Distributed environmental monitoring

With increasingly ubiquitous use of web-based technologies in society today, autonomous sensor networks represent the future in large-scale information acquisition for applications ranging from environmental monitoring to in vivo sensing. This chapter presents a range of on-going projects with an emphasis on environmental sensing; relevant literature pertaining to sensor networks is reviewed, validated sensing applications are described and the contribution of high-resolution temporal data to better decision-making is discussed

The era of nano-bionic: 2D materials for wearable and implantable body sensors

Nano-bionics have the potential of revolutionizing modern medicine. Among nano-bionic devices, body sensors allow to monitor in real-time the health of patients, to achieve personalized medicine, and even to restore or enhance human functions. The advent of two-dimensional (2D) materials is facilitating the manufacturing of miniaturized and ultrathin bioelectronics, that can be easily integrated in the human body. Their unique electronic properties allow to efficiently transduce physical and chemical stimuli into electric current. Their flexibility and nanometric thickness facilitate the adaption and adhesion to human body. The low opacity permits to obtain transparent devices. The good cellular adhesion and reduced cytotoxicity are advantageous for the integration of the devices in vivo. Herein we review the latest and more significant examples of 2D material-based sensors for health monitoring, describing their architectures, sensing mechanisms, advantages and, as well, the challenges and drawbacks that hampers their translation into commercial clinical devices

The era of nano-bionic: 2D materials for wearable and implantable body sensors

Nano-bionics have the potential of revolutionizing modern medicine. Among nano-bionic devices, body sensors allow to monitor in real-time the health of patients, to achieve personalized medicine, and even to restore or enhance human functions. The advent of two-dimensional (2D) materials is facilitating the manufacturing of miniaturized and ultrathin bioelectronics, that can be easily integrated in the human body. Their unique electronic properties allow to efficiently transduce physical and chemical stimuli into electric current. Their flexibility and nanometric thickness facilitate the adaption and adhesion to human body. The low opacity permits to obtain transparent devices. The good cellular adhesion and reduced cytotoxicity are advantageous for the integration of the devices in vivo. Herein we review the latest and more significant examples of 2D material-based sensors for health monitoring, describing their architectures, sensing mechanisms, advantages and, as well, the challenges and drawbacks that hampers their translation into commercial clinical devices

Modular Instrumentation for Controlling and Monitoring In-Vitro Cultivation Environment and Image-based Functionality Measurements of Human Stem Cells

