Gert Van Heck - Academia.edu (original) (raw)

Papers by Gert Van Heck

Langmuir, 2009

Miniaturization of biosensors is envisaged by the development of biochips consisting of parallel ... more Miniaturization of biosensors is envisaged by the development of biochips consisting of parallel microarray patterns of binding sites on rigid substrates, such as glass or silicon. Thin plastic substrates are promising flexible alternatives because of the possibility for large-area roll-to-roll manufacturing of disposable chips at lower costs. Mature optical lithography technology faces many challenges when used to pattern flexible foils as a result of the substrate instabilities, especially at higher temperatures. In this work, flexible biochips with gold electrode patterns were fabricated on thin polyethylene naphthalate (PEN) foils using photolithography. The gold electrode structures of the chips were manufactured by direct metal patterning and by lift-off processing. Both methodologies resulted in well-defined electrode patterns as concluded from optical microscopy and scanning electron microscopy (SEM) characterization and resistance measurements. The biochips were successfully employed for the electrical and optical detection of DNA molecules. The DNA detection was based on the immobilization of capture DNA between electrode gaps, hybridization with biotin-labeled target DNA, and enzymatic silver enhancement.

Electro-Optical Remote Sensing, Detection, and Photonic Technologies and Their Applications, 2007

Monitoring of personal wellbeing and optimizing human performance are areas where sensors have on... more Monitoring of personal wellbeing and optimizing human performance are areas where sensors have only begun to be used. One of the reasons for this is the specific demands that these application areas put on the underlying technology and system properties. In many cases these sensors will be integrated in clothing, be worn on the skin, or may even be placed inside the body. This implies that flexibility and wearability of the systems is essential for their success. Devices based on polymer semiconductors allow for these demands since they can be fabricated with thin film technology. The use of thin film device technology allows for the fabrication of very thin sensors (e.g. integrated in food product packaging), flexible or bendable sensors in wearables, large area/distributed sensors, and intrinsically low-cost applications in disposable products. With thin film device technology a high level of integration can be achieved with parts that analyze signals, process and store data, and interact over a network. Integration of all these functions will inherently lead to better cost/performance ratios, especially if printing and other standard polymer technology such as high precision moulding is applied for the fabrication. In this paper we present an optical transmission sensor array based on polymer semiconductor devices made by thin film technology. The organic devices, light emitting diodes, photodiodes and selective medium chip, are integrated with classic electronic components. Together they form a versatile sensor platform that allows for the quantitative measurement of 100 channels and communicates wireless with a computer. The emphasis is given to the sensor principle, the design, fabrication technology and integration of the thin film devices.

2008 IEEE Sensors Applications Symposium, 2008

Organic electronic devices are ideal for incorporation in sensor devices due to their reduced thi... more Organic electronic devices are ideal for incorporation in sensor devices due to their reduced thickness, weight, and flexibility. Here, we show that organic light emitting diodes (OLED) and organic photodiodes (OPD) can be used in a wide range of optical sensors. Printing technologies allow for cheap production of devices. Using a modular build up of these and additional components such as organic circuitry and/or embedded thinned silicon dies will allow for an almost 2 dimensional design with a variety of resulting products. The emphasis will be given on the design and the fabrication of modules for a pulse-oximeter device and integration into a wireless smart bandage. Results will be shown of a proof of concept device.

The composition of a mixture containing at least two reactive components is determined by means o... more The composition of a mixture containing at least two reactive components is determined by means of spectroscopy. The measured reflection spectrum of the mixture is compared with at least one standard spectrum of a mixture with a predetermined mixing proportion. Also claimed is an apparatus for the above process, comprising a spectrophotometer and attached probe and calculating unit. The unit has a memory for storing at least one standard spectrum, corresponding to a selected mixture proportion, and a means to compare this spectrum with the unknown. The composition of a mixture containing at least two reactive components is preferably determined by means of reflection spectroscopy. The mixture can preferably consist of an epoxy-type resin and an amine-type hardener or an hydroxyl-type resin and an isocyanate-type hardener.

