Abstract—Nowadays, micro- and nanochips are usually fabricated with Silicon and/or glass. A simpl... more Abstract—Nowadays, micro- and nanochips are usually fabricated with Silicon and/or glass. A simple, low-cost and reliable integration packaging method that provides flexibility to the incorporation of electronic and fluidic devices into a system has not been fully developed yet. The use of Printed Circuit Board material as substrate to create dry film resist microfluidic channels is the core technology to provide such an integration method. The feasibility and potential of the proposed packaging method is demonstrated in this work.
Nowadays, the methods used to determine cell concentration either count the cells per volume or m... more Nowadays, the methods used to determine cell concentration either count the cells per volume or measure the cells weight per volume. This paper presents the design, fabrication and measurement of a microfluidic cell trapping device envisaged for cell concentration measurements. The work presented here focuses mainly in the fabrication of the device. Measurements are made to validate the fabricated device. The device separates different size particles by using dielectrophoresis. Horizontal as well as vertical electric fields can be used to trap the particles by controlling the amplitude and frequency of AC voltage signals. The device presented here is fabricated using low-cost and low-temperature technologies.
Measuring the ethanol/water ratio in biofuel of high ethanol content, such as E85, is important w... more Measuring the ethanol/water ratio in biofuel of high ethanol content, such as E85, is important when used in a flex-fuel engine. A capacitive probe is generally used for measuring the ethanol/gasoline ratio. However, the water content in E85 biofuel cannot be disregarded or considered constant and full composition measurement of biofuel is required. Electric impedance spectroscopy with a customized coaxial probe operating in the 10 kHz to 1 MHz frequency range was investigated. An in-depth investigation of the electrical impedance domain has led to the conclusion that additional information is required to unambiguously determine the composition of the ternary biofuel mixture. Among the different options of measurement domains and techniques, optical absorption spectroscopy in the UV spectral range between 230 and 300 nm was found to be the most appropriate. The typical absorbance in the UV range is highly dominated by gasoline, while ethanol and water are almost transparent. This approach is experimentally validated using actual fuels.
Thermal impedance spectroscopy has been investigated as a non-destructive technique to determine ... more Thermal impedance spectroscopy has been investigated as a non-destructive technique to determine the composition of ternary mixtures of biofuels. The principle of the thermal conductivity detector has been extended for measuring both the thermal conductivity and the thermal capacity of biofuel in the range between 1 to 100 Hz, using an AC-operated polysilicon heater for injecting a sinusoidal heat flux, and another polysilicon strip at a well-defined spacing or thermopile sensors for measuring the in-phase and quadrature components of the resulting AC temperature difference.
MEMS packaging is an application specific process, there are no extensively applicable standards ... more MEMS packaging is an application specific process, there are no extensively applicable standards available. This is one of the reasons why the packaging can take up to 80% of the device fabrication costs. The long-term stability of MEMS devices is determined mainly by the package. The goal of this work is to study the reliability and stability issues related to resonant mode micromechanical devices operating in ambient environment. After characterizing the failure mechanisms, we try to determine the minimum requirements for proper packaging to provide stable device operation. Stiffening effect and degrading shock response were found on thin SiN and SiC cantilever beams. The environment has strong influence on these effects; humidity increased, while nitrogen and argon decreased the stiffening effect and the shock response. These results offer cheap atmospheric packaging solution in inert gasses. Electrostatic flycatcher effect was found on crystalline Si resonator beams, which points out the necessity of a dust-free package and/or electric grounding of the resonators
In this paper, we report the separation of 6 biologically relevant organic acids in a capillary e... more In this paper, we report the separation of 6 biologically relevant organic acids in a capillary electrophoresis microchip. Electrophoretic separation was done in a fully-glass microchip into which four contactless electrodes were integrated for conductivity detection. The microchip design, the electronic interface, and the injection setup are described. Concentrations down to 50 μM (each) of the mixture of organic acids could be detected.
