Tadeusz Pisarkiewicz

A Micropreconcentrator Design Using Low Temperature Cofired Ceramics Technology for Acetone Detection Applications

We design and manufacture the gas micropreconcentrator in low temperature cofired ceramics (LTCC) technology. The structure is 1.2-mm thick and has lateral dimensions of 25 × 20 mm. It consists of eight layers of LTCC green tapes with spiral-shaped channel filled with absorbing powder. Two heaters covered by the ceramic foils are embedded over and below the channel. The heaters are required for heating the adsorbent to elevated temperatures during its activation and desorption processes. In this paper, we describe the fabrication processes of a micropreconcentrator structure designed for acetone detection applications together with thermal and preconcentration measurements of the device. Commercially available adsorbents: Carboxen-1018, Carboxen-1012, and Carboxen-1003 from Sigma-Aldrich are selected and tested in order to concentrate low levels of acetone. The best concentration factor obtained is 5250.

Performance of Si-Doped WO 3 Thin Films for Acetone Sensing Prepared by Glancing Angle DC Magnetron Sputtering

This paper presents the acetone sensing characteristics of Si-doped (1 at.%) tungsten oxide thin films prepared by glancing angle dc magnetron sputtering. The performance of Si-doped WO3 sensors in the concentration range of 0.04-3.8 ppm at operating temperatures of 150 °C-425 °C has been investigated. Doping of the tungsten oxide film with Si significantly decreases the limit of detection of acetone compared with the pure WO3 sensors reported in the literature. The gas sensors response (S) to acetone was defined as the resistance ratio S = Rair/Rgas, where Rair and Rgas are the electrical resistances for the sensor in air and in gas, respectively. The maximum response measured in this experiment was S = 40.5. Such response was measured in the presence of 3.8 ppm of acetone at an operating temperature of 425 °C using a Si-doped (1 at.%) WO3 thin film deposited at 300 °C and annealed at 300 °C for 4 h in air. The films phase composition, microstructure, and surface topography have been assessed by X-ray diffraction, scanning electron microscope, atomic force microscope, and energy dispersive X-ray spectroscopy methods.

Nano-thin CuO films doped with Au and Pd for gas sensors applications

The cupric oxide (CuO) thin films are promising materials in gas sensor applications. The CuO exhibits the highest sensitivity for hydrogen sulfide, but it may be also used as a sensor for carbon monoxide or nitrogen dioxide. The sensitivity and long-term stability are critical issues in gas sensor applications. The authors present the results of investigation on nano-thin film of CuO and CuO doped with Au and Pd. The films were deposited in magnetron sputtering technology on LTCC substrates. The results of gas sensor response are presented and discussed. The long-term stability test were performed.

Metal oxide nanostructures for gas detection

Currently, most of gas sensors on the market are produced in thin or thick film technologies with the use of ceramic substrates. It is expected that the miniature sensors needed in portable applications will be based on one-dimensional structures due to their low power consumption, fast and stable time response, small dimensions and possibility of embedding in integrated circuit together with signal conditioning electronics. The authors manufactured resistance type gas sensors based on ZnO and WO3 nanostructures. ZnO:Al nanorods with good cristallinity were obtained with electrodeposition method, while ZnO:Al nanofibres with varying diameters were obtained by electrospinning method. The sensors were built as a nanowire network. WO3 films with nanocrystalline surface were manufactured by deposition of a three layer WO3/W/WO3 structure by RF sputtering and successive annealing of the structure in appropriate temperature range. In effect a uniform nanostructurized metal oxide layer was formed. Investigation of sensors characteristics revealed good sensitivity to nitrogen dioxide at temperatures lower than these for conventional conductometric type sensors.