Textile Research Journal, Feb 27, 2015

Integration of electronic functionalities into textiles adds to the value of textiles. It allows ... more Integration of electronic functionalities into textiles adds to the value of textiles. It allows measuring, detecting, actuating and treating or communicating with a body or object. These added values can render the smart textiles very useful, fun, supporting, protecting or even lifesaving. It is, however, important for the comfort, acceptance and functionality to have integration of electronics as unobtrusive as possible. One elegant unobtrusive method of integration is to have circuitry included in the textile and mount components to this circuitry. Conducting yarns introduced by weaving, knitting or embroidery are attractive candidates to compose the circuitry as they do not disturb the textile nature of the system and are processable by the mentioned conventional textile technologies. In the case that these smart textiles are worn by humans under dynamic circumstances, the system is exposed to mechanical stress. In this paper we report the results of studies on the failure modes of Ag-coated nylon yarns, which are applied on textile carriers by means of stitching or soutache embroidery. The test methods varied in combinations of mechanical stress, such as shearing, bending and tension, and support to better understand the process of deterioration of the yarns when these are mechanically stressed. The delamination of the Ag coating from the yarns leads to unstable resistance values in non-static conditions. The mechanical forces, such as shearing, bending and tension, cause progressively more damage to the filaments of the yarns. This leads to a reduction of the electrical conductivity.

SID Symposium Digest of Technical Papers, 2016

Organic Electronics Physics Materials Applications 8 14 1966 1971, Aug 1, 2013

ABSTRACT In this paper, we successfully fabricated and operated passive matrix P(VDF–TrFE) transi... more ABSTRACT In this paper, we successfully fabricated and operated passive matrix P(VDF–TrFE) transistor arrays, i.e. memory arrays in which no pass-transistors or other additional electronic components are used. Because of the smaller cell, a higher integration density is possible. We demonstrate arrays up to a size of 16 × 16, processed on thin (25 μm) poly(ethylene naphthalate) substrates, using Indium–Gallium–Zinc–Oxide (IGZO) as the semiconductor and 200 nm-thick P(VDF–TrFE) as a ferroelectric gate dielectric. The memory transistors have remnant current modulations of ∼105 with a retention time of more than 12 days. They can be switched in less than 1 μs at operating voltages of 25 V. Switching speed is strongly decreased with decreasing voltage: at ∼10 V the transistors do not switch within 10 s. This difference in switching speed of more than 4 orders in magnitude when changing the electric field by a factor of only 2.5 makes these memories robust towards disturb voltages, and forms the basis of integration of these transistors in passive matrix-addressable transistor arrays that contains only one (memory) transistor per cell. It is shown that with current technology and memory characteristics it is possible to scale up the array size in the future.

Organic-based Chemical and Biological Sensors, 2007

Sensors integrated into food packages could benefit consumers by ensuring freshness and quality w... more Sensors integrated into food packages could benefit consumers by ensuring freshness and quality while allowing retail industry to more efficiently manage food stocks and product authenticity. Here we present smart radio-frequency labels with sensors able to measure temperature, humidity and the presence of volatile amine compounds. The labels are made via high quality screen printing and lamination technologies on low cost foils in combination with pick and place technology. As a case study the smart labels are used to quantify the freshness of fish.

This paper describes the dynamics of capillary self-alignment of components with initial shift of... more This paper describes the dynamics of capillary self-alignment of components with initial shift offsets from matching receptor sites. The analysis of the full uniaxial self-alignment dynamics of foil-based mesoscopic dies from pre-alignment to final settling evidenced three distinct, sequential regimes impacting the process performance. The dependence of accuracy, alignment time and repeatability of capillary self-alignment on control parameters such as size, weight, surface energy and initial offset of assembling dies was investigated. Finally, we studied the influence of the dynamic coupling between the degenerate oscillation modes of the system on the alignment performance by means of pre-defined biaxial offsets.

