International Journal of Clothing Science and Technology
PurposeThe purpose of this study is to analyze the question “In what order of magnitude does the ... more PurposeThe purpose of this study is to analyze the question “In what order of magnitude does the comfort and performance improvement lie with the use of a cooling vest for construction workers?”.Design/methodology/approachThe use of personal cooling systems, in the form of cooling vests, is not only intended to reduce the heat load, in order to prevent disruption of the thermoregulation system of the body, but also to improve work performance. A calculation study was carried out on the basis of four validated mathematical models, namely a cooling vest model, a thermophysiological human model, a dynamic thermal sensation model and a performance loss model for construction workers.FindingsThe use of a cooling vest has a significant beneficial effect on the thermal sensation and the loss of performance, depending on the thermal load on the body.Research limitations/implicationsEach cooling vest can be characterized on the basis of the maximum cooling power (Pmax; in W/m²), the cooling ...
Adjunct Proceedings of the 2019 ACM International Joint Conference on Pervasive and Ubiquitous Computing and Proceedings of the 2019 ACM International Symposium on Wearable Computers
Eleven phase change materials (PCMs) for cooling humans in heat-stressed conditions were evaluate... more Eleven phase change materials (PCMs) for cooling humans in heat-stressed conditions were evaluated for their cooling characteristics. Effects of packaging material and segmentation were also investigated. Sample packs with a different type PCM (water- and oil-based PCMs, cooling gels, inorganic salts) or different packaging (aluminum, TPU, TPU + neoprene) were investigated on a hotplate. Cooling capacity, duration, and power were determined. Secondly, a PCM pack with hexagon compartments was compared to an unsegmented version with similar content. Cooling power decreased whereas cooling duration increased with increasing melting temperature. The water-based PCMs showed a >2x higher cooling power than other PCMs, but were relatively short-lived. The flexible gels and salts did not demonstrate a phase change plateau in cooling power, compromising their cooling potential. Using a TPU or aluminum packaging was indifferent. Adding neoprene considerably extended cooling duration, while...
ABSTRACT Injection molding is the most widely used processing technique for polymers. It offers s... more ABSTRACT Injection molding is the most widely used processing technique for polymers. It offers several advantages over other processing conditions such as good surface finish, the ability to process complex parts without the need of secondary operations, and low cost for mass production. However, because of the complex deformation, and thermal and pressure histories that the polymer melt experiences during processing, residual stresses develop. These stresses act internally at room temperature and have the same effects on the material as externally applied stresses do, resulting in shrinkage and warpage of the product. In recent years, with the development and use of engineering plastics in an increasing number of applications, and with the tougher quality control policies in industries such as the automotive, the effects of residual stresses in product quality and performance have raised great interest. This review reports up-to-date advances in the field of residual stresses developments in polymers, with special attention given to injection molded products. Flow- and thermal-induced residual stresses are reported. Emphasis is given to the processing parameters that most influence residual stresses during injection molding as well as the effect of residual stresses not only on warpage but also on other material properties.
This article presents a novel smart sensor garment with integrated miniaturized inertial measurem... more This article presents a novel smart sensor garment with integrated miniaturized inertial measurements units (IMUs) that can be used to monitor lower body kinematics during daily training activities, without the need of extensive technical assistance throughout the measurements. The smart sensor tights enclose five ultra-light sensor modules that measure linear accelerations, angular velocities, and the earth magnetic field in three directions. The modules are located at the pelvis, thighs, and shanks. The garment enables continuous measurement in the field at high sample rates (250 Hz) and the sensors have a large measurement range (32 g, 4,000°/s). They are read out by a central processing unit through an SPI bus, and connected to a centralized battery in the waistband. A fully functioning prototype was built to perform validation studies in a lab setting and in a field setting. In the lab validation study, the IMU data (converted to limb orientation data) were compared with the ki...
