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Aims: A PCR technique was developed as a reliable and rapid identification method for the Bacillus cereus group species, based on a unique conserved sequence of the motB gene (encoding flagellar motor protein) from B. cereus, Bacillus thuringiensis and Bacillus anthracis. Methods and Results: Primer locations were identified against eight strains of the B. cereus group spp. from nucleotide sequences available in the National Centre for Biotechnology Information database. The PCR assay was applied for the identification of 117 strains of the B. cereus group spp. and 19 strains from other microbial species, with special emphasis on foodborne pathogens. Conclusion: The designed cross-species primers are group specific and did not react with DNA from other Bacillus and non-Bacillus species either motile or not. The primers system enabled us to detect 103 CFU of B. cereus cells per millilitre of sample. Significance and Impact of the Study: Bacillus cereus group spp. belongs to one of the most prevalent foodborne pathogens. Bacterial growth results in production of different toxins; therefore, consumption of food containing >106 bacteria per gram may result in emetic and diarrhoeal syndromes. A rapid and sensitive bacterial detection method is significant for food safety.

Interdigitated capacitors have the potential to be used in pressure sensing applications requiring small size, high reliability and cost effective production. Such sensors have applications in wireless pressure monitoring of bodily fluids for the research and diagnosis of a number of medical conditions in cardiology, pulmonology and gastroenterology. In this work, the sensitivity of Polyvinyl Butyral (PVB)/carbon-black composites to pressure is evaluated with these applications in mind. The devices are fabricated by drop coating solutions containing PVB and 5, 10, 15 and 20% carbon black onto interdigitated electrodes. The optimum carbon loading for pressure sensing applications up to 2500 kPa was determined for these composites using a tensile tester. The highest sensitivity was recorded for samples with 5% carbon black. These devices were successfully integrated into a prototype wireless interface, transmitter and receiver system. The response (25 mV), hysteresis (4.78%) and repeatability (10.76%) under hydrostatic pressure ranging from 0–17 kPa were measured. Finally, the devices temperature dependence was investigated.

Accurate pressure readings are essential tools in a wide range of applications. For example in monitoring intracranial pressure for patients with head injuries or tyre pressure to improve automobile safety. With this in mind, a real time monitoring system, which displays the change in sensor capacitance with pressure on a PC, has been developed. Thick film capacitors with an oxide dielectric layer formed using niobium pentoxide (Nb 2 O 5 ), titanium dioxide (TiO 2 ) and cerium dioxide (CeO 2 ) are investigated using this system. SEM was used to examine the morphology and particle size of the thick films. To aid in the development of a suitable interface circuitry, the frequency and temperature dependence of each device is investigated. Each sensor was then subjected to pressures in the region of 0–100 kPa. The results show that capacitors with an Nb 2 O 5 dielectric layer were most sensitive. It is thought that this is due to its particle size.

Remote pressure monitoring is of particular importance in medical and environmental applications as it is less labour intensive, safer and offers peace of mind to the general public. To meet this demand, a prototype system has been developed and used to evaluate thick-film pressure sensors with an oxide dielectric layer. The circuit is based on the principle of capacitance-frequency-voltage conversion and has been designed to minimize power consumption. Each device was tested under hydrostatic pressure in the range 0-17 kPa and assessed in terms of sensitivity, hysteresis, repeatability, creep and temperature effects. The results show that this approach may be used for the fabrication of cost effective, reliable devices for wireless pressure sensing applications

Presented are the results of investigations of the effects of organic solvent vapours and excess noise measurements on drop-coated poly(vinyl butyral)\carbon black nanocomposite gas sensitive resistors. The devices were shown to exhibit significant resistance changes upon exposure to methanol, propanol and particularly hexanol vapours in the concentration range 1000 to 5000 ppm. The effects of the organic solvent vapours on the noise power spectra of the PVB\CB sensors were also investigated, but results were found to yield no information surplus to that of the DC sensor signal. The large values of 1/f noise observed were attributed to inhomogeneity and discontinuity of the deposited sensing layer. The discontinuity of the drop-coated layer was subsequently confirmed by SEM micrographs of the samples.

