Integrated microcantilever fluid sensor as a blood coagulometer

The work presented concerns the improvement in mechanical to thermal signal of a microcantilever fluid probe for monitoring patient prothrombin time (PT) and international normalized ratio (INR) based on the physical measurement of the clotting cascade. The current device overcomes hydrodynamic damping limitations by providing an internal thermal actuation force and is realised as a disposable sensor using an integrated piezoresistive deflection measurement. Unfortunately, the piezoresistor is sensitive to thermal changes and in the current design the signal is saturated by the thermal actuation. Overcoming this problem is critical for demonstrating a blood coagulometer and in the wider field as a microsensor capable of simultaneously monitoring rheological and thermal measurements of micro-litre samples. Thermal, electrical, and mechanical testing of a new design indicates a significant reduction in the thermal crosstalk and has led to a breakthrough in distinguishing the mechanical signal when operated in moderately viscous fluids (2-3 cP). A clinical evaluation has been conducted at The Royal London Hospital to measure the accuracy and precision of the improved microcantilever fluid probe. The correlation against the standard laboratory analyser INR, from a wide range of patient clotting times(INR 0.9-6.08) is equal to 0.987 (n=87) and precision of the device measured as the percentage coefficient of variation, excluding patient samples tested < 3 times, is equal to 4.00% (n=64). The accuracy and precision is comparable to that of currently available point-of-care PT/INR devices. The response of the fluid probe in glycerol solutions indicates the potential for simultaneous measurement of rheological and thermal properties though further work is required to establish the accuracy and range of the device as a MEMS based viscometer

SST: Integrated Fluorocarbon Microsensor System Using Catalytic Modification

Selective, sensitive, and reliable sensors are urgently needed to detect air-borne halogenated volatile organic compounds (VOCs). This broad class of compounds includes chlorine, fluorine, bromine, and iodine containing hydrocarbons used as solvents, refrigerants, herbicides, and more recently as chemical warfare agents (CWAs). It is important to be able to detect very low concentrations of halocarbon solvents and insecticides because of their acute health effects even in very low concentrations. For instance, the nerve agent sarin (isopropyl methylphosphonofluoridate), first developed as an insecticide by German chemists in 1938, is so toxic that a ten minute exposure at an airborne concentration of only 65 parts per billion (ppb) can be fatal. Sarin became a household term when religious cult members on Tokyo subway trains poisoned over 5,500 people, killing 12. Sarin and other CWAs remain a significant threat to the health and safety of the general public. The goal of this project is to design a sensor system to detect and identify the composition and concentration of fluorinated VOCs. The system should be small, robust, compatible with metal oxide semiconductor (MOS) technology, cheap, if produced in large scale, and has the potential to be versatile in terms of low power consumption, detection of other gases, and integration in a portable system. The proposed VOC sensor system has three major elements that will be integrated into a microreactor flow cell: a temperature-programmable microhotplate array/reactor system which serves as the basic sensor platform; an innovative acoustic wave sensor, which detects material removal (instead of deposition) to verify and quantify the presence of fluorine; and an intelligent method, support vector machines, that will analyze the complex and high dimensional data furnished by the sensor system. The superior and complementary aspects of the three elements will be carefully integrated to create a system which is more sensitive and selective than other CWA detection systems that are commercially available or described in the research literature. While our sensor system will be developed to detect fluorinated VOCs, it can be adapted for other applications in which a target analyte can be catalytically converted for selective detection. Therefore, this investigation will examine the relationships between individual sensor element performance and joint sensor platform performance, integrated with state-of-the-art data analysis techniques. During development of the sensor system, the investigators will consider traditional reactor design concepts such as mass transfer and residence time effects, and will apply them to the emerging field of microsystems. The proposed research will provide the fundamental basis and understanding for examining multifunctional sensor platforms designed to provide extreme selectivity to targeted molecules. The project will involve interdisciplinary researchers and students and will connect to K-12 and RET programs for underrepresented students from rural areas

Recent advances in chemical sensors for soil analysis: a review

The continuously rising interest in chemical sensors' applications in environmental monitoring, for soil analysis in particular, is owed to the sufficient sensitivity and selectivity of these analytical devices, their low costs, their simple measurement setups, and the possibility to perform online and in-field analyses with them. In this review the recent advances in chemical sensors for soil analysis are summarized. The working principles of chemical sensors involved in soil analysis; their benefits and drawbacks; and select applications of both the single selective sensors and multisensor systems for assessments of main plant nutrition components, pollutants, and other important soil parameters (pH, moisture content, salinity, exhaled gases, etc.) of the past two decades with a focus on the last 5 years (from 2017 to 2021) are overviewed