Artificial animal cell culture was successfully developed by Ross Harrison in 1907. But it was not until the 1940’s and 1950’s that several developments occurred, which expedited the cell culturing in-vitro (C-Vitro) to be a consistent and reproducible technique to study isolated living-cells in a controlled environment. Currently, CVitro is one of the major tools in cellular and molecular biology both in the academia and industry. They are extensively utilised to study the cellular physiology/biochemistry, to screen drugs/therapeutic compounds, to understand the effects of drugs/toxic compounds and also to identify the pathways of carcinogenesis/mutagenesis. It is also used in large scale manufacturing of vaccines and therapeutic proteins. In any experimental setup, it is important that the C-Vitro model should represent the physiological phenomena of interest with reasonable accuracy so that all experimental results are statistically consistent and reproducible. In this direction, sensors and measurement systems play important roles in in-situ detection and/or control/manipulation of cells/tissues/environment. This thesis aimed to develop new technology for tailored cell culturing and integrated measurements. Firstly, design and assembly of a portable Invert-upright microscope interchangeable modular cell culturing platform (iuCMP) was envisioned. In contrast to conventional methods, micro-scaled systems mimic the cells' natural microenvironment more precisely, facilitating accurate and tractable models. The iuCMP integrates modular measurement schemes with a mini culture chamber using biocompatible cell-friendly materials, automated environment-control (temperature and gas concentrations), oxygen sensing and simultaneous functional measurements (electrophysiological and image-based). Time lapse microscopy is very useful in cell biology, but integration of advanced >i>in-vitro/device based biological systems (e.g. lab/organ/body-on-chips, or mini-bioreactors/microfluidic systems) into conventional microscopes can be challenging in several circumstances due to multiple reasons. But in iuCMP the main advantage is, the microscope can be switched either as an inverted or as an upright system and therefore can accommodate virtually any in-vitro device. It can capture images from regions that are otherwise inaccessible by conventional microscopes, for example, cells cultured on physical or biochemical sensor systems. The modular design also allows accommodating more sensor or measurement systems quite freely. We have demonstrated the system for video-based beating analysis of cardiomyocytes, cell orientation analysis on nanocellulose, and simultaneous long-term in-situ microscopy with oxygen and temperature sensing in hypoxia. In an example application, the system was utilised for long-term temperature stressing and simultaneous mechanobiological analysis of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). For this the iuCMP together with a temperature sensor plate (TSP) and a novel non-invasive beating analysis software (CMaN—cardiomyocyte function analysis tool, scripted as a subpart of this thesis), was applied for automated temperature response studies in hiPSC-CM cultures. In-situ temperature sensing is usually challenging with bulky external sensors, but TSPs solved this issue. In the temperature response study, we showed that the relationship between hiPSC-CM beating frequency and temperature is non-linear and measured the Q10 temperature coefficients. Moreover, we observed the hiPSC-CM contractile networking, including propagation of the action potential signal between dissociated clusters and their non-invasive measurements. It was the first case where these events were reported in hiPSC-CM clusters and their noninvasive measurements by image processing. The software CMaN comes with a user-friendly interface and, is equipped with features for batch processing, movement centre detection and cluster finding. It can extract six different signals of the contractile motion of cardiomyocytes (clusters or single cells) per processing. This ensures a minimum of one useful beating signal even in the cases of complex beating videos. On the processing end, compared to similar tools, CMaN is faster, more sensitive, and computationally less expensive and allows ROI based processing. In the case of healthy cells, the waveform of the signal from the CMaN resembles an ECG signal with positive and negative segments, allowing the computation of contraction and relaxation features separately. In addition to iuCMP, a Modular optical pH measurement system (MO-pH) for 24/7 non-contact cell culture measurements was also developed. The MO-pH incorporates modular sterilisable optical parts and is used in phenol-red medium cell cultures. The modular assembly of MO-pH cassettes is unique and reusable. Measurements are carried out in a closed flow system without wasting any culture medium and requires no special manual attention or recalibrations during culture. Furthermore, a new absorption correction model was put forward that minimised errors caused e.g. by biolayers in spectrometric pH measurement, which improved the pH measurement accuracy. MO-pH has been applied in long-term human adipose stem cells (hASC) expansion cultures in CO2 dependent and independent media. Additionally, the MO-pH was also utilised to comprehend the behaviour of pH, temperature and humidity in water jacked incubators as well as to record the pH response as a function of temperature in the presence and absence of CO2 in the context of stem cell cultures. The resulting plots clearly showed the interplay between measured parameters indicating a few stress sources present all through the culture. Additionally, it provided an overall picture of behaviour of critical control parameters in an incubator and pointed out the need for bioprocess systems with automatic process monitoring and smart control for maximum yield, optimal growth and maintenance of the cells. Besides, we also integrated MO-pH into flasks with reclosable lids (RL-F) and tested its applicability in stem cell cultures. A standalone system around an RL-F flask was built by combining the cell culture, medium perfusion and optical measurements. The developed RL-F system has been successfully tested in ASC-differentiation cultures. Finally, a few trial experiments for image-based pH estimation aimed for iuCMP have also been carried out. This includes tests with LCD illumination, optical projection tomography, and webcam systems. In reality, the pH is not distributed uniformly in tissues, and has shown a gradient of up to 1.0 pH unit within 1 cm distance. Therefore, producing reliable pH maps also in in-vitro can be important in understanding various common pathologies and location of lesions. A reliable and adequately developed long-term pH mapping method will be an important addition into the iuCMP

Reaction Mechanisms and Dynamics in the Early Stage of High-κ Oxide Atomic Layer Deposition : Investigations by In Situ and Operando X-ray Photoemission Spectroscopy