In this work, screen-printing onto glass and polymer substrates was used to form capacitors with an active area of 2 × 3 mm2. The dielectric was formed using a polymer paste with TiO2 as the functional ingredient. Devices prepared on glass substrates were tested as strain gauges. Their GF was measured to be 30. This is higher than the standard values (3–15) recorded for gauges based on oxide materials. It is thought that the higher sensitivity is a result of the preparation method and small crystallite size of the TiO2 powder. After quantifying the materials sensitivity, the sensors on polymer substrates were attached to planar and cylindrical surfaces. They were then incorporated into a wireless pressure measurement system, consisting of a small size interface circuit and a transmitter. The receiver outputs a voltage reading corresponding to the sensor capacitance. Each device was placed in a liquid environment so that it could be exposed to hydrostatic pressure. A high sensitivity to pressure changes with low hysteresis was observed. It is thought that this system could be used to wirelessly monitor pressure changes in a variety of difficult to reach environments.

Presented are the results of excess noise measurements on poly(vinyl butyral)\carbon black nanocomposite gas sensitive resistors. The devices were prepared by a drop-coating technique in which a microlitre syringe was used to deposit the materials onto Cu thin-film parallel electrodes. Noise power spectra of the devices under bias currents ranging from 80 to 150 μA were obtained. The detection limits were found to be 6.3 ppm, 5.2 ppm and 68 ppb for methanol, propanol and hexanol vapour, respectively. The noise index was also evaluated for the devices, with a value of approximately 29 dB being measured.

This paper investigates the use of iron and zinc oxide thick film materials, screen-printed onto glass substrates with silver electrodes. The sensor was interfaced with three resistors to form a bridge circuit. This was then used to detect methanol, ethanol and propanol vapours within a concentration range of 0–3000 ppm. The sensitivity of the sensor is defined as the change in bridge output voltage (mV) per change in gas concentration (ppm). The sensitivity of the sensor to 3000 ppm methanol, ethanol and propanol at room temperature was 3.5, 6.6, 22 μV/ppm while the relative resistance change of the sensor was calculated as (Δ R / R ) × 100 and was 0.84, 2.5 and 5.2, respectively. The device exhibited the highest sensitivity to propanol, followed by ethanol and methanol, respectively. The recorded sensitivity decreased when the temperature was increased from room temperature 25 to 65 °C. The response/recovery times of the sensor to 1000 ppm propanol were seen to improve with increased temperature, being 45/90 s at 25 °C and 22.5/45 s at 65 °C.

The cruel reality of today's world forces mankind to be alert and prepared for all kinds of terrorist threats, including exposure to radiation. There is a need for cost-effective alternatives to existing commercially available real-time gamma radiation dosimeters. In this paper, numerous oxides such as NiO, CeO/sub 2/, TeO/sub 2/, In/sub 2/O/sub 3/, SiO, MnO, etc., and their mixtures in different proportions were used as the basis for such a substitute. Thin- and thick-film devices were made in the form of resistors and capacitors, structures with interdigitated electrodes, and pn-junctions. These, in different mixtures, were found to change their sensitivity when exposed to /spl gamma/-rays. In general, thin-film devices were found to be more sensitive to lower doses of radiation than the counterpart thick films. However, it was experimentally demonstrated that it is possible to fabricate a device that would satisfy the requirement of a particular application, such as the sensitivity to /spl gamma/-radiation exposure and working dose regions. Based on the above data, these structures might be regarded as a cost-effective alternative for room-temperature real-time /spl gamma/-radiation dosimetry.

