Radek Soukup

Organic based sensors: Novel screen printing technique for sensing layers deposition

This paper presents a research focused on development of low-cost manufacturing process which enables fabrication of accurate organic humidity sensors, where only screen printing is used for all layers deposition. It means that not only the interdigital structures with 50 μm line and space, but also phatolocynine sensing film and protective polymer layer are screen printed. The interdigital structures are printed by advanced screen printing in order to replace complex an expensive vacuum processes. In the frame of this research a novel screen printing technique for deposition of low viscose organic sensing film was also developed, where non-standard precise stainless steel Beta mesh was used for screens.

Smart textile-based protective system for firefighters

This paper presents a research focused on a smart textile-based protective system which is intended to bring more safety to firefighters facing hazardous conditions. The system is fully integrated into a firefighter protective suit and it is able to monitor heart rate (HR), to detect movements of a firefighter, to detect toxic and combustible gases in the environment and to measure temperature (T) and relative humidity (RH) inside and outside of the suit. The protective system consists of developed integrated sensor modules, e-textile wiring harnesses, body control unit (BCU), central processing unit (CPU), body area network (BAN) and wide area network (WAN). The measured data are wirelessly transmitted over a wide area network with automatic routing algorithm to the central processing unit, which is checked by a firefighter operation chief, who is kept informed about an actual state of individual fire fighters. In case that some monitored parameter oversteps pre-set threshold values the BCU will automatically inform a fire fighter by means of acoustic alarm about oncoming risk.

Perspective methods of creating conductive paths by Aerosol Jet Printing technology

This paper presents a research focused on four-wire resistivity measurement of the selected materials printed by Aerosol Jet Printing system (AJP) with different process parameters. The aerosol jet printing technology is an additive deposition technique which is based on the idea of the formation the aerosol mist from the printed ink and its transportation on the substrate by gas flow. The aerosol formation - the atomization process can be made by two different ways. One way is the pneumatic atomizer which smashes the ink on the wall of the jar and so creates the aerosol. The inks of viscosity from 1 to 1000 mPa·s can be used. The second way is the ultrasonic atomizer which creates the aerosol by smashing the ink by ultrasonic waves. In ultrasonic one, the viscosity of the ink should be in the range from 1 to 5 mPa·s. Three different conductive inks based on nanoparticles were printed to the form of the test pattern. Printing parameters were optimized in order to achieve highest conductivity of printed line. The impedance measurement and used inks are described in this paper. The main application of such aerosol jet printed materials could as follows: organic electro-chemical transistors (OECT), gas sensors, smart ID cards or RFID antennas.

Textile based temperature and humidity sensor elements for healthcare applications

This paper presents a research focused on embroidered temperature and humidity sensor elements for smart textile applications in health and medical care. Smart textile products face desirable textile properties for health care use include durability, “launderability” (washing resistance), flexibility and non-toxicity and the comfort aspect of clothing is also very important. For these reasons, the presented research was concentrated on the development of sensor elements based on specially prepared conductive yarns which are integrated into textile fabric with the familiar textile technique - embroidery and connected to control unit through snap fasteners. All the sensor element manufacturing steps are fully compatible with textile processing techniques. The preliminary investigation into the design, manufacturing and testing of the textile based temperature and humidity sensor elements are described in the paper.

A comparison of embroidered and woven textile electrodes for continuous measurement of ECG

This paper presents a research focused on comparison of two types of textile electrodes for continuous measurement of electrocardiogram (ECG) signals. We designed and realized knitted and embroidered textile electrodes, which were integrated in a sport top, chest strap and a functional T-shirt respectively. The integration of the electrodes was done in close cooperation of two SME textile companies. The knitted textrodes were made of silveR. STAT® and X-STATIC monofil continuous fibres. The fibres have a polyamide core coated with thin pure silver layer which makes them conductive, flexible, washable and anti-bacterial. The embroidered textrodes were realized from a developed high conductive hybrid thread. Object of this research are fully integrated and skin friendly embroidered and knitted electrodes, which will bring patients and convalescents more comfort and freedom. Medlab EG0500 module was used for ECG measurement and Raspberry Pi for data processing and communication.

Fast algorithm for evaluation of critical parameters of smart overalls

A fast and efficient algorithm is presented allowing a firefighter dressed in a smart firefighter protective suit continuously informing him about the time that he can still safely spend in a burning bulding, which is characterized by an dynamic environment of time-variable temperature. The algorithm starts from precalculated time evolution of temperature at selected places of the overall (mostly along its internal surface) for a number of values of the delivered external heat power that are then approximated by simple exponential functions. The prediction is then based on successive measurements of three or more temperatures in time and finding such a precalculated exponential function that best fits them. This function is important for predicting the maximum time of stay that is still safe for the firefighter in the current conditions.

Advanced screen printing for the fabrication of organic humidity sensors

This paper presents a research focused on development of an advanced screen printing technique for the fabrication of miniaturized, low-cost organic humidity sensors. According to the survey done by BCC Research the segment of temperature and humidity sensors achieved a worldwide turnover of 3.7 billion USD in 2010 and it represented 7 % of global sensor market [1]. Humidity sensors based on organic electronics can be used as diagnostic devices that may be implemented for diverse applications in environmental monitoring, rescue services, health and preventative medical care. The first stage of the research was focused on the advanced screen printing technique development, which could produce line and space widths below 50 μm and ultra-thin layer deposition well below 1 μm, in order to replace expensive and complex vacuum deposition methods and photolithography. The second stage of the research was focused on an organic humidity sensor element fabrication only by the developed screen printing processes. Screen printing is especially suitable due to its simplicity, low-cost, high reproducibility and efficiency in large-scale production.

A comparison of the interdigital electrodes prepared by aerosol jet printing and lift-off technique

This paper presents a research focused on a comparison of the quality and electrical parameters of the interdigital electrodes prepared by aerosol jet printing (AJP) technique and conventional lift-off technique. The Interdigital electrodes (IDE) belong among the most commonly used periodic electrode structures for a wide variety of sensors and transducers. The IDE testing sample were designed with line/space widths of 25 μm/25 μm and active area of 4.32 × 4.55 mm. The advantages of the aerosol jet printing technique over conventional techniques consist in the fact that: a) it can produce high-resolution patterns (down to a feature size of 8 μm × 8 μm), b) it is maskless additive technique, c) it is compatible with flexible or even 3D substrates and d) it is compatible with a very large range of inks. In the frame of the research Clariant nanoparticle silver ink, Fraunhofer IKTS nanoparticle gold ink were aerosol jet printed on flexible PET and Kapton® polyimide substrates. Electrical and geometrical parameters were measured for each substrate deposited by AJP technique. The measured data of all testing samples deposited by AJP were compared to the measured ones of the samples realized by the lift-off technique on the alumina substrate.

Defect level prediction for newly designed Printed Circuit Board Assemblies

In this paper a new defect level prediction tool is presented, which is intended for newly designed printed circuit board assemblies, especially for the PCBAs (Printed Circuit Board Assembly) determined for automotive industry. The tool is programmed in Visual Basic for Application (VBA) and can be operated in MS Excel environment.

Optimization of printed circuit board design assembly using yield prediction

The paper deals with optimization of printed circuit board design using yield prediction. Yield prediction of PCB assembly process can be obtained from the below presented yield model. The model is based on a combination of elements from two most used yield prediction methodologies, namely: process yield and board design yield. Due to PCB assembly process yield prediction is possible not only to assist the manufacturers in determining reliable estimates of production capabilities, but also to optimize PCB design process.