IEEE Transactions on Robotics, 2015

ABSTRACT

IFMBE Proceedings, 2009

ABSTRACT Organic electronic devices produced on foil open promising new perspectives for incorpor... more ABSTRACT Organic electronic devices produced on foil open promising new perspectives for incorporation in disposable medical devices or sterile packaging materials because they are thin, lightweight and flexible. However, for economical viable applications reliable and cheap large scale production methods are required. Such production technologies (e.g. roll-to-roll manufacturing) are being developed and ruggedized within the Holst Centre (an open innovation institute founded by IMEC and TNO). These technologies form the basis for several strategic programs. As examples of the possibilities with Systems In Foil (SIFs) we discuss 2 ongoing programs: Smart bandage and smart blisters. Smart bandage contains a matrix of organic LEDs (OLEDs) and Organic Photo Diodes (OPDs) allowing spatially resolved photoplethysmographic monitoring of e.g. a wound area, without the need for bandage removal. This is beneficial for monitoring the healing of wounds where unnecessary bandage removal causes much pain and/or damage to the recovering tissue. A smart blister contains an electronic circuit that registers date and time when a blister compartment is opened. It communicates with the outside world via an RFID. Such features enable Real Time Medication Event Monitoring and Failure Mode and Effects Analysis within the pharmaceutical distribution chain, which can help to improve therapy effectiveness, decrease the costs of unused drugs and help prevent drug-counterfeiting. It can be expected that cheap organic circuits printed on flexible foil will open similar new perspectives for a wide variety of other applications in medicine and pharmacology.

Organic Field-Effect Transistors VII and Organic Semiconductors in Sensors and Bioelectronics, 2008

Sensors based on organic electronic devices are emerging in a wide range of application areas. He... more Sensors based on organic electronic devices are emerging in a wide range of application areas. Here we present a sensor platform using organic light emitting diodes (OLED) and organic photodiodes (OPD) as active components. By means of lamination and interconnection technology the functional foils with OLED and OPD arrays form an in-plane optical sensor platform (IPOS). This platform can be extended with a wireless data and signal processing unit yielding a sensor node. The focus of our research is to engage the node in a healthcare application, in which a bandage is able to monitor the vital signs of a person, a so-called Smart Bandage. One of the principles that is described here is based on measuring the absorption modulation of blood volume induced by the pulse (photoplethysmography). The information from such a bandage could be used to monitor wound healing by measuring the perfusion in the skin. The OLED and OPD devices are manufactured on separate foils and glass substrates by means of printing and coating technologies. Furthermore, the modular approach allows for the application of the optical sensing unit in a variety of other fields including chemical sensing. This, ultimately enables the measurement of a large variety of physiological parameters using the same bandage and the same basic sensor architecture. Here we discuss the build-up of our device in general terms. Specific characteristics of the used OLEDs and OPDs are shown and finally we demonstrate the functionality by simultaneously recorded photoplethysmograms of our device and a clinical pulseoximeter.

Electro-Optical Remote Sensing, Detection, and Photonic Technologies and Their Applications, 2007

Monitoring of personal wellbeing and optimizing human performance are areas where sensors have on... more Monitoring of personal wellbeing and optimizing human performance are areas where sensors have only begun to be used. One of the reasons for this is the specific demands that these application areas put on the underlying technology and system properties. In many cases these sensors will be integrated in clothing, be worn on the skin, or may even be placed

Journal of Microelectromechanical Systems, 2015

This paper introduces a new integration technology for cost-effective high-precision mechanical a... more This paper introduces a new integration technology for cost-effective high-precision mechanical and electrical integration of mesoscopic functional foil components onto foil substrates. The foil-to-foil assembly process is based on topological surface structuring via laser patterning that enables accurate capillarity-driven self-alignment of foil dies. The concurrent establishment of high-yield electrical interconnections is obtained through conductive adhesives. The foil surface energy controls the acceptance window of initial offsets for optimal self-alignment performance. The proposed topological patterning and system design enable alignment accuracies for centimeter-sized foil dies as high as 15 µm, barely influenced by the evaporation of the assembly liquid and curing of the conductive paste. Full foil-tofoil system integration is demonstrated through the electrically functional assembly of an array of Au-sputtered capacitive humidity sensors onto a patterned base foil circuitry.