In this work the strain sensing properties of interdigitated and sandwich thick film capacitors, using titanium dioxide as the dielectric, are investigated. By pre-firing the TiO 2 powder and forming a polymer thick film paste the use of expensive paste ingredients, such as ruthenium or palladium oxide, was avoided. After firing, XRD was used to verify the composition and crystallite size of the TiO 2 powder, while SEM allowed the particle sizes of the powder to be examined. It was found that the powder has a crystallite and particle size, which is less than 1 μm. Following this, the sensors were fabricated by screen-printing onto glass substrates and placed in a cantilever beam arrangement so that the change in their capacitance with strain could be measured. The gauge factor, which demonstrates the devices sensitivity, was found by dividing the fractional change in capacitance by the applied strain. A gauge factor of 5 and 30 was recorded for interdigitated and sandwich capacitors, respectively. In the case of sandwich capacitors, this gauge factor is higher than normally achieved using oxide films (3–15). Furthermore, the sensors showed a high degree of linearity with low hysteresis. The TCC has been measured for temperatures ranging from 25 to 70 °C so that the effect of temperature on the devices is known. Values, typical of thick film capacitors (876–2834 ppm/°C) have been recorded for temperatures up to 60 °C. Finally, ac electrical measurements have been used to shown that tunnelling is the dominant conduction mechanism within the TiO 2 film.

Investigations into γ-radiation-induced changes in the electrical properties of CeO2 thick films of various structures were carried out for dosimetry purposes. The detection of radiation was based on the fact, that properties of the materials undergo changes upon the influence of γ-radiation. Carbon doping was used to control the resistivity of the CeO2 polymer thick films. Screen-printed capacitors, resistors and pn-junctions were exposed to a disc-type 137 Cs source with an activity of 370 kBq. All devices showed an increase in the values of current with the increase in radiation dose up to a certain level. Capacitors could be recommended for high-dose applications, as they showed consistent changes in conductance and capacitance values with an increase in radiation dose up to 6.12 mSv. Resistors doped with 0.2 wt.% of C showed gradual increase in the values of current with the increase in dose up to 4.42 mSv, whereas resistors with 0.5 wt.% of C sustained a lower dose of 1.7 mSv and were damaged on further exposure. pn-Junctions formed with CeO2 films, printed on single side polished P〈1 0 0〉 silicon wafers, exhibited the most sensitivity to γ-radiation. They showed significant increase in the values of leakage current with the increase in dose up to 0.57 mSv and are therefore suitable for low-dose dosimetry applications.

A focused-ion-beam (FIB) machine is a versatile tool used extensively in the integrated circuit (IC) industry for conducting failure analysis, prototype fabrication, and device repair. Lithography can also be performed using FIB for direct patterning of photoresists without using a mask. The FIB technique has several advantages over other maskless processes, such as direct-write e-beam lithography; ion-beam patterning of the photoresist offers higher resist sensitivity and lesser backscattering/proximity effects than the e-beam patterning. In this paper, we investigated a new FIB lithography process, called NERIME (negative resist image by dry etching). The NERIME process is a single-layer resist scheme, which implements a Ga+ FIB exposure of DNQ/novolak-based resists, followed by a near-ultraviolet (NUV) flood exposure, silylation, and oxygen dry etching. The NERIME process could not only yield both positive and negative images, but also achieve a nanometer resolution down to 65 nm and a high aspect ratio for the processed patterns. The principle of the negative image formation was also investigated by TEM and found to be due to the creation of a thin gallium oxide mask layer during etching. The NERIME process could be utilized for specific CMOS processing steps for the next generation technology nodes, such as high-resolution lithography over topographical surfaces.

The overall performance of an electronic nose system will depend on the individual performance of its constituent elements. Although often overlooked, it is clear that careful design/selection of the front‐end signal conditioning circuit is of critical importance if optimal performance of the odour sensing system is to be achieved. In this paper circuits are reviewed, which have been employed as front‐end signal conditioners for resistance‐based sensors in electronic nose systems, with many of the conclusions drawn being equally applicable to other resistor sensors. The relevant equations governing the behaviour of each circuit methodology are derived and advantages and disadvantages are discussed. The performance of the circuit is then quantitatively assessed in a specific test case, in which the maximum sensitivity of the circuit is calculated in relation to the task of interfacing to a theoretical thin‐film conducting‐polymer sensor.

