Gijs Krijnen | University of Twente (original) (raw)
Papers by Gijs Krijnen
2007 IEEE Sensors, 2007
We report current developments in biomimetic flow-sensors based on mechanoreceptive sensory hairs... more We report current developments in biomimetic flow-sensors based on mechanoreceptive sensory hairs of crickets. These filiform hairs are highly perceptive to lowfrequency sound with energy sensitivities close to thermal threshold. In this work we describe hair-sensors fabricated by a combination of sacrificial poly-silicon technology, to form silicon-nitride suspended membranes, and SU8 polymer processing for fabrication of hairs with diameters of about 50 µm and up to 1 mm length. The membranes have thin chromium electrodes on top forming variable capacitors with the substrate allowing for capacitive read-out. Previously these sensors have been shown to exhibit acoustic sensitivity. Based on a hydrodynamic -mechanical interaction model we derive a figure of merit. We present optical measurements on acoustically excited hair-sensors. Experimental data and the derived models are shown to exhibit good correspondence.
2007 IEEE Sensors, 2007
We report current developments in biomimetic flow-sensors based on mechanoreceptive sensory hairs... more We report current developments in biomimetic flow-sensors based on mechanoreceptive sensory hairs of crickets. These filiform hairs are highly perceptive to lowfrequency sound with energy sensitivities close to thermal threshold. In this work we describe hair-sensors fabricated by a combination of sacrificial poly-silicon technology, to form silicon-nitride suspended membranes, and SU8 polymer processing for fabrication of hairs with diameters of about 50 µm and up to 1 mm length. The membranes have thin chromium electrodes on top forming variable capacitors with the substrate allowing for capacitive read-out. Previously these sensors have been shown to exhibit acoustic sensitivity. Based on a hydrodynamic -mechanical interaction model we derive a figure of merit. We present optical measurements on acoustically excited hair-sensors. Experimental data and the derived models are shown to exhibit good correspondence.
Bioengineered and Bioinspired Systems III, 2007
We report current developments in biomimetic flow-sensors based on flow sensitive mechano-sensors... more We report current developments in biomimetic flow-sensors based on flow sensitive mechano-sensors of crickets. Crickets have one form of acoustic sensing evolved in the form of mechanoreceptive sensory hairs. These filiform hairs are highly perceptive to low-frequency sound with energy sensitivities close to thermal threshold. In this work we describe hair-sensors fabricated by a combination of sacrificial poly-silicon technology, to form silicon-nitride suspended membranes, and SU8 polymer processing for fabrication of hairs with diameters of about 50 mum and up to 1 mm length. The membranes have thin chromium electrodes on top forming variable capacitors with the substrate that allow for capacitive read-out. Previously these sensors have been shown to exhibit acoustic sensitivity. Like for the crickets, the MEMS hair-sensors are positioned on elongated structures, resembling the cercus of crickets. In this work we present optical measurements on acoustically and electrostatically excited hair-sensors. We present adaptive control of flow-sensitivity and resonance frequency by electrostatic spring stiffness softening. Experimental data and simple analytical models derived from transduction theory are shown to exhibit good correspondence, both confirming theory and the applicability of the presented approach towards adaptation.
Bioengineered and Bioinspired Systems III, 2007
We report current developments in biomimetic flow-sensors based on flow sensitive mechano-sensors... more We report current developments in biomimetic flow-sensors based on flow sensitive mechano-sensors of crickets. Crickets have one form of acoustic sensing evolved in the form of mechanoreceptive sensory hairs. These filiform hairs are highly perceptive to low-frequency sound with energy sensitivities close to thermal threshold. In this work we describe hair-sensors fabricated by a combination of sacrificial poly-silicon technology, to form silicon-nitride suspended membranes, and SU8 polymer processing for fabrication of hairs with diameters of about 50 mum and up to 1 mm length. The membranes have thin chromium electrodes on top forming variable capacitors with the substrate that allow for capacitive read-out. Previously these sensors have been shown to exhibit acoustic sensitivity. Like for the crickets, the MEMS hair-sensors are positioned on elongated structures, resembling the cercus of crickets. In this work we present optical measurements on acoustically and electrostatically excited hair-sensors. We present adaptive control of flow-sensitivity and resonance frequency by electrostatic spring stiffness softening. Experimental data and simple analytical models derived from transduction theory are shown to exhibit good correspondence, both confirming theory and the applicability of the presented approach towards adaptation.