Applied Physics Express, 2014

ABSTRACT

Organic Electronics, 2013

ABSTRACT In this paper, we successfully fabricated and operated passive matrix P(VDF–TrFE) transi... more ABSTRACT In this paper, we successfully fabricated and operated passive matrix P(VDF–TrFE) transistor arrays, i.e. memory arrays in which no pass-transistors or other additional electronic components are used. Because of the smaller cell, a higher integration density is possible. We demonstrate arrays up to a size of 16 × 16, processed on thin (25 μm) poly(ethylene naphthalate) substrates, using Indium–Gallium–Zinc–Oxide (IGZO) as the semiconductor and 200 nm-thick P(VDF–TrFE) as a ferroelectric gate dielectric. The memory transistors have remnant current modulations of ∼105 with a retention time of more than 12 days. They can be switched in less than 1 μs at operating voltages of 25 V. Switching speed is strongly decreased with decreasing voltage: at ∼10 V the transistors do not switch within 10 s. This difference in switching speed of more than 4 orders in magnitude when changing the electric field by a factor of only 2.5 makes these memories robust towards disturb voltages, and forms the basis of integration of these transistors in passive matrix-addressable transistor arrays that contains only one (memory) transistor per cell. It is shown that with current technology and memory characteristics it is possible to scale up the array size in the future.

Langmuir, 2009

Miniaturization of biosensors is envisaged by the development of biochips consisting of parallel ... more Miniaturization of biosensors is envisaged by the development of biochips consisting of parallel microarray patterns of binding sites on rigid substrates, such as glass or silicon. Thin plastic substrates are promising flexible alternatives because of the possibility for large-area roll-to-roll manufacturing of disposable chips at lower costs. Mature optical lithography technology faces many challenges when used to pattern flexible foils as a result of the substrate instabilities, especially at higher temperatures. In this work, flexible biochips with gold electrode patterns were fabricated on thin polyethylene naphthalate (PEN) foils using photolithography. The gold electrode structures of the chips were manufactured by direct metal patterning and by lift-off processing. Both methodologies resulted in well-defined electrode patterns as concluded from optical microscopy and scanning electron microscopy (SEM) characterization and resistance measurements. The biochips were successfully employed for the electrical and optical detection of DNA molecules. The DNA detection was based on the immobilization of capture DNA between electrode gaps, hybridization with biotin-labeled target DNA, and enzymatic silver enhancement.

Langmuir, 2009

Miniaturization of biosensors is envisaged by the development of biochips consisting of parallel ... more Miniaturization of biosensors is envisaged by the development of biochips consisting of parallel microarray patterns of binding sites on rigid substrates, such as glass or silicon. Thin plastic substrates are promising flexible alternatives because of the possibility for large-area roll-to-roll manufacturing of disposable chips at lower costs. Mature optical lithography technology faces many challenges when used to pattern flexible foils as a result of the substrate instabilities, especially at higher temperatures. In this work, flexible biochips with gold electrode patterns were fabricated on thin polyethylene naphthalate (PEN) foils using photolithography. The gold electrode structures of the chips were manufactured by direct metal patterning and by lift-off processing. Both methodologies resulted in well-defined electrode patterns as concluded from optical microscopy and scanning electron microscopy (SEM) characterization and resistance measurements. The biochips were successfully employed for the electrical and optical detection of DNA molecules. The DNA detection was based on the immobilization of capture DNA between electrode gaps, hybridization with biotin-labeled target DNA, and enzymatic silver enhancement.

Electro-Optical Remote Sensing, Detection, and Photonic Technologies and Their Applications, 2007

Monitoring of personal wellbeing and optimizing human performance are areas where sensors have on... more Monitoring of personal wellbeing and optimizing human performance are areas where sensors have only begun to be used. One of the reasons for this is the specific demands that these application areas put on the underlying technology and system properties. In many cases these sensors will be integrated in clothing, be worn on the skin, or may even be placed inside the body. This implies that flexibility and wearability of the systems is essential for their success. Devices based on polymer semiconductors allow for these demands since they can be fabricated with thin film technology. The use of thin film device technology allows for the fabrication of very thin sensors (e.g. integrated in food product packaging), flexible or bendable sensors in wearables, large area/distributed sensors, and intrinsically low-cost applications in disposable products. With thin film device technology a high level of integration can be achieved with parts that analyze signals, process and store data, and interact over a network. Integration of all these functions will inherently lead to better cost/performance ratios, especially if printing and other standard polymer technology such as high precision moulding is applied for the fabrication. In this paper we present an optical transmission sensor array based on polymer semiconductor devices made by thin film technology. The organic devices, light emitting diodes, photodiodes and selective medium chip, are integrated with classic electronic components. Together they form a versatile sensor platform that allows for the quantitative measurement of 100 channels and communicates wireless with a computer. The emphasis is given to the sensor principle, the design, fabrication technology and integration of the thin film devices.