In this work, air core and ferrite core polymer transformers were developed using polymer thick film screen-printing technology. These transformers were printed on 5 × 5cm alumina substrate. The magnetic core material was home-made high permeability Mn–Zn ferrite. An efficiency of 93% and a coupling factor of 0.9 at 500kHz were achieved. This transformer design has five primary turns connected in series and one secondary turn consisting of five turns connected in parallel, the primary and the secondary windings being fully interleaved. All the layers, including the magnetic (Mn–Zn), isolative and conductive layers of the transformers, are made from polymer paste materials. Due to their higher heat radiation, higher power density and lower profile over conventional transformers, these transformers can be used in DC–DC converters for switch mode power supply (SMPS) applications.

Miniaturization of high-efficiency switch-mode power supplies (SMPS) is limited by the size of passive transformers and coils that use large ferrite cores with magnet-wire windings. Fortunately, the availability of planar magnetic transformers and coils (thick and thin films) allows SMPS designers to achieve low-profile architectures that can be easily mounted on a printed circuit board (PCB). The transformer is the key to reduce the size and the cost of the SMPS. Reduction in the size and cost of the transformer can be achieved by changes in both the shape and topology. Improvements in manufacturing technology and reduction in material content can be made by increasing the operating frequency. In this work, polymer thick film transformer was fabricated using thick film screen-printing technology. Polymer base paste is used to print, the magnetic, isolation and conductor layers. The Mn–Zn ferrite material is used as a core material for this transformer. The efficiency for this transformer was measured to be 90% at a frequency of 500 KHz.

This paper investigates the effect of various process parameters on the variation in forward current gain lifetime caused by hot carrier generation of BiCMOS bipolar transistors. Statistical process control and statistical designed experiments were used in this evaluation. The device lifetime in reverse bias operation was calculated from the forward current gain. Various process parameters were examined in this work, i.e., the intrinsic base implant dose and energy, selective collector implant dose, collector plug dose, spacer etch ratio, overetch thickness of nitride spacer and emitter poly etch time. It was deduced that high current gain lifetime can be obtained with high base implant doses, high base implant energies, long bulk nitride etch times and short emitter poly etch times.

The necessity for size decrease in power electronics systems has pushed the operating frequency of these systems into the MHz range. The operation of these systems in the MHz range introduces a number of problems such as excessive coreloss, the skin effect and the proximity effect. In this work, a new high efficiency coreless transformer has been developed using polymer thick film technology, to overcome the coreloss at high frequency. The coils of the transformer are arranged coaxially in two configurations, (1) as a one-layer structure and (2) as two series connected layers in a sandwich structure. The operating principle of this transformer is based on the skin and mutual effect between the coils at high frequency. The copper electroplating process was implemented since an upper limit exists on the thickness of the conductor due to the skin effect under high frequency operation. The well-defined geometry of this thick-film planar transformer renders the parasitic interwinding capacitance and the leakage inductance reproducible. The experimental work performed shows that the polymer thick-film transformer exhibits a low interwinding parasitic capacitance, a high coupling factor of 98% at 9 MHz and shows a maximum efficiency of 98.2% at 10 MHz depending on the load condition.

In this paper a novel strain gauge system on stainless steel and 96% alumina substrates is described incorporating a Wheatstone bridge network, thick-film piezoresistive strain gauges, instrumentation, and a novel thermal and resistor mismatch tolerance correction software. The resistors in the Wheatstone bridge are fabricated with a novel mixture of ruthenium, bismuth and indium oxides and three different thick-film layouts are used. Mechanical measurements are performed using the cantilever beam set-up. The linearity, hysteresis, repeatability, reproducibility, creep, stability and temperature effects are measured for the novel thick-film pastes. The linearity and temperature effect on the output of the different bridge layouts are also examined. The printing of resistors using thick-film technology can result in resistor tolerances of %. Also, thick-film piezoresistors are intrinsically cross sensitive to temperature. These two properties cause an offset voltage to appear at the output of the bridge under no-load/load conditions and a subsequent error in the calculated applied strain. In order to compensate for the offset error voltage, novel correction software has been developed and implemented using a microcontroller. The error in the predicted strain was measured before and after application of the correction software under different bridge layouts and temperature conditions. The error was reduced from a maximum of 45% to approximately 1%. The effectiveness of the correction software in reducing the error suggests that this technique can be used without the need for trimming or bridge balancing.