18th IEEE International Conference on Micro Electro Mechanical Systems, 2005. MEMS 2005., 2005
This paper presents the fabrication of flow-sensors based on the drag-force induced motion of art... more This paper presents the fabrication of flow-sensors based on the drag-force induced motion of artificial hairs connected to capacitive read-out. Artificial hairs were made either out of moulded silicon-nitride structures or by SU-8. The SU-8 hairs were suspended on membranes containing electrodes to form the variable capacitors. Silicon-rich-nitride hairs were made using a silicon wafer as a dissolvable mould. The
18th IEEE International Conference on Micro Electro Mechanical Systems, 2005. MEMS 2005., 2005
This paper presents the fabrication of flow-sensors based on the drag-force induced motion of art... more This paper presents the fabrication of flow-sensors based on the drag-force induced motion of artificial hairs connected to capacitive read-out. Artificial hairs were made either out of moulded silicon-nitride structures or by SU-8. The SU-8 hairs were suspended on membranes containing electrodes to form the variable capacitors. Silicon-rich-nitride hairs were made using a silicon wafer as a dissolvable mould. The
We report on, to our best knowledge the first, protruding electrostatic microgripper with force a... more We report on, to our best knowledge the first, protruding electrostatic microgripper with force amplification and parallel jaw motion for in-situ manipulation of sub-micrometer thick membranes in combined Scanning Electron Microscopy (SEM) / Focussed Ion Beam (FIB) machines. The gripper is used "upside-down" such that the highly doped silicon substrate shields the electrical fields resulting from the electrostatic actuation. Mechanical amplification is used to attain 3 pm jaw-displacement with up to 195 pN force from a comb-drive actuator array consisting of 1320 finger-pairs. Gripper movement was tested ex-and in-situ. The griper-jaws moved several microns in hotb cases. FIB images shifted slightly at 40 V actuation voltage but were undistorted showing the effectiveness of shielding
An innovative tool has been developed to investigate in-situ monitoring of surface modification, ... more An innovative tool has been developed to investigate in-situ monitoring of surface modification, which can be used in standard Atomic Force Microscopes (AFM). The device enables detection of topography modification on nanometer scale lateral-and subnanometer vertical resolution, which is important for reliability studies of MEMS and NEMS, where small moving parts may contact each other leading to wear. The novelty of the device is that surface modification (e.g. wear) is generated in a controlled way with a multifunctional cantilever and it is identified in-situ, the detection and the surface modification being decoupled but embedded in one and the same device.
ABSTRACT We present the controllable capillary folding of planar silicon nitride templates into 3... more ABSTRACT We present the controllable capillary folding of planar silicon nitride templates into 3D micro-structures by means of through-wafer liquid application. We demonstrate for the first time hydro-mechanical, repeatable, actuation of capillary folded structures via addition or retraction of water on demand.
Applied Physics Letters, 2004
We present a tool that can be used in standard atomic force microscope and that enables chemical,... more We present a tool that can be used in standard atomic force microscope and that enables chemical, chemical/mechanical, or physical surface modification using continuous liquid supply. The device consists of a reservoir micromachined into the probe support that is connected to fluidic channels embedded in a V-shaped cantilever. Via the fluidic channels, the liquid reaches the tip. The fluid transport
Journal of Micromechanics and Microengineering, 1999
Design, simulation, fabrication and measurement results of a new method to fabricate in-plane ori... more Design, simulation, fabrication and measurement results of a new method to fabricate in-plane oriented micro valves with use of an-isotropic wet chemical etching techniques are reported. The method is very engaging due to the simplicity, low demands on cleanroom resources, high accurate controllability and wafer-thickness independence. Integration in micro systems is facilitated by the unique possibility to obtain in-plane working devices. Performed analytical and numerical simulations as well as measurements of a duckbill valve demonstrate the functionality.