2008 IEEE Sensors Applications Symposium, 2008

Organic electronic devices are ideal for incorporation in sensor devices due to their reduced thi... more Organic electronic devices are ideal for incorporation in sensor devices due to their reduced thickness, weight, and flexibility. Here, we show that organic light emitting diodes (OLED) and organic photodiodes (OPD) can be used in a wide range of optical sensors. Printing technologies allow for cheap production of devices. Using a modular build up of these and additional components such as organic circuitry and/or embedded thinned silicon dies will allow for an almost 2 dimensional design with a variety of resulting products. The emphasis will be given on the design and the fabrication of modules for a pulse-oximeter device and integration into a wireless smart bandage. Results will be shown of a proof of concept device.

The composition of a mixture containing at least two reactive components is determined by means o... more The composition of a mixture containing at least two reactive components is determined by means of spectroscopy. The measured reflection spectrum of the mixture is compared with at least one standard spectrum of a mixture with a predetermined mixing proportion. Also claimed is an apparatus for the above process, comprising a spectrophotometer and attached probe and calculating unit. The unit has a memory for storing at least one standard spectrum, corresponding to a selected mixture proportion, and a means to compare this spectrum with the unknown. The composition of a mixture containing at least two reactive components is preferably determined by means of reflection spectroscopy. The mixture can preferably consist of an epoxy-type resin and an amine-type hardener or an hydroxyl-type resin and an isocyanate-type hardener.

Textile Research Journal, Feb 27, 2015

Integration of electronic functionalities into textiles adds to the value of textiles. It allows ... more Integration of electronic functionalities into textiles adds to the value of textiles. It allows measuring, detecting, actuating and treating or communicating with a body or object. These added values can render the smart textiles very useful, fun, supporting, protecting or even lifesaving. It is, however, important for the comfort, acceptance and functionality to have integration of electronics as unobtrusive as possible. One elegant unobtrusive method of integration is to have circuitry included in the textile and mount components to this circuitry. Conducting yarns introduced by weaving, knitting or embroidery are attractive candidates to compose the circuitry as they do not disturb the textile nature of the system and are processable by the mentioned conventional textile technologies. In the case that these smart textiles are worn by humans under dynamic circumstances, the system is exposed to mechanical stress. In this paper we report the results of studies on the failure modes of Ag-coated nylon yarns, which are applied on textile carriers by means of stitching or soutache embroidery. The test methods varied in combinations of mechanical stress, such as shearing, bending and tension, and support to better understand the process of deterioration of the yarns when these are mechanically stressed. The delamination of the Ag coating from the yarns leads to unstable resistance values in non-static conditions. The mechanical forces, such as shearing, bending and tension, cause progressively more damage to the filaments of the yarns. This leads to a reduction of the electrical conductivity.

SID Symposium Digest of Technical Papers, 2016

Organic Electronics Physics Materials Applications 8 14 1966 1971, Aug 1, 2013

ABSTRACT In this paper, we successfully fabricated and operated passive matrix P(VDF–TrFE) transi... more ABSTRACT In this paper, we successfully fabricated and operated passive matrix P(VDF–TrFE) transistor arrays, i.e. memory arrays in which no pass-transistors or other additional electronic components are used. Because of the smaller cell, a higher integration density is possible. We demonstrate arrays up to a size of 16 × 16, processed on thin (25 μm) poly(ethylene naphthalate) substrates, using Indium–Gallium–Zinc–Oxide (IGZO) as the semiconductor and 200 nm-thick P(VDF–TrFE) as a ferroelectric gate dielectric. The memory transistors have remnant current modulations of ∼105 with a retention time of more than 12 days. They can be switched in less than 1 μs at operating voltages of 25 V. Switching speed is strongly decreased with decreasing voltage: at ∼10 V the transistors do not switch within 10 s. This difference in switching speed of more than 4 orders in magnitude when changing the electric field by a factor of only 2.5 makes these memories robust towards disturb voltages, and forms the basis of integration of these transistors in passive matrix-addressable transistor arrays that contains only one (memory) transistor per cell. It is shown that with current technology and memory characteristics it is possible to scale up the array size in the future.

