MSc A.S.M. Steijlen

1. A New Approach for Monitoring Sweat Ammonia Levels Using a Ventilated Capsule
   Annemarijn Steijlen; Jeroen Bastemaijer; Robbert Nederhoff; Kasper Jansen; Paddy French; Andre Bossche;
   engineering proceedings,
   Volume 38, pp. 6, 2021. DOI: https://doi.org/10.3390/ecsa-8-11332
   
   Keywords: ...

   sweat sensor; NH3; metal oxide gas sensor; ventilated capsule.
   
   
   Abstract: ...

   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 at 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 are integrated to compensate for temperature and humidity effects on the NH3 sensor.

2. Smart sensor tights: Movement tracking of the lower limbs in football
   Annemarijn Steijlen; Bastiaan Burgers; Erik Wilmes; Jeroen Bastemeijer; Bram Bastiaansen; Patrick French; Andre Bossche; Kaspar Jansen;
   Wearable technologies,
   Volume 2, 2021. DOI: 10.1017/wtc.2021.16
   
   Keywords: ...

   inertial measurement units, wearable sensors, football, movement tracking.
   
   
   Abstract: ...

   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 kinematic data of an optoelectronic measurement system and good validity (CMCs >0.8) was shown. In the field tests, participants experienced the tights as comfortable to wear and they did not feel restricted in their movements. These results show the potential of using the smart sensor tights on a regular base to derive lower limb kinematics in the field.

3. Smart sensor tights: Movement tracking of the lower limbs in football”, Wearable Technologies
   Annemarijn Steijlen; Bastiaan Burgers; Erik Wilmes; Jeroen Bastemeijer; Bram Bastiaansen; Patrick French; Andre Bossche; Kaspar Janse;
   Waerable Technologies,
   Volume 2, 2021. DOI: e17 doi:10.1017/wtc.2021.16

4. A wearable fluidic collection patch and ion chromatography method for sweat electrolyte monitoring during exercise
   Steijlen, Annemarijn SM; Bastemeijer, Jeroen; Groen, Pim; Jansen, Kaspar MB; French, Patrick J; Bossche, Andre;
   Analytical Methods,
   Volume 12, Issue 48, pp. 5885--5892, 2020. DOI: 10.1039/D0AY02014A
   
   Abstract: ...

   This paper presents a method to continuously collect and reliably measure sweat analyte concentrations during exercise. The method can be used to validate newly developed sweat sensors and to obtain insight into intraindividual variations of sweat analytes in athletes. First, a novel design of a sweat collection system is created. The sweat collection patch, that is made from hydrophilized foil and a double-sided acrylate adhesive, consists of a reservoir array that collects samples consecutively in time. During a physiological experiment, sweat can be collected from the back of a participant and the filling speed of the collector is monitored by using a camera. After the experiment, Na+, Cl− and K+ levels are measured with ion chromatography. Sweat analyte variations are measured during exercise for an hour at three different locations on the back. The Na+ and Cl− variations show a similar trend and the absolute concentrations vary with the patch location. Na+ and Cl− concentrations increase and K+ concentrations seem to decrease during this exercise. With this new sweat collection system, sweat Na+, Cl− and K+ concentrations can be collected over time during exercise at medium to high intensity, to analyse the trend in electrolyte variations per individual.

5. An Inertial Measurement Unit Based Method to Estimate Hip and Knee Joint Kinematics in Team Sport Athletes on the Field
   Bastiaansen, Bram JC; Wilmes, Erik; Brink, Michel S; de Ruiter, Cornelis J; Savelsbergh, Geert JP; Steijlen, Annemarijn; Jansen, Kaspar MB; van der Helm, Frans CT; Goedhart, Edwin A; van der Laan, Doris; others;
   JoVE (Journal of Visualized Experiments),
   Issue 159, pp. e60857, 2020. DOI: 10.3791/60857
   
   Abstract: ...

   Current athlete monitoring practice in team sports is mainly based on positional data measured by global positioning or local positioning systems. The disadvantage of these measurement systems is that they do not register lower extremity kinematics, which could be a useful measure for identifying injury-risk factors. Rapid development in sensor technology may overcome the limitations of the current measurement systems. With inertial measurement units (IMUs) securely fixed to body segments, sensor fusion algorithms and a biomechanical model, joint kinematics could be estimated. The main purpose of this article is to demonstrate a sensor setup for estimating hip and knee joint kinematics of team sport athletes in the field. Five male subjects (age 22.5 ± 2.1 years; body mass 77.0 ± 3.8 kg; height 184.3 ± 5.2 cm; training experience 15.3 ± 4.8 years) performed a maximal 30-meter linear sprint. Hip and knee joint angles and angular velocities were obtained by five IMUs placed on the pelvis, both thighs and both shanks. Hip angles ranged from 195° (± 8°) extension to 100.5° (± 8°) flexion and knee angles ranged from 168.6° (± 12°) minimal flexion and 62.8° (± 12°) maximal flexion. Furthermore, hip angular velocity ranged between 802.6 °·s-1 (± 192 °·s-1) and -674.9 °·s-1 (± 130 °·s-1). Knee angular velocity ranged between 1155.9 °·s-1 (± 200 °·s-1) and -1208.2 °·s-1 (± 264 °·s-1). The sensor setup has been validated and could provide additional information with regard to athlete monitoring in the field. This may help professionals in a daily sports setting to evaluate their training programs, aiming to reduce injury and optimize performance.