Cooling vests containing phase change materials (PCMs) are used to reduce heat stress in hot envi... more Cooling vests containing phase change materials (PCMs) are used to reduce heat stress in hot environments and maintain the body core temperature within a safe range. The performance of such cooling vests depends in a complicated way on the PCM material and mass, the insulation value of the clothing layers and heat loss to the environment. Conventionally, these performance parameters are evaluated experimentally or using a numerical model, both of which do need a certain amount of evaluation time. The objective of this paper is to develop a transient heat transfer model which includes metabolic heat production in the human body, as well as clothing and PCM layers and radiation to the environment but which is presented as a series of closed-form equations that can be evaluated without the need of a numerical solver. We present solutions for the body and PCM temperature as well as for the heat flux, cooling power and cooling duration. The model equations are validated by comparing them...
Action statistics in sports, such as the number of sprints and jumps, along with the details of t... more Action statistics in sports, such as the number of sprints and jumps, along with the details of the corresponding locomotor actions, are of high interest to coaches and players, as well as medical staff. Current video-based systems have the disadvantage that they are costly and not easily transportable to new locations. In this study, we investigated the possibility to extract these statistics from acceleration sensor data generated by a previously developed sensor garment. We used deep learning-based models to recognize five football-related activities (jogging, sprinting, passing, shooting and jumping) in an accurate, robust, and fast manner. A combination of convolutional (CNN) layers followed by recurrent (bidirectional) LSTM layers achieved up to 98.3% of accuracy. Our results showed that deep learning models performed better in evaluation time and prediction accuracy than traditional machine learning algorithms. In addition to an increase in accuracy, the proposed deep learnin...
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.
The purpose of this study is to simulate the two-dimensional, transient and continuous heat trans... more The purpose of this study is to simulate the two-dimensional, transient and continuous heat transfer during the thermoset Automated Tape Laying (ATL) process. The heat transfer analysis is coupled with a cure kinetics model of the thermoset prepreg tapes used for the process. Unlike most studies, the process is modelled in a Lagrangian framework and is based on the realistic boundary conditions of the ATL such as the stepwise laying down of the tapes. The model results provide information about the temperature values at any time and any location inside the thermoset composite tapes. The temperature simulation results of the model were compared with experiments. Three layers of unidirectional prepreg tapes were laid down on an aluminium mould by the TU Delft ATL machine. The experimental results were obtained from thermocouples and pyrometers placed at various locations in the lay-up and on the robotic head, respectively. The comparison between the numerical and experimental results ...
2020 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), 2020
A wide variety of electrochemical sweat sensors are recently being developed for real-time monito... more A wide variety of electrochemical sweat sensors are recently being developed for real-time monitoring of biomarkers. However, from a physiological perspective, little is known about how sweat biomarkers change over time. This paper presents a method to collect and analyze sweat to identify inter and intraindividual variations of electrolytes during exercise. A new microfluidic sweat collection system is developed which consists of a patch covering the collection surface and a sequence of reservoirs. Na+, Cl- and K+ are measured with ion chromatography afterwards. The measurements show that with the new collector, variations in these ion concentrations can be measured reliably over time.
Proceedings of the 2017 ACM Conference Companion Publication on Designing Interactive Systems, 2017
In this paper we investigate how autonomy, animism and presence of interactive products in daily ... more In this paper we investigate how autonomy, animism and presence of interactive products in daily life can positively influence people to change their behavior. Three interactive products were reviewed and compared on each of these concepts. Based on this comparison we propose that a product's autonomy is a prerequisite to initiate behavior change when people are unwilling, unable or unware to act, while animism creates a sense of social engagement between user and product. Presence refers to the availability and readiness of a product to engage people on a daily basis. We conclude with discussing the potentiality of these concepts in developing an integrated design strategy for behavior change.
Communications in Development and Assembling of Textile Products, 2021
Prolonged exposure to solar radiation can cause considerable heat stress. The application of refl... more Prolonged exposure to solar radiation can cause considerable heat stress. The application of reflective materials in garments or sunscreens is generally considered as an appropriate protective strategy. In this study, we aimed to compare a range of reflective and control fabrics on their ability to reduce the thermal impact of solar radiation. We evaluated 16 reflective and 5 control fabrics, varying in applicability for garments and/or sunscreens. Transmission of ultraviolet, visible light and infrared radiation was studied using artificial solar light. Thermal impact reduction was first studied using artificial infrared light and secondly using natural sunlight, measuring temperature right at the back and 10 cm behind the fabric after a 10-minute exposure. Most samples showed comparably low radiation transmission (<10%). However, substantially higher transmission was observed in perforated and mesh-like reflective fabrics, as well as light-colored controls and coldblack® treate...