Ammonium levels in sweat can potentially be used to measure muscle fatigue and to diagnose partic... more Ammonium levels in sweat can potentially be used to measure muscle fatigue and to diagnose particular metabolic myopathies. To research the potential use of ammonia in sweat as a biomarker, a new real-time monitoring system is developed. This system consists of a capsule that is placed on the skin and ventilated with dry air. A metal-oxide gas sensor in the capsule detects the ammonia that is evaporated from sweat. The sensor system was built, and calibration experiments were performed. The sensors show good sensitivity from 27 mV/ppm to 1.1 mV/ppm in the desired measurement range of 1 to 30 ppm, respectively. A temperature and humidity sensor is integrated to compensate for temperature and humidity effects on the NH3 sensor.
Capacitors made of interdigitated electrodes (IDEs) as a transducer platform for the sensing of v... more Capacitors made of interdigitated electrodes (IDEs) as a transducer platform for the sensing of volatile organic compounds (VOCs) have advantages due to their lower power operation and fabrication using standard micro-fabrication techniques. Integrating a micro-electromechanical system (MEMS), such as a microhotplate with IDE capacitor, further allows study of the temperature- dependent sensing response of VOCs. In this paper, the design, fabrication, and characterization of a low-power MEMS microhotplate with IDE capacitor to study the temperature-dependent sensing response to methanol using Zeolitic imidazolate framework (ZIF-8), a class of metal-organic framework (MOF), is presented. A Titanium nitride (TiN) microhotplate with aluminum IDEs suspended on a silicon nitride membrane is fabricated and characterized. The power consumption of the ZIF-8 MOF-coated device at an operating temperature of 50 ∘ C is 4.5 mW and at 200 ∘ C it is 26 mW. A calibration methodology for the effects...
Surface and interface effects play significant roles in mechanical properties of nanostructures. ... more Surface and interface effects play significant roles in mechanical properties of nanostructures. Traditional continuum mechanics does not account for surface and interface effects on the elastic behavior of nanostructures. This work presents a general Lagrangian mechanics framework to describe the surface elastic properties. This model includes the surface effects on overall elastic behavior of a nanocantilever. It is demonstrated that the overall elastic behavior of the nanostructures is scale-dependent. Silicon nanocantilever have been fabricated with dimensions from 200 to 8 µm length, 25 to 4 µm width and 1 µm, 340 nm, and 93 nm thicknesses. The resonance behavior is studied and is compared with resonance frequency measurement in order to see at which scale other surface effects become significant.
Small (Weinheim an der Bergstrasse, Germany), Jan 8, 2017
The in situ electrochemical growth of Cu benzene-1,3,5-tricarboxylate (CuBTC) metal-organic frame... more The in situ electrochemical growth of Cu benzene-1,3,5-tricarboxylate (CuBTC) metal-organic frameworks, as an affinity layer, directly on custom-fabricated Cu interdigitated electrodes (IDEs) is described, acting as a transducer. Crystalline 5-7 µm thick CuBTC layers are grown on IDEs consisting of 100 electrodes with a width and a gap of both 50 µm and a height of 6-8 µm. These capacitive sensors are exposed to methanol and water vapor at 30 °C. The affinities show to be completely reversible with higher affinity toward water compared to methanol. For exposure to 1000 ppm methanol, a fast response is observed with a capacitance change of 5.57 pF at equilibrium. The capacitance increases in time followed diffusion-controlled kinetics (k = 2.9 mmol s(-0.5) g(-1)CuBTC ). The observed capacitance change with methanol concentration follows a Langmuir adsorption isotherm, with a value for the equilibrium affinity Ke = 174.8 bar(-1) . A volume fraction fMeOH = 0.038 is occupied upon expos...