6. A novel sweat rate and conductivity sensor patch made with low-cost fabrication techniques
   Steijlen, ASM; Bastemeijer, J; Jansen, KMB; French, PJ; Bossche, A;
   In 2020 IEEE Sensors,
   IEEE, pp. 1--4, 2020. DOI: 10.1109/SENSORS47125.2020.9278850
   
   Abstract: ...

   Sweat sensor patches offer new opportunities for unobtrusive monitoring of an athlete's physical status. This paper presents a novel sweat rate and sweat conductivity patch that is easy to prototype and can be made with common low-cost production techniques: laser cutting and standard printed circuit board (PCB) manufacturing. The device consists of a patch made from hydrophilic PET foil, a double-sided adhesive and a thin PCB with gold electrodes. Two electrodes, which are continuously in contact with the inflowing fluid, measure the sweat conductivity and a separate system with interdigitated electrodes measures the filling process of the reservoirs. Impedance measurement results of both systems demonstrate the working of the concept.

7. Development of Sensor Tights with Integrated Inertial Measurement Units for Injury Prevention in Football
   Steijlen, ASM; Bastemeijer, J; Plaude, L; French, PJ; Bossche, A; Jansen, KMB;
   In Proceedings of the 6th International conference on Design4Health,
   2020.
   
   Abstract: ...

   In elite European football, 6 to 7 hamstring muscle injuries occur per team per season, which results in an absence of 14 to 180 days. These injuries occur typically in the last part of a training or match. This implies that the accumulation of demanding actions is an important factor for hamstring injury risk. In current practice, physical player load is measured at the field by deriving the global location of the player with GPS and RFID systems. However, these systems are not able to monitor leg movement and to distinguish demanding actions like kicking, cutting and jumping.In order to monitor these actions in the field, a novel design is being developed. The design consists of five sensor nodes with IMUs (Inertial measurement units), integrated in sports tights. IMUs can measure linear accelerations, angular velocities and magnetic fields in three directions. From these measurements, 3D kinematics of the lower limbs can be derived. An iterative design approach is used to develop the tights. Four prototypes will be developed. Each prototype is tested in a football specific setting, to identify areas of improvement from a technical point of view as well as from a user’s perspective. The final aim of this research is to develop sensor tights that can be worn unobtrusively by football players in the field. Real-time data are retrieved by the coach. This allows the coach to intervene when there is a high injury risk.

8. Development of a microfluidic collection system to measure electrolyte variations in sweat during exercise
   Steijlen, ASM; Bastemeijer, J; Groen, WA; Jansen, KMB; French, PJ; Bossche, A;
   In 2020 42nd Annual International Conference of the IEEE Engineering in Medicine \& Biology Society (EMBC),
   IEEE, pp. 4085--4088, 2020. DOI: 10.1109/EMBC44109.2020.9176123
   
   Abstract: ...

   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.

9. Analyzing sweat to determine state of fatigue
   Miguel Thomas; Andre Bossche; Pim Groen; Jeroen Bastemeijer; Annemarijn Steijlen; Paddy French;
   In Proceedings SSI conference,
   Barcelona, Spain, April 2019.

10. A Novel 12-Lead Electrocardiographic System for Home Use: Development and Usability Testing
    Annemarijn SM Steijlen; Kaspar MB Jansen; Armagan Albayrak; Derk O Verschure; Diederik F Van Wijk;
    JMIR mHealth and uHealth,
    Volume 6, Issue 7, pp. e10126, July 2018. DOI: 10.2196/10126
    
    Abstract: ...

    Background: Cardiovascular diseases (CVD) are the leading cause of morbidity and mortality worldwide. Early diagnosis is of pivotal importance for patients with cardiac arrhythmias and ischemia to minimize the consequences like strokes and myocardial infarctions. The chance of capturing signals of arrhythmias or ischemia is substantially high when a 12-lead electrocardiogram (ECG) can be recorded at the moment when a patient experiences the symptoms. However, until now, available diagnostic systems (Holter monitors and other wearable ECG sensors) have not enabled patients to record a reliable 12-lead ECG at home. Objective: The objective of this project was to develop a user-friendly system that enables persons with cardiac complaints to record a reliable 12-lead ECG at home to improve the diagnostic process and, consequently, reduce the time between the onset of symptoms and adequate treatment. Methods: Using an iterative design approach, ECGraph was developed. The system consists of an ECG measurement system and a mobile app, which were developed with the help of several concept tests. To evaluate the design, a prototype of the final design was built and a final technical performance test and usability test were executed. Results: The ECG measurement system consists of a belt and 4 limb straps. Ten wet Ag/AgCl electrodes are placed in the belt to optimize skin-electrode contact. The product is controlled via an app on the mobile phone of the user. Once a person experiences symptoms, he or she can put on the belt and record ECGs within a few minutes. Short instructions, supported by visualizations, offer guidance during use. ECGs are sent wirelessly to the caregiver, and the designated expert can quickly interpret the results. Usability tests with the final prototype (n=6) showed that the participants were able to put on the product within 8 minutes during first-time use. However, we expect that the placement of the product can be executed faster when the user becomes more familiar with the product. Areas of improvement focus mainly on confidence during product use. In the technical performance test, a 12-lead ECG was made and reproduced 6 times. Conclusions: We developed a new 12-lead ECG system for home use. The product is expected to be more user-friendly than current hospital ECG systems and is designed to record more reliable data than current ECG systems for home use, which makes it suitable for expert interpretation. The system has great potential to be incorporated into an outpatient practice, so that arrhythmias and ischemia can be diagnosed and treated as early as possible.

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