By embedding conductive yarns in, or onto, knitted textile fabrics, simple but robust stretch sen... more By embedding conductive yarns in, or onto, knitted textile fabrics, simple but robust stretch sensor garments can be manufactured. In that way resistance based sensors can be fully integrated in textiles without compromising wearing comfort, stretchiness, washability, and ease of use in daily life. The many studies on such textile strain sensors that have been published in recent years show that these sensors work in principle, but closer inspection reveals that many of them still have severe practical limitations like a too narrow working range, lack of sensitivity, and undesired time-dependent and hysteresis effects. For those that intend to use this technology it is difficult to determine which manufacturing parameters, shape, stitch type, and materials to apply to realize a functional sensor for a given application. This paper therefore aims to serve as a guideline for the fashion designers, electronic engineers, textile researchers, movement scientists, and human–computer inter...
Advances in Engineering Materials, Structures and Systems: Innovations, Mechanics and Applications, 2019
This paper presents a new strategy to control the structure dynamic response via a shift of the n... more This paper presents a new strategy to control the structure dynamic response via a shift of the natural frequencies obtained through using variable stiffness joints. The joints are made of shape memory pol-ymers and are fabricated through 3D printing. Stiffness variation is activated through resistive heating which causes a phase change from a glassy to a rubbery state in order to switch the joint between a ‘locked’ (e.g. a moment connection) and a ‘released’ (e.g. pin) state. This work comprises an experimental and a numerical part: 1) dynamic mechanical thermal analysis (DMTA) has been carried out to characterize the viscoelastic behavior of a 3D printed SMP specimen; 2) the dynamic response of a 2-floor planar frame equipped with four variable stiffness SMP joints is simulated through transient analysis. Numerical results show that through joint stiffness control, the fundamental frequency shifts up to 19% causing a drastic reduction of the dynamic re-sponse under resonance loading. A comparison between variable stiffness joints with viscoelastic and only-elastic behavior shows that viscoelasticity increases mechanical damping up to 4.7 times during the transition phase.
International Journal of Clothing Science and Technology
PurposeThe purpose of this study is to analyze the question “In what order of magnitude does the ... more PurposeThe purpose of this study is to analyze the question “In what order of magnitude does the comfort and performance improvement lie with the use of a cooling vest for construction workers?”.Design/methodology/approachThe use of personal cooling systems, in the form of cooling vests, is not only intended to reduce the heat load, in order to prevent disruption of the thermoregulation system of the body, but also to improve work performance. A calculation study was carried out on the basis of four validated mathematical models, namely a cooling vest model, a thermophysiological human model, a dynamic thermal sensation model and a performance loss model for construction workers.FindingsThe use of a cooling vest has a significant beneficial effect on the thermal sensation and the loss of performance, depending on the thermal load on the body.Research limitations/implicationsEach cooling vest can be characterized on the basis of the maximum cooling power (Pmax; in W/m²), the cooling ...
Adjunct Proceedings of the 2019 ACM International Joint Conference on Pervasive and Ubiquitous Computing and Proceedings of the 2019 ACM International Symposium on Wearable Computers
Eleven phase change materials (PCMs) for cooling humans in heat-stressed conditions were evaluate... more Eleven phase change materials (PCMs) for cooling humans in heat-stressed conditions were evaluated for their cooling characteristics. Effects of packaging material and segmentation were also investigated. Sample packs with a different type PCM (water- and oil-based PCMs, cooling gels, inorganic salts) or different packaging (aluminum, TPU, TPU + neoprene) were investigated on a hotplate. Cooling capacity, duration, and power were determined. Secondly, a PCM pack with hexagon compartments was compared to an unsegmented version with similar content. Cooling power decreased whereas cooling duration increased with increasing melting temperature. The water-based PCMs showed a >2x higher cooling power than other PCMs, but were relatively short-lived. The flexible gels and salts did not demonstrate a phase change plateau in cooling power, compromising their cooling potential. Using a TPU or aluminum packaging was indifferent. Adding neoprene considerably extended cooling duration, while...