The electrical properties of fired thick film piezoresistive gauges based on composites of bismuth, indium, cerium and ruthenium oxides are presented. Various material characteristics are analysed, including DC and AC characteristics. The conduction mechanism before and after electroforming is also examined. Structural studies of the fired resistor layers, before and after high field application, are carried out, where evidence of filament growth within the thick film cermet materials is observed. The DC biasing of the MRM device into the negative resistance region shows the ability to produce spontaneous damped oscillations at frequencies up to 3 MHz using a suitable RCL network.

The strain-sensing characteristics of thick-film polymer-based resistors printed and cured on 96% alumina are presented. Two layout configurations have been analysed: planar and sandwich. Various strain-gauge characteristics have been studied, including the mechanical and temperature-dependent properties of the polymeric films. It has been shown that the planar polymer resistors exhibit low sensitivity, comparable to that of metal-foil gauges, whereas the MRM (metal-resistor-metal) configurations exhibit similar characteristics to those of cermet thick-film MRM gauges. It has also been observed that the mechanical properties of the polymeric films are significantly poorer than those of cermet-based gauges. This degradation in performance is attributed to the epoxy/pseudo-plastic structure of the polymeric thick-film resistor layer.

In this paper, Statistical Process Control (SPC) and statistically designed experiments will be used to optimise a recently developed resist schemes i.e., PRIME ( Positive Resist Image by dry Etching ). Orthogonal experiments are designed and conducted in order to produce 0.2 μm lines repeatably in PLASMASK 302U resist. Design rules of 0.1 μm are used due to proximity effects. The data is then explored and analysed using surface plots, boxplots, analysis of variance (ANOVA) and linear regression. It was deduced that e-beam dose and 2nd step etch time were the most significant parameters in the process. Linewidth of 0.2 gm and below were achieved with low values of e-beam dose (250–350μC/cm 2 ) and high values of silylation temperature (205–215°C). The optimum range for NUV flood dose was easily found.

A highly sensitive thick-film sensor developed by using a novel thick-film resistor composition, coupled with design and layout techniques, is reported. The thick film paste is based on the combination of oxides of bismuth, indium and ruthenium. By varying the layout and composition of the thick-film sensors, high gauge-factor values usually attributed to silicon semiconductor strain gauges have been achieved. Various strain gauge parameters have been analysed including linearity, hysteresis and temperature effects. Gauge factor values between 75 to 85 in both resistive and capacitive gauge applications have been observed.

In this paper, simulation of topography effects in photolithography is examined using the two‐dimensional PC based simulator called SLITS (Simulation of Lithography on Topographic Substrates). This program uses FEA software (in‐house written) to solve wave propagation in a photoresist layer and a modified String Algorithm for photoresist development. The simulated results illustrates the effect of topography on the latent and relief images.

Strain sensors printed on ceramic substrates and bonded to steel, are compared with those printed directly on steel. Various strain gauge characteristics are analysed, including linearity, hysteresis, creep and temperature effects. It has been observed that strain sensors printed directly on steel perform much belter than those printed on ceramics (and bonded to steel). The degraded performance of the ceramic sensor is attributed to the adhesive and the inferior mechanical properties of the ceramic itself.

The application of software tools in the development of new processes and novel device structures has become a dominant feature in the microelectronics industry. The use of these tools enables technologists to advance optical lithography to submicron levels of IC fabrication, i.e. 64 Mbit DRAMs. In this work, 2D modelling and simulation of optical microlithography on topographic substrates is investigated. A new program called SLITS (simulation lithography on topographic.substrates) has been developed which calculates 2D latent and relief images. The latent image is calculated by solving the Helmholtz equation using finite element analysis. To generate the relief images, new boundary detection and air/resist movement algorithms, which are not features of any traditional lithographic simulator have been designed and implemented. Relief images produced by SLITS and an earlier program ANKAN for a resist on planar substrate are compared and analysed. We also have investigated notching effects in a ph...