Organic-based Chemical and Biological Sensors, 2007

Sensors integrated into food packages could benefit consumers by ensuring freshness and quality w... more Sensors integrated into food packages could benefit consumers by ensuring freshness and quality while allowing retail industry to more efficiently manage food stocks and product authenticity. Here we present smart radio-frequency labels with sensors able to measure temperature, humidity and the presence of volatile amine compounds. The labels are made via high quality screen printing and lamination technologies on low cost foils in combination with pick and place technology. As a case study the smart labels are used to quantify the freshness of fish.

This paper describes the dynamics of capillary self-alignment of components with initial shift of... more This paper describes the dynamics of capillary self-alignment of components with initial shift offsets from matching receptor sites. The analysis of the full uniaxial self-alignment dynamics of foil-based mesoscopic dies from pre-alignment to final settling evidenced three distinct, sequential regimes impacting the process performance. The dependence of accuracy, alignment time and repeatability of capillary self-alignment on control parameters such as size, weight, surface energy and initial offset of assembling dies was investigated. Finally, we studied the influence of the dynamic coupling between the degenerate oscillation modes of the system on the alignment performance by means of pre-defined biaxial offsets.

IEEE Transactions on Robotics, 2015

ABSTRACT

IFMBE Proceedings, 2009

ABSTRACT Organic electronic devices produced on foil open promising new perspectives for incorpor... more ABSTRACT Organic electronic devices produced on foil open promising new perspectives for incorporation in disposable medical devices or sterile packaging materials because they are thin, lightweight and flexible. However, for economical viable applications reliable and cheap large scale production methods are required. Such production technologies (e.g. roll-to-roll manufacturing) are being developed and ruggedized within the Holst Centre (an open innovation institute founded by IMEC and TNO). These technologies form the basis for several strategic programs. As examples of the possibilities with Systems In Foil (SIFs) we discuss 2 ongoing programs: Smart bandage and smart blisters. Smart bandage contains a matrix of organic LEDs (OLEDs) and Organic Photo Diodes (OPDs) allowing spatially resolved photoplethysmographic monitoring of e.g. a wound area, without the need for bandage removal. This is beneficial for monitoring the healing of wounds where unnecessary bandage removal causes much pain and/or damage to the recovering tissue. A smart blister contains an electronic circuit that registers date and time when a blister compartment is opened. It communicates with the outside world via an RFID. Such features enable Real Time Medication Event Monitoring and Failure Mode and Effects Analysis within the pharmaceutical distribution chain, which can help to improve therapy effectiveness, decrease the costs of unused drugs and help prevent drug-counterfeiting. It can be expected that cheap organic circuits printed on flexible foil will open similar new perspectives for a wide variety of other applications in medicine and pharmacology.

Organic Field-Effect Transistors VII and Organic Semiconductors in Sensors and Bioelectronics, 2008

Sensors based on organic electronic devices are emerging in a wide range of application areas. He... more Sensors based on organic electronic devices are emerging in a wide range of application areas. Here we present a sensor platform using organic light emitting diodes (OLED) and organic photodiodes (OPD) as active components. By means of lamination and interconnection technology the functional foils with OLED and OPD arrays form an in-plane optical sensor platform (IPOS). This platform can be extended with a wireless data and signal processing unit yielding a sensor node. The focus of our research is to engage the node in a healthcare application, in which a bandage is able to monitor the vital signs of a person, a so-called Smart Bandage. One of the principles that is described here is based on measuring the absorption modulation of blood volume induced by the pulse (photoplethysmography). The information from such a bandage could be used to monitor wound healing by measuring the perfusion in the skin. The OLED and OPD devices are manufactured on separate foils and glass substrates by means of printing and coating technologies. Furthermore, the modular approach allows for the application of the optical sensing unit in a variety of other fields including chemical sensing. This, ultimately enables the measurement of a large variety of physiological parameters using the same bandage and the same basic sensor architecture. Here we discuss the build-up of our device in general terms. Specific characteristics of the used OLEDs and OPDs are shown and finally we demonstrate the functionality by simultaneously recorded photoplethysmograms of our device and a clinical pulseoximeter.