Atomic layer deposition (ALD) is an outstanding deposition technique to deposit highly conformal and uniform thin films with atomic precision. In particular, ALD of transition metal oxide layers from metal amido complexes and water finds its way in several technological fields, including green energy devices and in the semiconductor industry. These ALD reactions are believed to follow a reaction scheme based on the ligand exchange mechanism, in which the surface on which deposition takes place plays a largely static role and the ligands of the used precursor are chemically unchanged during the reaction. To address the correctness of the model, time-resolved in situ and operando ambient pressure x-ray photoelectron spectroscopy (APXPS) technique was employed during the ALD of HfO2 on InAs covered by a thermal or native oxide, TiO2(101) and oxidised as well as clean Si(111).The classic ligand exchange reaction mechanism does not adequately describe the reaction path in any of the investigated sample systems. In particular, ALD of HfO2 on SiO2 follows a bimolecular reaction mechanism based on the insertion of an hydrogen atom of one of the ligands in an amido complex dimer. As a result of its bimolecular nature, this reaction can take place only on a SiO2 surface of a sufficiently high coverage of physisorbed complexes. Similarly, on TiO2 the early stage of the reaction is based on dissociative adsorption, followed by an intra- and inter- molecular reaction path, leading to the formation of new sets of surface species never before identified in any of the previous ALD models.For easily reducible surfaces, such as InAs oxide and TiO2, evidence is found for HfOx formation already during the first ALD half-cycle, due to the transfer of O atoms from the surface to the metal complex. Clearly, this contradicts the static role of the surface in standard ALD models. Interestingly, in the case of InAs covered by a thermal or native oxide, this phenomenon, which lies behind the so-called self cleaning effect, guarantees a sharp interface between the III-V material and HfO2, which is a prerequisite for next generation MOSFETs.These results open new doors for improving devices based on ALD. Time-resolved in situ and operando APXPS allows to follow the kinetics and mechanisms involved in ALD, in real time at second time resolution with significant benefit for the further improvement of general understanding of ALD reactions

The Boston University Photonics Center annual report 2010-2011

This repository item contains an annual report that summarizes activities of the Boston University Photonics Center in the 2010-2011 academic year. The report provides quantitative and descriptive information regarding photonics programs in education, interdisciplinary research, business innovation, and technology development. The Boston University Photonics Center (BUPC) is an interdisciplinary hub for education, research, scholarship, innovation, and technology development associated with practical uses of light.This report summarizes activities of the Boston University Photonics Center (BUPC) during the period July 2010 through June 2011. These activities span the Center’s complementary missions in education, research, technology development, and commercialization. In education, 21BUPC graduate students received Ph.D. diplomas. BUPC faculty taught 20 photonics courses. One graduate student was funded through the Photonics Center Dean’s Fellowship Program. BUPC supported the Research Experiences for Teachers (RET) in Biophotonic Sensors and Systems. In addition to working in the laboratories and heading to Northeastern University for shared seminars, the eight teachers split into two groups to participate in cleanroom activities. The University hosted its annual Science and Engineering Day, where the Photonics Center sponsored the Herbert J. Berman "Future of Light" Prize. Professor Goldberg’s Boston Urban Fellows Project started its sixth year. For more on our education programs, turn to the Education section on page 62. In research, BUPC faculty published journal papers spanning the field of photonics. Eleven patents were awarded to faculty this year for new innovations in the field. A number of awards for outstanding achievement in education and research were presented to BUPC faculty members. These honors include the NSF CAREER Award for Professors Altug, the 2010 R&sD 100 Award for Professor Bifano, and the Dean’s Catalyst Award for Professor Joshi. New external grant funding for the 2010-2010 fiscal year totaled $20.9M. For more information on our research activities, turn to the Research section on page 24. In technology development, this year was the beginning of a transitional period at the Photonics Center as ARL pipeline programs were completed and new research projects were proposed as part of the newly funded National Science Foundation (NSF) Industrial University Cooperative Research Center (I/UCRC) on Biophotonic Sensors and Systems. As researchers finished programs for ARL development, many successfully presented programs at the first annual I/UCRC meeting in April 2011. In the I/UCRC model, industry members of the Center provide the market vision and orient research to solve urgent market needs – in an extension of the successful ARL pipeline model in which the Department of Defense’s urgent needs motivated our research goals. For more information on our technology development pipeline and projects, turn to the Technology Development section on page 49. In commercialization, the business incubator continues to operate at capacity. Its tenants include ten technology companies with a majority having core business interests primarily in photonics and life sciences. It houses several companies founded by current and former BU faculty and students and provides students with an opportunity to assist, observe, and learn from start-up companies. For more information about business incubator activities, turn to the Business Incubation chapter in the Facilities and Equipment section on page 74. In early 2010, the BUPC unveiled a five-year strategic plan as part of the University’s comprehensive review of centers and institutes. The BUPC strategic plan will enhance the Center’s position as an international leader in photonics research. For more information about the strategic plan, turn to the BUPC Strategic Plan section on page 11