ABSTRACT Injection molding is the most widely used processing technique for polymers. It offers s... more ABSTRACT Injection molding is the most widely used processing technique for polymers. It offers several advantages over other processing conditions such as good surface finish, the ability to process complex parts without the need of secondary operations, and low cost for mass production. However, because of the complex deformation, and thermal and pressure histories that the polymer melt experiences during processing, residual stresses develop. These stresses act internally at room temperature and have the same effects on the material as externally applied stresses do, resulting in shrinkage and warpage of the product. In recent years, with the development and use of engineering plastics in an increasing number of applications, and with the tougher quality control policies in industries such as the automotive, the effects of residual stresses in product quality and performance have raised great interest. This review reports up-to-date advances in the field of residual stresses developments in polymers, with special attention given to injection molded products. Flow- and thermal-induced residual stresses are reported. Emphasis is given to the processing parameters that most influence residual stresses during injection molding as well as the effect of residual stresses not only on warpage but also on other material properties.
This article presents a novel smart sensor garment with integrated miniaturized inertial measurem... more This article presents a novel smart sensor garment with integrated miniaturized inertial measurements units (IMUs) that can be used to monitor lower body kinematics during daily training activities, without the need of extensive technical assistance throughout the measurements. The smart sensor tights enclose five ultra-light sensor modules that measure linear accelerations, angular velocities, and the earth magnetic field in three directions. The modules are located at the pelvis, thighs, and shanks. The garment enables continuous measurement in the field at high sample rates (250 Hz) and the sensors have a large measurement range (32 g, 4,000°/s). They are read out by a central processing unit through an SPI bus, and connected to a centralized battery in the waistband. A fully functioning prototype was built to perform validation studies in a lab setting and in a field setting. In the lab validation study, the IMU data (converted to limb orientation data) were compared with the ki...
Cooling vests containing phase change materials (PCMs) are used to reduce heat stress in hot envi... more Cooling vests containing phase change materials (PCMs) are used to reduce heat stress in hot environments and maintain the body core temperature within a safe range. The performance of such cooling vests depends in a complicated way on the PCM material and mass, the insulation value of the clothing layers and heat loss to the environment. Conventionally, these performance parameters are evaluated experimentally or using a numerical model, both of which do need a certain amount of evaluation time. The objective of this paper is to develop a transient heat transfer model which includes metabolic heat production in the human body, as well as clothing and PCM layers and radiation to the environment but which is presented as a series of closed-form equations that can be evaluated without the need of a numerical solver. We present solutions for the body and PCM temperature as well as for the heat flux, cooling power and cooling duration. The model equations are validated by comparing them...
Action statistics in sports, such as the number of sprints and jumps, along with the details of t... more Action statistics in sports, such as the number of sprints and jumps, along with the details of the corresponding locomotor actions, are of high interest to coaches and players, as well as medical staff. Current video-based systems have the disadvantage that they are costly and not easily transportable to new locations. In this study, we investigated the possibility to extract these statistics from acceleration sensor data generated by a previously developed sensor garment. We used deep learning-based models to recognize five football-related activities (jogging, sprinting, passing, shooting and jumping) in an accurate, robust, and fast manner. A combination of convolutional (CNN) layers followed by recurrent (bidirectional) LSTM layers achieved up to 98.3% of accuracy. Our results showed that deep learning models performed better in evaluation time and prediction accuracy than traditional machine learning algorithms. In addition to an increase in accuracy, the proposed deep learnin...
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.
The purpose of this study is to simulate the two-dimensional, transient and continuous heat trans... more The purpose of this study is to simulate the two-dimensional, transient and continuous heat transfer during the thermoset Automated Tape Laying (ATL) process. The heat transfer analysis is coupled with a cure kinetics model of the thermoset prepreg tapes used for the process. Unlike most studies, the process is modelled in a Lagrangian framework and is based on the realistic boundary conditions of the ATL such as the stepwise laying down of the tapes. The model results provide information about the temperature values at any time and any location inside the thermoset composite tapes. The temperature simulation results of the model were compared with experiments. Three layers of unidirectional prepreg tapes were laid down on an aluminium mould by the TU Delft ATL machine. The experimental results were obtained from thermocouples and pyrometers placed at various locations in the lay-up and on the robotic head, respectively. The comparison between the numerical and experimental results ...