TRANSDUCERS '03. 12th International Conference on Solid-State Sensors, Actuators and Microsystems. Digest of Technical Papers (Cat. No.03TH8664), 2000
Present paper proposes a new sensor for red blood cell (RBC) membrane stiffness measurement. The ... more Present paper proposes a new sensor for red blood cell (RBC) membrane stiffness measurement. The sensor incorporates an array of microfilters with decreasing pore size in a microchannel. Diluted blood suspension is pumped through the channel where the stiff unhealthy RBCs are blocked by the filter. The prototype sensor was fabricated on a silicon wafer. Photosensitive benzocyclobutene (BCB) was used as construction material for the filter and it was also used as adhesive material for bonding. Due to the simple structure of the device, fabrication can be done with inexpensive plastic technologies, which together with the need of only little external instrumentation makes the device applicable in isolated tropical regions.
Recent theoretical and experimental research showed that the response of micro/nanocantilevers to... more Recent theoretical and experimental research showed that the response of micro/nanocantilevers to detect materials is not always simply related to extra mass. Stiffness of adsorbates and surface stress-induced changes in the stiffness, arising from adsorption, can produce frequency shifts that are several times greater in magnitude than those induced by mass loading. Consequently, the calculated adsorbed mass does not fully represent the real adsorbed mass, making the measurements qualitative. Therefore, a proper method for measuring the stiffness of adsorbed layers has to be combined with resonance frequency measurement to quantitatively analyze changes in both the mass and the stiffness. This letter presents the theory for application of electrostatic pull-in instability for measuring the stiffness of adsorbates at the surface of cantilever resonators.
ABSTRACT A device for carrying out a reaction, which device comprises a wafer provided with a gro... more ABSTRACT A device for carrying out a reaction, which device comprises a wafer provided with a group of at least two wells. The wells are thermally separate from each other by means of a groove in a layer of the device, while parts separated by the groove are locally connected by bridges. In this way a device is provided combining great mechanical strength with good thermal insulation.
The present paper introduces a magnetic-field sensor based on a resonating single-crystal silicon... more The present paper introduces a magnetic-field sensor based on a resonating single-crystal silicon structure. The excitation of the resonator is achieved by the Lorentz force generated by a sinusoidal current flowing through a rectangular coil deposited on the surface of the structure. The amplitude of the vibration, which is proportional to the magnetic field, is detected by sensing capacitors. Because
Abstract—Nowadays, micro- and nanochips are usually fabricated with Silicon and/or glass. A simpl... more Abstract—Nowadays, micro- and nanochips are usually fabricated with Silicon and/or glass. A simple, low-cost and reliable integration packaging method that provides flexibility to the incorporation of electronic and fluidic devices into a system has not been fully developed yet. The use of Printed Circuit Board material as substrate to create dry film resist microfluidic channels is the core technology to provide such an integration method. The feasibility and potential of the proposed packaging method is demonstrated in this work.
Nowadays, the methods used to determine cell concentration either count the cells per volume or m... more Nowadays, the methods used to determine cell concentration either count the cells per volume or measure the cells weight per volume. This paper presents the design, fabrication and measurement of a microfluidic cell trapping device envisaged for cell concentration measurements. The work presented here focuses mainly in the fabrication of the device. Measurements are made to validate the fabricated device. The device separates different size particles by using dielectrophoresis. Horizontal as well as vertical electric fields can be used to trap the particles by controlling the amplitude and frequency of AC voltage signals. The device presented here is fabricated using low-cost and low-temperature technologies.
Measuring the ethanol/water ratio in biofuel of high ethanol content, such as E85, is important w... more Measuring the ethanol/water ratio in biofuel of high ethanol content, such as E85, is important when used in a flex-fuel engine. A capacitive probe is generally used for measuring the ethanol/gasoline ratio. However, the water content in E85 biofuel cannot be disregarded or considered constant and full composition measurement of biofuel is required. Electric impedance spectroscopy with a customized coaxial probe operating in the 10 kHz to 1 MHz frequency range was investigated. An in-depth investigation of the electrical impedance domain has led to the conclusion that additional information is required to unambiguously determine the composition of the ternary biofuel mixture. Among the different options of measurement domains and techniques, optical absorption spectroscopy in the UV spectral range between 230 and 300 nm was found to be the most appropriate. The typical absorbance in the UV range is highly dominated by gasoline, while ethanol and water are almost transparent. This approach is experimentally validated using actual fuels.