Molecular sensors for evaluating substandard anti-retroviral medication using surface-enhanced raman spectroscopy.

Doctoral Degree. University of KwaZulu-Natal, Durban.Africa has the highest number of people living with HIV and AIDS, with South Africa housing the largest Anti-retroviral treatment (ART) program in the world. In addition, the continent is troubled by the continuing growth of substandard ART medication which is imported from external continents. The World Health Organization also states that due to the limited information on this issue, adequate remedial measures cannot be put into place. As such, this study proposed the application of surface-enhanced Raman spectroscopy (SERS) as a drug screening method for ART. Sensing platforms were synthesized using a combination of metals, crosslinker organic molecules, deposition, and self-assembly methods. The platforms were used for tailored adsorption of three ART medications in their active pharmaceutical ingredient (API) form: Tenofovir (TDF), Lamivudine (LAM) and Dolutegravir (DLG) prior to evaluation with Raman spectroscopy. Molecular interactions, signal enhancement and statistical methods such as linear regression were carried out on the analytes and data from the SERS analysis showed significant differences in the sensing capabilities of the platforms based on the calibration sensitivity, analytical sensitivity, and limit of detection. The molecular composition and chemical functionality of the sensors allowed specific adsorption and preference to the complementary functional groups of the API samples which led to enhanced Raman signals on each platform. From the results obtained, it was concluded that the synthesis of tailored platforms for molecular sensing of ART medication was successful, providing potential application of these sensors in the quality control of anti-retroviral medication. Future work will entail routine molecular screening of ARVs to monitor changes in ART quality with respect to geographical location, shelf life and formulation methods

Layer by layer printing of nanomaterials for large-area, flexible electronics

Large-area electronics, including printable and flexible electronics, is an emerging concept which aims to develop electronic components in a cheaper and faster manner, especially on those non-conventional substrates. Being flexible and deformable, this new form of electronics is regarded to hold great promises for various futuristic applications including the internet of things, virtual reality, healthcare monitoring, prosthetics and robotics. However, at present, large-area electronics is still nowhere near the commercialisation stage, which is due to several problems associated with performance, uniformity and reliability, etc. Moreover, although the device’s density is not the major concern in printed electronics, there is still a merit in further increasing the total number of devices in a limited area, in order to achieve more electronic blocks, higher performance and multiple functionalities. In this context, this Ph.D. thesis focuses on the printing of various nanomaterials for the realisation of high-performance, flexible and large-area electronics. Several aspects have been covered in this thesis, including the printing dynamics of quasi-1D NWs, the contact problem in device realisation and the strategy to achieve sequential integration (3D integration) of the as-printed devices, both on rigid and flexible substrates. Promisingly, some of the devices based on the printed nanomaterial show a comparable performance to the state-of-the-art technology. With the demonstrated 3D integration strategy, a highly dense array of electronic devices can be potentially achieved by printing method. This thesis also touches on the problem associated with the circuit and system realisation. Specifically, graphene-based logic gates and NW based UV sensing circuit has been discussed, which shows the promising applications of nanomaterial-based electronics. Future work will be focusing on extending the UV sensing circuit to an active matrix sensor array