we develop a first miniature plant-MFC or µPMFC device as a technological interface to study bioenergy harvesting from microbes and living plants. A pilot research is conducted to create the µPMFC device by sandwiching a hydrophilic semi-permeable membrane between a µMFC and a plant growth chamber. Mass transport of carbon-containing organic exudates from the plant roots to the µMFC is quantified. This work represents an important step towards screening plants, microbes, and their mutants to maximize energy generation of PMFCs

Surface and Structural Engineering of Ionovoltaic Device for Energy Harvesting and Sensing Applications

학위논문 (박사)-- 서울대학교 대학원 : 융합과학기술대학원 융합과학부(나노융합전공), 2019. 2. 김연상.최근 Ionovoltaic 변환기라 명명된, 액체와 고체 표면의 접촉에서 전기가 발생하는 현상을 이용한 전기 변환 장치에 관한 연구가 많은 관심을 받고 있다. 신재생 친환경 에너지 발전 장치에 관한 필요성이 커지고 수용액 기반에서 능동적으로 작동 할 수 있는 다양한 센서에 관한 요구가 꾸준히 증가하는 가운데, ionovoltaic 소자는 이러한 요구를 충족 시킬 수 있는 능동형 장치로서 주목받고 있다. 하지만 ionovoltaic 소자를 에너지 발전 소자와 능동적 센서로 실질적 활용과 적용을 하기에는 출력 에너지 밀도가 낮고, 공정이 복잡하다. 더욱이 충분히 밝혀지지 않은 소자의 구동 원리와 소자의 획일적인 재료 및 구조 연구는 소자의 다양한 활용 발전을 가로막고 있다. 여기, 이 학위 연구는 ionovoltaic 장치의 (i) 표면 개질과 (ii) 구조 공정 개선, 두 가지 연구를 통해 계면에서의 이온거동에 의한 전기 발생 현상을 보다 명확히 밝히며 이를 통해 센서와 에너지 수확장치로서의 폭 넓은 활용을 다룬다. 첫째, 기존에 사용되었던 불소 기반의 획일적인 소수성 표면 물질을 벗어나 표면 개질을 통한 새로운 전기적 특성을 갖는 소수성 표면 공정을 ionovoltaic 전환 소자에 적용하여 액체와 고체 계면에서의 이온 거동을 이용한 다양한 센싱 어플리케이션에 적용하였다. 음의 표면전위를 갖는 소수성 표면의 변환기와 양의 표면전위를 갖는 소수성 표면의 변환기를 개발하여 비교 분석 하였으며 이온 거동에 의한 전기신호 반전 효과를 처음으로 확인 하였다. 뿐만 아니라, 산, 염기에 민감한 표면 특성을 활용하여 pH 센서 및 요소(urea) 센서로서 활용성을 검증하였다. 둘째, 기존에 사용되었던 2 전극 시스템의 획일적인 소자의 구조를 탈피하고 새로운 형태의 소자 구조 공정을 통해 액체와 고체 표면의 접촉이 전기신호로 변환되는 원리 파악과 센싱 및 에너지 수확장치로서의 적용 가능성을 제시하였다. 소자의 전체적인 구조 공정과 전극 연구를 통해서 전기 신호의 발생 지속시간을 조절 할 수 있었으며 에너지밀도를 높일 수 있었다. 뿐만 아니라 투명하면서도 전기를 발생시킬 수 있는 고저항 ITO 전극 개발을 통해 건물이나 자동차의 외관 및 창문에 활용 될 수 있는 에너지 수확장치를 개발하여 ionovoltaic 장치의 폭넓은 활용가능성을 제시하였다.Recently, there has been a lot of interest in the research on the transducers using the phenomenon of electricity generation in the contact between the liquid and solid surface. In particular, transducers using EDL (electrical double layer) modulations, which named as ionovoltaic transducers are attracting attention because of their advantages in eco-friendly, simple drive systems and self-powered characteristics. With the growing need for renewable and eco-friendly energy generation devices and the increasing demand for a variety of sensors that can actively operate on an aqueous solution basis, the ionovoltaic devices can be utilized as a great candidate to solve these demands. However, the output energy density is low and the fabrication process is complicated to make practical use of the ionovoltaic device as the energy generating device and the active sensors. Moreover, the driving principle of the device which is not sufficiently clarified and the similar materials and structures research of the device are obstructing the various utilization development of the device. In this thesis clarifies the generation of electricity by the ionic behavior at the interface through two issues: (i) surface modification of ionovoltaic device and (ii) improvement of ionovoltaic device performance through the structural engineering. In addition, this study covers a wide range of applications as sensors and energy harvesting devices. First, applying a hydrophobic surface modification with novel electrical properties to the ionovoltaic device by engineering the hydrophobic layer, and applying it to various sensing applications using ionic behaviors at the solid-liquid interface. The ionovoltaic transducers with a negative / a positive surface potentials were developed and compared, and the effect of reversing the electrical signal by ionic behavior was confirmed for the first time. In addition, the modified ionovoltaic transducer has proven its applicability as a pH sensor and urea (bio)sensor by utilizing a pH-sensitive surface. Secondly, we identified the principle that the contact between the liquid and the solid surface is converted into the electric signal through the new type of device through the structural engineering and to apply it as the sensing and energy harvesting device. In addition, through electrode studies, we have understood the conduction mechanism and investigated the effect of resistance on ionovoltaic device performance. Through the whole structural engineering of the ionovoltaic device and the electrode modification, it was possible to control the generation time of the electric signal and to increase the energy density. Moreover, we have developed an energy harvester that can be used for the exterior and windows of buildings or automobiles through the development of high-resistance ITO mono- electrodes using the sputtering system, suggesting wide application possibilities of ionovoltaic devices.List of figures 9 Chapter 1 Introduction 16 1.1 Overview 16 1.2 Reference 19 Chapter 2 Fundamental and Literature Review 20 2.1 Working mechanism of ionovoltaic device 20 2.2 Components of ionovoltaic device 23 2.2.1. Surface of ionovoltaic devices 26 2.2.2. Structure of Ionovoltaic devices 29 2.4 References 31 Chapter 3 Surface Modification of Ionovoltaic Device and Applications 32 3.1 Introduction 32 3.2 Fabrication of pH-sensitive surface 34 3.3 Device performances and working mechanism 37 3.4 Application of ionovoltaic device as a pH sensor 48 3.4.1 pH sensing device performance and working principle 48 3.5 Application of ionovoltaic device as a urea detector 54 3.5.1 Fabrication method 55 3.5.2 Device performance and working mechanism 58 3.5.3 Possibility of ionovoltaic urea detector as a biosensor 72 3.6 Conclusion 74 3.6 Experimental details 76 3.7. Reference 79 Chapter 4 Structural Engineering of Ionovoltaic Device and Applications 85 4.1 Introduction 85 4.2 Fluidic ionovoltaic device 85 4.2.1 Fabrication method and device performance 87 4.2.2 Application of ionovoltaic device as an air-slug sensor 96 4.3 ITO mono-electrode based ionovoltaic device 100 4.3.1 Fabrication of ITO mono-electrode and ionovoltaic device 103 4.3.2 Influence of sputtering parameters on a characteristics of ITO mono-electrode based ionovoltaic device. 106 4.3.3 Application and advantages of ITO based ionovoltaic device 116 4.4 Conclusion 118 4.5 Experimental details 119 4.6 References 122 Chapter. 5 Conclusion 129 List of publications 132 요 약 (국문초록) 134Docto