Proceedings of IEEE Sensors, 2002
International Journal of Educational Development, 2009
A fabrication scheme to realize a flow sensor array for operation in liquid which biomimics fish ... more A fabrication scheme to realize a flow sensor array for operation in liquid which biomimics fish lateral line is presented. To keep advantages of differential capacitive readout [1] we have designed a process for fabrication of thin, fully supported, flexible membranes with electrodes beneath them, on top of a substrate to prevent electrode/liquid contact and strong damping effects associated with
ABSTRACT This contribution reports on the major developments and achievements in our group on fab... more ABSTRACT This contribution reports on the major developments and achievements in our group on fabricating highly sensitive biomimetic flow-sensor arrays. The mechanoreceptive sensory hairs of crickets are taken as a model system for their ability to perceive flow signals at thermal noise levels and, moreover, to extract spatio-temporal flow information of the surroundings. To reach our final goal, i.e., a flow camera consisting of biomimetic flow-sensor arrays, most of our efforts have been focusing on increasing the performance of the biomimetic flow sensors and reliability of the fabrication process, respectively, by sensor-model optimizations and by optimization of processing procedures and materials.
The desert locust (schistocerca gregaria) has ears integrating sound reception, impedance transfo... more The desert locust (schistocerca gregaria) has ears integrating sound reception, impedance transformation and frequency discrimination in a single passive membrane. The anatomy and frequency dependent response of these ears to acoustic input have been extensively studied before. This is the inspiration for the development of a new acoustic sensor with integrated mechanical filtering. We have worked on a new micro-fabrication process based on conformal deposition of Parylene on silicon which was used to make membranes with similar variations in tension, thickness and mass density as the tympanal membrane of the locust. Mapped vibration measurements show similarities in the behaviour of the artificial membrane with the biological original, showing the potential of the approach for future energy efficient passive mechanical filtering approaches.
A 2D sound particle velocity sensor, consisting of a cross of two connected, heated wires is pres... more A 2D sound particle velocity sensor, consisting of a cross of two connected, heated wires is presented. We developed a fabrication process by which the wires become freely suspended 350 µm above the chip surface. This largely eliminates the influence of boundary layer effects and increases the temperature gradient along the wires, both due to the large distance to the silicon substrate. As a result, the sensor has increased sensitivity and reduced power consumption compared to an earlier design [1]. Furthermore, due to the fully symmetrical structure of the sensor the sensitive directions are exactly orthogonal to each other and have near identical sensitivity, thus requiring no individual calibration.
In this work the 3D extrusion printing fabrication process for intricate structures is examined. ... more In this work the 3D extrusion printing fabrication process for intricate structures is examined. Required support material normally is removed by brute force water jetting. We investigated the chemical dissolution of Fullcure 705 support material while minimally affecting Fullcure 720 structural material. From several solvents ethanol turned out to be the best with respect to selectivity and dissolution speed. We found that the dissolution process can be theoretically accurately described by the Noyes-Whitney equation, implying that the development of various structures can be predicted quite well. The fabrication process was used to make various 5 mm diameter membranes, ranging in thickness from 112 to 768 µm and their mechanical performance was characterised.
We present a biomimetic angular acceleration sensor inspired by the vestibular system, as found e... more We present a biomimetic angular acceleration sensor inspired by the vestibular system, as found e.g. in mammals and fish. The sensor consist of a fluid filled circular channel. When exposed to angular accelerations the fluid flows relative to the channel. Read-out is based on electromagnetic flow sensing (pseudo Hall effect). The sensor is made out of two 3D printed parts which, when put together, form a channel and which allow for easy mounting of permanent magnets and electrodes to measure the flow induced potential difference. Experiments indeed show an acceleration dependent output voltage. However, we find strong contributions from other than electromagnetic sources which, due to their nature and magnitude, are interesting for further research.
Three dimensional (3D) printing has recently gained attention in a variety of industries ranging ... more Three dimensional (3D) printing has recently gained attention in a variety of industries ranging from aerospace to biomedical. However, in order to create truly functional 3D printed structures, electronic functionality must be integrated into building sequence. This work explores the integration of both printed sensors (copper capacitive touch sensors) and embedded COTS sensors (surface mount accelerometers) in order to fabricate a space-flight qualification test coupon in the shape of a 1U CubeSat (10 x 10 x 10 cm) as required for stress testing. The 3D printed electronics were fabricated by an enhanced Multi 3D 3D Printing system, allowing the direct integration of 3D printed dielectric structures with electronics components fabricated together using a single non-assembly build sequence. Both sensors and structures successfully demonstrated electronic functionality after full encapsulation, and show promise for integration in space based cube satellites.