Electro-Optical Remote Sensing, Detection, and Photonic Technologies and Their Applications, 2007

Monitoring of personal wellbeing and optimizing human performance are areas where sensors have on... more Monitoring of personal wellbeing and optimizing human performance are areas where sensors have only begun to be used. One of the reasons for this is the specific demands that these application areas put on the underlying technology and system properties. In many cases these sensors will be integrated in clothing, be worn on the skin, or may even be placed

Journal of Microelectromechanical Systems, 2015

This paper introduces a new integration technology for cost-effective high-precision mechanical a... more This paper introduces a new integration technology for cost-effective high-precision mechanical and electrical integration of mesoscopic functional foil components onto foil substrates. The foil-to-foil assembly process is based on topological surface structuring via laser patterning that enables accurate capillarity-driven self-alignment of foil dies. The concurrent establishment of high-yield electrical interconnections is obtained through conductive adhesives. The foil surface energy controls the acceptance window of initial offsets for optimal self-alignment performance. The proposed topological patterning and system design enable alignment accuracies for centimeter-sized foil dies as high as 15 µm, barely influenced by the evaporation of the assembly liquid and curing of the conductive paste. Full foil-tofoil system integration is demonstrated through the electrically functional assembly of an array of Au-sputtered capacitive humidity sensors onto a patterned base foil circuitry.

Applied Physics Express, 2014

ABSTRACT

Organic Electronics, 2013

ABSTRACT In this paper, we successfully fabricated and operated passive matrix P(VDF–TrFE) transi... more ABSTRACT In this paper, we successfully fabricated and operated passive matrix P(VDF–TrFE) transistor arrays, i.e. memory arrays in which no pass-transistors or other additional electronic components are used. Because of the smaller cell, a higher integration density is possible. We demonstrate arrays up to a size of 16 × 16, processed on thin (25 μm) poly(ethylene naphthalate) substrates, using Indium–Gallium–Zinc–Oxide (IGZO) as the semiconductor and 200 nm-thick P(VDF–TrFE) as a ferroelectric gate dielectric. The memory transistors have remnant current modulations of ∼105 with a retention time of more than 12 days. They can be switched in less than 1 μs at operating voltages of 25 V. Switching speed is strongly decreased with decreasing voltage: at ∼10 V the transistors do not switch within 10 s. This difference in switching speed of more than 4 orders in magnitude when changing the electric field by a factor of only 2.5 makes these memories robust towards disturb voltages, and forms the basis of integration of these transistors in passive matrix-addressable transistor arrays that contains only one (memory) transistor per cell. It is shown that with current technology and memory characteristics it is possible to scale up the array size in the future.

Langmuir, 2009

Miniaturization of biosensors is envisaged by the development of biochips consisting of parallel ... more Miniaturization of biosensors is envisaged by the development of biochips consisting of parallel microarray patterns of binding sites on rigid substrates, such as glass or silicon. Thin plastic substrates are promising flexible alternatives because of the possibility for large-area roll-to-roll manufacturing of disposable chips at lower costs. Mature optical lithography technology faces many challenges when used to pattern flexible foils as a result of the substrate instabilities, especially at higher temperatures. In this work, flexible biochips with gold electrode patterns were fabricated on thin polyethylene naphthalate (PEN) foils using photolithography. The gold electrode structures of the chips were manufactured by direct metal patterning and by lift-off processing. Both methodologies resulted in well-defined electrode patterns as concluded from optical microscopy and scanning electron microscopy (SEM) characterization and resistance measurements. The biochips were successfully employed for the electrical and optical detection of DNA molecules. The DNA detection was based on the immobilization of capture DNA between electrode gaps, hybridization with biotin-labeled target DNA, and enzymatic silver enhancement.