Detection of Angiogenic Growth Factor by Microcantilever Biosensors

2009/2010To reach new and relevant insights in biomolecular sciences, new tools for fine and precise measurement are needed. Nowadays advances in the field of micro-electro-mechanical systems (MEMS) offer unique opportunities in the design of ultrasensitive analytical devices to support the molecular sensing investigations. Among them Microcantilever (MC) biosensors are label-free platforms that combine a biologically sensitive with a physical transducer in order to selectively and quantitatively detect the presence of specific compounds in a given external environment. Since they can be operated either as nanomechanical resonator or as surface stress sensor, MCs - activated with DNA probes or antibodies for molecular recognition - enable the measurement of mass with extraordinary sensitivity. In particular, the development of mass detector biosensor based on MC systems would permit to shift from qualitative data to quantitative measurements of key molecules involved in physiological processes. This can lead crucial informations to characterize complex mechanisms such as angiogenesis and tumor progression and to the quantification of small amounts of cancer markers, such as Angiopoietin-1 (ANG-1), and their modulation during the early stages of tumor development.XXIII Ciclo197

Microelectromechanical Systems and Devices

The advances of microelectromechanical systems (MEMS) and devices have been instrumental in the demonstration of new devices and applications, and even in the creation of new fields of research and development: bioMEMS, actuators, microfluidic devices, RF and optical MEMS. Experience indicates a need for MEMS book covering these materials as well as the most important process steps in bulk micro-machining and modeling. We are very pleased to present this book that contains 18 chapters, written by the experts in the field of MEMS. These chapters are groups into four broad sections of BioMEMS Devices, MEMS characterization and micromachining, RF and Optical MEMS, and MEMS based Actuators. The book starts with the emerging field of bioMEMS, including MEMS coil for retinal prostheses, DNA extraction by micro/bio-fluidics devices and acoustic biosensors. MEMS characterization, micromachining, macromodels, RF and Optical MEMS switches are discussed in next sections. The book concludes with the emphasis on MEMS based actuators

Development of experimental setups for the characterization of the mechanoelectrical coupling of cells in vitro

The field of mechanobiology emerged from the many evidences that mechanical forces acting on cells have a central role in their development and physiology. Cells, in fact, convert such forces into biochemical activities and gene expression in a process referred as mechanotransduction. In vitro models that mimic cell environment also from the mechanical point of view represent therefore a key tool for modelling cell behaviour and would find many applications, e.g. in drug development and tissue engineering. In this work I introduce novel tools for the study of mechanotransduction. In particular, I present a system for the evaluation of the complex response of electrically active cells, such as neurons and cardiomyocytes. This system integrates atomic force microscopy, extracellular electrophysiological recording, and optical microscopy in order to investigate cell activity in response to mechanical stimuli. I also present cell scaffolds for the in vitro study of cancer. Obtained results, although preliminary, show the potential of the proposed systems and methods to develop accurate in vitro models for mechanobiology studies

Detecting and Screening of the Prostate Cancer by Using an Optical Nanoporous Thin-Film Sensor

Prostate cancer (PC) affects elderly men more than young men. The currently used cancer biomarker, prostate-specific antigen (PSA), highly overestimates PC population. Men with high PSA levels often have to go through unnecessary, but physically painful, and expensive prosesses, such as prostate biopsies. Finding a prostate cancer marker that is produced selectively by cancer, but not by normal prostate cells will increase the reliability of PC test. In 2006, our collaborator (Dr. Girish Shah) discovered a novel protein, referred as neuroendocrine marker (NEM), secreted only by malignant prostate cells and released in blood circulation. To examine whether the combined NEM-PSA test can improve the reliability for early PC detection, we have developed a nanoporous thin film sensor that can reliably detect PSA and NEM in patient samples. The thin film sensor is fabricated from nanoporous anodic aluminum oxide and uses an optical Fabry-Perot intereferometric technique. This optical sensor has been tested for several assay paradigms, including nonspecific binding, reliability, accuracy, precision, and sensitivity. The results demonstrate that the optical nanoporous thin film sensor is reliable and extremely sensitive when used with only 0.5 µl of patient serum (or even less) to measure levels of the PSA and NEM, even in a non-cancer individual. When compared with the traditional ELISA test for PSA, the nanosensor assay is several-fold more sensitive, and it elimnates the need for labeled antigen, sample processing, complex equipment, and highly experienced individuals. These benefits, along with the low cost, should make the technology suitable for Point-of-Care application to accurately screen elderly male populations for PC and to monitor the progress of patients undergoing PC treatment. Nanoporous thin-film sensor was able to detect prostate cancer markers concentrations as low as 1 pg/ml for NEM and 20 pg/ml for PSA