2020 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), 2020
A wide variety of electrochemical sweat sensors are recently being developed for real-time monito... more A wide variety of electrochemical sweat sensors are recently being developed for real-time monitoring of biomarkers. However, from a physiological perspective, little is known about how sweat biomarkers change over time. This paper presents a method to collect and analyze sweat to identify inter and intraindividual variations of electrolytes during exercise. A new microfluidic sweat collection system is developed which consists of a patch covering the collection surface and a sequence of reservoirs. Na+, Cl- and K+ are measured with ion chromatography afterwards. The measurements show that with the new collector, variations in these ion concentrations can be measured reliably over time.
Proceedings of the 2017 ACM Conference Companion Publication on Designing Interactive Systems, 2017
In this paper we investigate how autonomy, animism and presence of interactive products in daily ... more In this paper we investigate how autonomy, animism and presence of interactive products in daily life can positively influence people to change their behavior. Three interactive products were reviewed and compared on each of these concepts. Based on this comparison we propose that a product's autonomy is a prerequisite to initiate behavior change when people are unwilling, unable or unware to act, while animism creates a sense of social engagement between user and product. Presence refers to the availability and readiness of a product to engage people on a daily basis. We conclude with discussing the potentiality of these concepts in developing an integrated design strategy for behavior change.
Communications in Development and Assembling of Textile Products, 2021
Prolonged exposure to solar radiation can cause considerable heat stress. The application of refl... more Prolonged exposure to solar radiation can cause considerable heat stress. The application of reflective materials in garments or sunscreens is generally considered as an appropriate protective strategy. In this study, we aimed to compare a range of reflective and control fabrics on their ability to reduce the thermal impact of solar radiation. We evaluated 16 reflective and 5 control fabrics, varying in applicability for garments and/or sunscreens. Transmission of ultraviolet, visible light and infrared radiation was studied using artificial solar light. Thermal impact reduction was first studied using artificial infrared light and secondly using natural sunlight, measuring temperature right at the back and 10 cm behind the fabric after a 10-minute exposure. Most samples showed comparably low radiation transmission (<10%). However, substantially higher transmission was observed in perforated and mesh-like reflective fabrics, as well as light-colored controls and coldblack® treate...
By embedding conductive yarns in, or onto, knitted textile fabrics, simple but robust stretch sen... more By embedding conductive yarns in, or onto, knitted textile fabrics, simple but robust stretch sensor garments can be manufactured. In that way resistance based sensors can be fully integrated in textiles without compromising wearing comfort, stretchiness, washability, and ease of use in daily life. The many studies on such textile strain sensors that have been published in recent years show that these sensors work in principle, but closer inspection reveals that many of them still have severe practical limitations like a too narrow working range, lack of sensitivity, and undesired time-dependent and hysteresis effects. For those that intend to use this technology it is difficult to determine which manufacturing parameters, shape, stitch type, and materials to apply to realize a functional sensor for a given application. This paper therefore aims to serve as a guideline for the fashion designers, electronic engineers, textile researchers, movement scientists, and human–computer inter...
Advances in Engineering Materials, Structures and Systems: Innovations, Mechanics and Applications, 2019
This paper presents a new strategy to control the structure dynamic response via a shift of the n... more This paper presents a new strategy to control the structure dynamic response via a shift of the natural frequencies obtained through using variable stiffness joints. The joints are made of shape memory pol-ymers and are fabricated through 3D printing. Stiffness variation is activated through resistive heating which causes a phase change from a glassy to a rubbery state in order to switch the joint between a ‘locked’ (e.g. a moment connection) and a ‘released’ (e.g. pin) state. This work comprises an experimental and a numerical part: 1) dynamic mechanical thermal analysis (DMTA) has been carried out to characterize the viscoelastic behavior of a 3D printed SMP specimen; 2) the dynamic response of a 2-floor planar frame equipped with four variable stiffness SMP joints is simulated through transient analysis. Numerical results show that through joint stiffness control, the fundamental frequency shifts up to 19% causing a drastic reduction of the dynamic re-sponse under resonance loading. A comparison between variable stiffness joints with viscoelastic and only-elastic behavior shows that viscoelasticity increases mechanical damping up to 4.7 times during the transition phase.
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Papers by Kaspar Jansen