Detection of acetone in exhaled breath with the use of micropreconcentrator and a commercial gas sensor

This paper presents investigation results obtained with the measuring system enabling detection of acetone with concentrations lower than 1 ppm. In the experiment we used both conventional preconcentrators made from materials such as stainless steel and quartz tubes and a micropreconcentrator manufactured in MEMS technology. The active volume of all preconcentrators was equal to enable comparisons of their performance. As a gas detector at the output of the measurement system we used both commercial semiconductor gas sensor and a mass spectrometer for comparison purposes. The obtained results show that the measurement system with micropreconcentrator and a commercial gas sensor can be used for detection of low level acetone present in the air exhaled by diabetics.

Electron Technology: ELTE 2016

In this paper we present a review of research results and technical accomplishments presented by researchers from technical universities, governmental institutes and research companies during the XIIth Scientific Conference Electron Technology, ELTE 2016. This review is based on materials presented at four topical conference sessions: Microelectronics and Nanoelectronics, Photonics, Materials and Technologies, and Microsystems and also on materials presented by invited speakers at two dedicated sessions. Oral sessions were accompanied by the poster sessions. In effect about 50 papers gathered in this volume reflect the topics discussed at the Conference. A short description of technological and measurement possibilities in the laboratories of Academic Centre for Materials and Nanotechnology and also in the Department of Electronics of the Faculty of Computer Science, Electronics and Telecommunications AGH UST are given.

Sensor properties of ZnO:Al nanofibres obtained by electrospinning

An electrospinning technology have been developed to obtain zinc oxide nanofibres doped with aluminum. Properties of the obtained nanostructures can be controlled by both the composition of a precursor and subsequent annealing treatment. The gas sensors manufactured with the use of ZnO:Al nanofibres exhibit good response to NO2 at relatively low operating temperatures. For some samples it was observed that interaction with ambient NO2 gas causes the change of conductivity from n-type to p-type at higher operating temperatures. This phenomenon was not observed for the samples annealed at higher temperature.

The gas micropreconcentrators in LTCC and MEMS technologies for breath acetone analysis

The authors designed and manufactured the gas micropreconcentrators in two of the most popular industry technologies: low temperature cofired ceramic (LTCC) and microelectromechanical systems (MEMS). Both structures have similar lateral dimensions: 20 mm × 25 mm × 1.2 mm for micropreconcentrator in LTCC technology and 20 mm × 20 mm × 1.68 mm for micropreconcentrator in MEMS technology. Both structures contain a 120 mm long channel filled with adsorbent material. The authors used commercially available adsorbents supplied by Sigma-Aldrich. In the paper the authors describe thermal measurements, power consumption and concentration factor tests of manufactured structures for gaseous acetone.

Rapid temperature processing (RTP) system for selenization of photovoltaic materials

Rapid Temperature Processing (RTP) methodology is widely applied in thin-film photovoltaic materials technology due to high quality of fabricated cells and also perspectives for their mass manufacturing. This paper describes a RTP device structure which contains the graphite reactor for selenization of Cu/In or Cu/In/Se precursors. Strong nonlinearity of radiative energy transfer makes RTP controlling difficult so it still needs to be improved. Using mathematical model of the device, we are proposing the method of process controlling. Experimentally obtained temperature profiles of Rapid Temperature Processes are presented and compared with temperature profile of typical CIS selenization graphite reactor. Presented steering procedure, based on our model, gives improves by decreasing time needed for selenization and simultaneously reducing costs of the process.

Influence of gas microsensor mounting technique on its temperature time constant

Metal oxide semiconductor gas sensors with modulated working temperature should reveal small thermal time constant in comparison to the time constants of chemical reactions between gas atmosphere and sensitive layer. In such case analyzed sensor response is dominated with specific phenomena originated from these reactions. A way the sensors are mounted has big influence on the sensor thermal time constants. In experiments authors used gas sensors with ceramic and micromachined silicon substrates glued to the case or suspended on thin wires. Although mechanical stability and durability of glued sensors are better, the lower power consumption and lower time constants are possible with sensors mounted using thin wires.