Thermal impedance spectroscopy has been investigated as a non-destructive technique to determine ... more Thermal impedance spectroscopy has been investigated as a non-destructive technique to determine the composition of ternary mixtures of biofuels. The principle of the thermal conductivity detector has been extended for measuring both the thermal conductivity and the thermal capacity of biofuel in the range between 1 to 100 Hz, using an AC-operated polysilicon heater for injecting a sinusoidal heat flux, and another polysilicon strip at a well-defined spacing or thermopile sensors for measuring the in-phase and quadrature components of the resulting AC temperature difference.
MEMS packaging is an application specific process, there are no extensively applicable standards ... more MEMS packaging is an application specific process, there are no extensively applicable standards available. This is one of the reasons why the packaging can take up to 80% of the device fabrication costs. The long-term stability of MEMS devices is determined mainly by the package. The goal of this work is to study the reliability and stability issues related to resonant mode micromechanical devices operating in ambient environment. After characterizing the failure mechanisms, we try to determine the minimum requirements for proper packaging to provide stable device operation. Stiffening effect and degrading shock response were found on thin SiN and SiC cantilever beams. The environment has strong influence on these effects; humidity increased, while nitrogen and argon decreased the stiffening effect and the shock response. These results offer cheap atmospheric packaging solution in inert gasses. Electrostatic flycatcher effect was found on crystalline Si resonator beams, which points out the necessity of a dust-free package and/or electric grounding of the resonators
In this paper, we report the separation of 6 biologically relevant organic acids in a capillary e... more In this paper, we report the separation of 6 biologically relevant organic acids in a capillary electrophoresis microchip. Electrophoretic separation was done in a fully-glass microchip into which four contactless electrodes were integrated for conductivity detection. The microchip design, the electronic interface, and the injection setup are described. Concentrations down to 50 μM (each) of the mixture of organic acids could be detected.
Ammonium levels in sweat can potentially be used to measure muscle fatigue and to diagnose partic... more Ammonium levels in sweat can potentially be used to measure muscle fatigue and to diagnose particular metabolic myopathies. To research the potential use of ammonia in sweat as a biomarker, a new real-time monitoring system is developed. This system consists of a capsule that is placed on the skin and ventilated with dry air. A metal-oxide gas sensor in the capsule detects the ammonia that is evaporated from sweat. The sensor system was built, and calibration experiments were performed. The sensors show good sensitivity from 27 mV/ppm to 1.1 mV/ppm in the desired measurement range of 1 to 30 ppm, respectively. A temperature and humidity sensor is integrated to compensate for temperature and humidity effects on the NH3 sensor.
Capacitors made of interdigitated electrodes (IDEs) as a transducer platform for the sensing of v... more Capacitors made of interdigitated electrodes (IDEs) as a transducer platform for the sensing of volatile organic compounds (VOCs) have advantages due to their lower power operation and fabrication using standard micro-fabrication techniques. Integrating a micro-electromechanical system (MEMS), such as a microhotplate with IDE capacitor, further allows study of the temperature- dependent sensing response of VOCs. In this paper, the design, fabrication, and characterization of a low-power MEMS microhotplate with IDE capacitor to study the temperature-dependent sensing response to methanol using Zeolitic imidazolate framework (ZIF-8), a class of metal-organic framework (MOF), is presented. A Titanium nitride (TiN) microhotplate with aluminum IDEs suspended on a silicon nitride membrane is fabricated and characterized. The power consumption of the ZIF-8 MOF-coated device at an operating temperature of 50 ∘ C is 4.5 mW and at 200 ∘ C it is 26 mW. A calibration methodology for the effects...