2007 IEEE Sensors, 2007
We report current developments in biomimetic flow-sensors based on mechanoreceptive sensory hairs... more We report current developments in biomimetic flow-sensors based on mechanoreceptive sensory hairs of crickets. These filiform hairs are highly perceptive to lowfrequency sound with energy sensitivities close to thermal threshold. In this work we describe hair-sensors fabricated by a combination of sacrificial poly-silicon technology, to form silicon-nitride suspended membranes, and SU8 polymer processing for fabrication of hairs with diameters of about 50 µm and up to 1 mm length. The membranes have thin chromium electrodes on top forming variable capacitors with the substrate allowing for capacitive read-out. Previously these sensors have been shown to exhibit acoustic sensitivity. Based on a hydrodynamic -mechanical interaction model we derive a figure of merit. We present optical measurements on acoustically excited hair-sensors. Experimental data and the derived models are shown to exhibit good correspondence.
2007 IEEE Sensors, 2007
We report current developments in biomimetic flow-sensors based on mechanoreceptive sensory hairs... more We report current developments in biomimetic flow-sensors based on mechanoreceptive sensory hairs of crickets. These filiform hairs are highly perceptive to lowfrequency sound with energy sensitivities close to thermal threshold. In this work we describe hair-sensors fabricated by a combination of sacrificial poly-silicon technology, to form silicon-nitride suspended membranes, and SU8 polymer processing for fabrication of hairs with diameters of about 50 µm and up to 1 mm length. The membranes have thin chromium electrodes on top forming variable capacitors with the substrate allowing for capacitive read-out. Previously these sensors have been shown to exhibit acoustic sensitivity. Based on a hydrodynamic -mechanical interaction model we derive a figure of merit. We present optical measurements on acoustically excited hair-sensors. Experimental data and the derived models are shown to exhibit good correspondence.
Bioengineered and Bioinspired Systems III, 2007
We report current developments in biomimetic flow-sensors based on flow sensitive mechano-sensors... more We report current developments in biomimetic flow-sensors based on flow sensitive mechano-sensors of crickets. Crickets have one form of acoustic sensing evolved in the form of mechanoreceptive sensory hairs. These filiform hairs are highly perceptive to low-frequency sound with energy sensitivities close to thermal threshold. In this work we describe hair-sensors fabricated by a combination of sacrificial poly-silicon technology, to form silicon-nitride suspended membranes, and SU8 polymer processing for fabrication of hairs with diameters of about 50 mum and up to 1 mm length. The membranes have thin chromium electrodes on top forming variable capacitors with the substrate that allow for capacitive read-out. Previously these sensors have been shown to exhibit acoustic sensitivity. Like for the crickets, the MEMS hair-sensors are positioned on elongated structures, resembling the cercus of crickets. In this work we present optical measurements on acoustically and electrostatically excited hair-sensors. We present adaptive control of flow-sensitivity and resonance frequency by electrostatic spring stiffness softening. Experimental data and simple analytical models derived from transduction theory are shown to exhibit good correspondence, both confirming theory and the applicability of the presented approach towards adaptation.
Bioengineered and Bioinspired Systems III, 2007
We report current developments in biomimetic flow-sensors based on flow sensitive mechano-sensors... more We report current developments in biomimetic flow-sensors based on flow sensitive mechano-sensors of crickets. Crickets have one form of acoustic sensing evolved in the form of mechanoreceptive sensory hairs. These filiform hairs are highly perceptive to low-frequency sound with energy sensitivities close to thermal threshold. In this work we describe hair-sensors fabricated by a combination of sacrificial poly-silicon technology, to form silicon-nitride suspended membranes, and SU8 polymer processing for fabrication of hairs with diameters of about 50 mum and up to 1 mm length. The membranes have thin chromium electrodes on top forming variable capacitors with the substrate that allow for capacitive read-out. Previously these sensors have been shown to exhibit acoustic sensitivity. Like for the crickets, the MEMS hair-sensors are positioned on elongated structures, resembling the cercus of crickets. In this work we present optical measurements on acoustically and electrostatically excited hair-sensors. We present adaptive control of flow-sensitivity and resonance frequency by electrostatic spring stiffness softening. Experimental data and simple analytical models derived from transduction theory are shown to exhibit good correspondence, both confirming theory and the applicability of the presented approach towards adaptation.