Surface and interface effects play significant roles in mechanical properties of nanostructures. ... more Surface and interface effects play significant roles in mechanical properties of nanostructures. Traditional continuum mechanics does not account for surface and interface effects on the elastic behavior of nanostructures. This work presents a general Lagrangian mechanics framework to describe the surface elastic properties. This model includes the surface effects on overall elastic behavior of a nanocantilever. It is demonstrated that the overall elastic behavior of the nanostructures is scale-dependent. Silicon nanocantilever have been fabricated with dimensions from 200 to 8 µm length, 25 to 4 µm width and 1 µm, 340 nm, and 93 nm thicknesses. The resonance behavior is studied and is compared with resonance frequency measurement in order to see at which scale other surface effects become significant.
Small (Weinheim an der Bergstrasse, Germany), Jan 8, 2017
The in situ electrochemical growth of Cu benzene-1,3,5-tricarboxylate (CuBTC) metal-organic frame... more The in situ electrochemical growth of Cu benzene-1,3,5-tricarboxylate (CuBTC) metal-organic frameworks, as an affinity layer, directly on custom-fabricated Cu interdigitated electrodes (IDEs) is described, acting as a transducer. Crystalline 5-7 µm thick CuBTC layers are grown on IDEs consisting of 100 electrodes with a width and a gap of both 50 µm and a height of 6-8 µm. These capacitive sensors are exposed to methanol and water vapor at 30 °C. The affinities show to be completely reversible with higher affinity toward water compared to methanol. For exposure to 1000 ppm methanol, a fast response is observed with a capacitance change of 5.57 pF at equilibrium. The capacitance increases in time followed diffusion-controlled kinetics (k = 2.9 mmol s(-0.5) g(-1)CuBTC ). The observed capacitance change with methanol concentration follows a Langmuir adsorption isotherm, with a value for the equilibrium affinity Ke = 174.8 bar(-1) . A volume fraction fMeOH = 0.038 is occupied upon expos...
TRANSDUCERS '03. 12th International Conference on Solid-State Sensors, Actuators and Microsystems. Digest of Technical Papers (Cat. No.03TH8664), 2000
Present paper proposes a new sensor for red blood cell (RBC) membrane stiffness measurement. The ... more Present paper proposes a new sensor for red blood cell (RBC) membrane stiffness measurement. The sensor incorporates an array of microfilters with decreasing pore size in a microchannel. Diluted blood suspension is pumped through the channel where the stiff unhealthy RBCs are blocked by the filter. The prototype sensor was fabricated on a silicon wafer. Photosensitive benzocyclobutene (BCB) was used as construction material for the filter and it was also used as adhesive material for bonding. Due to the simple structure of the device, fabrication can be done with inexpensive plastic technologies, which together with the need of only little external instrumentation makes the device applicable in isolated tropical regions.
Recent theoretical and experimental research showed that the response of micro/nanocantilevers to... more Recent theoretical and experimental research showed that the response of micro/nanocantilevers to detect materials is not always simply related to extra mass. Stiffness of adsorbates and surface stress-induced changes in the stiffness, arising from adsorption, can produce frequency shifts that are several times greater in magnitude than those induced by mass loading. Consequently, the calculated adsorbed mass does not fully represent the real adsorbed mass, making the measurements qualitative. Therefore, a proper method for measuring the stiffness of adsorbed layers has to be combined with resonance frequency measurement to quantitatively analyze changes in both the mass and the stiffness. This letter presents the theory for application of electrostatic pull-in instability for measuring the stiffness of adsorbates at the surface of cantilever resonators.
ABSTRACT A device for carrying out a reaction, which device comprises a wafer provided with a gro... more ABSTRACT A device for carrying out a reaction, which device comprises a wafer provided with a group of at least two wells. The wells are thermally separate from each other by means of a groove in a layer of the device, while parts separated by the groove are locally connected by bridges. In this way a device is provided combining great mechanical strength with good thermal insulation.
The present paper introduces a magnetic-field sensor based on a resonating single-crystal silicon... more The present paper introduces a magnetic-field sensor based on a resonating single-crystal silicon structure. The excitation of the resonator is achieved by the Lorentz force generated by a sinusoidal current flowing through a rectangular coil deposited on the surface of the structure. The amplitude of the vibration, which is proportional to the magnetic field, is detected by sensing capacitors. Because
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Papers by Andre Bossche