18th IEEE International Conference on Micro Electro Mechanical Systems, 2005. MEMS 2005., 2005
This paper presents the fabrication of flow-sensors based on the drag-force induced motion of art... more This paper presents the fabrication of flow-sensors based on the drag-force induced motion of artificial hairs connected to capacitive read-out. Artificial hairs were made either out of moulded silicon-nitride structures or by SU-8. The SU-8 hairs were suspended on membranes containing electrodes to form the variable capacitors. Silicon-rich-nitride hairs were made using a silicon wafer as a dissolvable mould. The
18th IEEE International Conference on Micro Electro Mechanical Systems, 2005. MEMS 2005., 2005
This paper presents the fabrication of flow-sensors based on the drag-force induced motion of art... more This paper presents the fabrication of flow-sensors based on the drag-force induced motion of artificial hairs connected to capacitive read-out. Artificial hairs were made either out of moulded silicon-nitride structures or by SU-8. The SU-8 hairs were suspended on membranes containing electrodes to form the variable capacitors. Silicon-rich-nitride hairs were made using a silicon wafer as a dissolvable mould. The
We report on, to our best knowledge the first, protruding electrostatic microgripper with force a... more We report on, to our best knowledge the first, protruding electrostatic microgripper with force amplification and parallel jaw motion for in-situ manipulation of sub-micrometer thick membranes in combined Scanning Electron Microscopy (SEM) / Focussed Ion Beam (FIB) machines. The gripper is used "upside-down" such that the highly doped silicon substrate shields the electrical fields resulting from the electrostatic actuation. Mechanical amplification is used to attain 3 pm jaw-displacement with up to 195 pN force from a comb-drive actuator array consisting of 1320 finger-pairs. Gripper movement was tested ex-and in-situ. The griper-jaws moved several microns in hotb cases. FIB images shifted slightly at 40 V actuation voltage but were undistorted showing the effectiveness of shielding
An innovative tool has been developed to investigate in-situ monitoring of surface modification, ... more An innovative tool has been developed to investigate in-situ monitoring of surface modification, which can be used in standard Atomic Force Microscopes (AFM). The device enables detection of topography modification on nanometer scale lateral-and subnanometer vertical resolution, which is important for reliability studies of MEMS and NEMS, where small moving parts may contact each other leading to wear. The novelty of the device is that surface modification (e.g. wear) is generated in a controlled way with a multifunctional cantilever and it is identified in-situ, the detection and the surface modification being decoupled but embedded in one and the same device.
ABSTRACT We present the controllable capillary folding of planar silicon nitride templates into 3... more ABSTRACT We present the controllable capillary folding of planar silicon nitride templates into 3D micro-structures by means of through-wafer liquid application. We demonstrate for the first time hydro-mechanical, repeatable, actuation of capillary folded structures via addition or retraction of water on demand.
Applied Physics Letters, 2004
We present a tool that can be used in standard atomic force microscope and that enables chemical,... more We present a tool that can be used in standard atomic force microscope and that enables chemical, chemical/mechanical, or physical surface modification using continuous liquid supply. The device consists of a reservoir micromachined into the probe support that is connected to fluidic channels embedded in a V-shaped cantilever. Via the fluidic channels, the liquid reaches the tip. The fluid transport
Journal of Micromechanics and Microengineering, 1999
Design, simulation, fabrication and measurement results of a new method to fabricate in-plane ori... more Design, simulation, fabrication and measurement results of a new method to fabricate in-plane oriented micro valves with use of an-isotropic wet chemical etching techniques are reported. The method is very engaging due to the simplicity, low demands on cleanroom resources, high accurate controllability and wafer-thickness independence. Integration in micro systems is facilitated by the unique possibility to obtain in-plane working devices. Performed analytical and numerical simulations as well as measurements of a duckbill valve demonstrate the functionality.
Proceedings of IEEE Sensors, 2002
International Journal of Educational Development, 2009
A fabrication scheme to realize a flow sensor array for operation in liquid which biomimics fish ... more A fabrication scheme to realize a flow sensor array for operation in liquid which biomimics fish lateral line is presented. To keep advantages of differential capacitive readout [1] we have designed a process for fabrication of thin, fully supported, flexible membranes with electrodes beneath them, on top of a substrate to prevent electrode/liquid contact and strong damping effects associated with
ABSTRACT This contribution reports on the major developments and achievements in our group on fab... more ABSTRACT This contribution reports on the major developments and achievements in our group on fabricating highly sensitive biomimetic flow-sensor arrays. The mechanoreceptive sensory hairs of crickets are taken as a model system for their ability to perceive flow signals at thermal noise levels and, moreover, to extract spatio-temporal flow information of the surroundings. To reach our final goal, i.e., a flow camera consisting of biomimetic flow-sensor arrays, most of our efforts have been focusing on increasing the performance of the biomimetic flow sensors and reliability of the fabrication process, respectively, by sensor-model optimizations and by optimization of processing procedures and materials.
The desert locust (schistocerca gregaria) has ears integrating sound reception, impedance transfo... more The desert locust (schistocerca gregaria) has ears integrating sound reception, impedance transformation and frequency discrimination in a single passive membrane. The anatomy and frequency dependent response of these ears to acoustic input have been extensively studied before. This is the inspiration for the development of a new acoustic sensor with integrated mechanical filtering. We have worked on a new micro-fabrication process based on conformal deposition of Parylene on silicon which was used to make membranes with similar variations in tension, thickness and mass density as the tympanal membrane of the locust. Mapped vibration measurements show similarities in the behaviour of the artificial membrane with the biological original, showing the potential of the approach for future energy efficient passive mechanical filtering approaches.
A 2D sound particle velocity sensor, consisting of a cross of two connected, heated wires is pres... more A 2D sound particle velocity sensor, consisting of a cross of two connected, heated wires is presented. We developed a fabrication process by which the wires become freely suspended 350 µm above the chip surface. This largely eliminates the influence of boundary layer effects and increases the temperature gradient along the wires, both due to the large distance to the silicon substrate. As a result, the sensor has increased sensitivity and reduced power consumption compared to an earlier design [1]. Furthermore, due to the fully symmetrical structure of the sensor the sensitive directions are exactly orthogonal to each other and have near identical sensitivity, thus requiring no individual calibration.
In this work the 3D extrusion printing fabrication process for intricate structures is examined. ... more In this work the 3D extrusion printing fabrication process for intricate structures is examined. Required support material normally is removed by brute force water jetting. We investigated the chemical dissolution of Fullcure 705 support material while minimally affecting Fullcure 720 structural material. From several solvents ethanol turned out to be the best with respect to selectivity and dissolution speed. We found that the dissolution process can be theoretically accurately described by the Noyes-Whitney equation, implying that the development of various structures can be predicted quite well. The fabrication process was used to make various 5 mm diameter membranes, ranging in thickness from 112 to 768 µm and their mechanical performance was characterised.
We present a biomimetic angular acceleration sensor inspired by the vestibular system, as found e... more We present a biomimetic angular acceleration sensor inspired by the vestibular system, as found e.g. in mammals and fish. The sensor consist of a fluid filled circular channel. When exposed to angular accelerations the fluid flows relative to the channel. Read-out is based on electromagnetic flow sensing (pseudo Hall effect). The sensor is made out of two 3D printed parts which, when put together, form a channel and which allow for easy mounting of permanent magnets and electrodes to measure the flow induced potential difference. Experiments indeed show an acceleration dependent output voltage. However, we find strong contributions from other than electromagnetic sources which, due to their nature and magnitude, are interesting for further research.
Three dimensional (3D) printing has recently gained attention in a variety of industries ranging ... more Three dimensional (3D) printing has recently gained attention in a variety of industries ranging from aerospace to biomedical. However, in order to create truly functional 3D printed structures, electronic functionality must be integrated into building sequence. This work explores the integration of both printed sensors (copper capacitive touch sensors) and embedded COTS sensors (surface mount accelerometers) in order to fabricate a space-flight qualification test coupon in the shape of a 1U CubeSat (10 x 10 x 10 cm) as required for stress testing. The 3D printed electronics were fabricated by an enhanced Multi 3D 3D Printing system, allowing the direct integration of 3D printed dielectric structures with electronics components fabricated together using a single non-assembly build sequence. Both sensors and structures successfully demonstrated electronic functionality after full encapsulation, and show promise for integration in space based cube satellites.