The aim of this paper is to present the methodology and tools used to debug a system comprising a HDL, microprocessor and Rocket I/O in a Partial Reconfiguration flow for sensor reading. The complexities of this system make it impossible to use a simple simulation tool such as Modelsim to assess the top level design functionality. The Bus Macros (BM) that interface between the static region and the reconfigurable region of the top level design make it impossible, as there is no simulation model for them. In general, 30% of the development time is taken by design and 70% by the test of the design functionalities. But many factors tend to increase testing time. The following are some of them: important signals are embedded deep in logic, design parts run at different speeds, so the computer screen cannot show all the data in different clock domains at the same time; the simulation time is too long; the design works in simulation but it does not work in hardware, and so on. This paper will present a practical case and the strategy used to debug it. The following software are used for these tests: ISE (Integrated Software Environment) 9.2 Service Pack 4 with the Partial Reconfiguration layout PR7, XPS (Xilinx Platform Studio) 9.2 Service Pack 2, PlanAhead 10.1.6, Chipscope 9.2 Service Pack 4 and two Virtex-5 boards.

In recent years, there has been numerous research papers reported on the use of DNA biosensors for the detection of foodborne pathogens. However, none of the papers to date reflect the detection of foodborne pathogens directly in food using a handheld DNA biosensor.

The proximity printing process in photolithography can be simulated to compute the diffraction-induced variation in resist profile during exposure. The Fresnel approximation has been used to compute the aerial image profile assuming three apertures in close proximity. The resist is characterized by its contrast curve to generate the 3-dimensional resist image. A test mask was designed and fabricated to verify the simulation results. Experiments were performed to obtain resist images which were studied with a scanning electron microscope. We report an interactive procedure to approximately estimate the values of exposure dose and proximity gap. The match that was obtained between theory and experiment was extremely good.

We combine electron beam lithography (EBL) with conventional microscale metal deposition and etch process technologies, to fabricate bolometer devices with nanoscale feature critical dimensions (CDs). We report the creation of titanium (Ti) bolometer devices with 70 nm minimum feature CDs, and total bolometer film thicknesses ranging between 40 nm and 120 nm. Our new nanobolometer devices integrate with conventional CMOS and MEMS fabrication processing, to create thermally isolated sensors with nanoscale feature sizes on a 0.5 mum CMOS base process. We present temperature coefficient of resistance (TCR) data for our new devices, and report a nanobolometer TCR performance of 0.22%/K at 70 nm CDs, a TCR value comparable to figures reported for Ti-based uncooled microbolometer devices.

The novel system is presented that utilises change in the resonant frequency and impedance as an indicator of the pH level of the solution, brought in contact with a sensor. Mixed metal oxides of Bi2O3 and Nb2O5 formed the basis for thick film capacitive sensors investigated in this research work. AD5933 impedance converter was used to monitor real-time changes in the electrical properties of tested capacitors. The system showed superior sensitivity to the pH level, with instant response being recorded. Heating the sensors restored their initial properties, and they were repeatedly used for pH sensing. It is envisaged that findings of this work would form the basis for compact system employed for real-time pH monitoring.

Misalignment of patterns between different masking layers of integrated circuit is becoming a limiting factor in achieving higher density circuits. A single test structure has been designed and developed to measure the amount of misalignment between various masking levels in CMOS/NMOS technology. Measurement is done electrically. The test structure can be implemented in the mask set of normal VLSI circuits as drop-in to evaluate misalignment of any combination of layers in the whole fabrication sequence.

In this paper, we present a discussion of work done in tracking an embedded object. A special application to telemetry capsules in the gastrointestinal (GI) tract using radio frequency (RF) signals is highlighted. We present the mathematical analysis of the procedure and consequently, an experimental validation of the concept from data captures to position determination using non linear least squares approximation. Finite difference time domain (FDTD) simulation of a suitable dipole antenna employed in the work is also presented to show that within the test range, the radiation pattern of a dipole at about 433 MHz is suitable for detecting an embedded object that is subject to the characteristics of tissue and other related structures.

peer-reviewed A prototype of miniaturized, low power, bi-directional wireless communication system was designed for in vivo pressure monitoring. The capacitive pressure sensors have been developed particularly for the medical field, where packaging size and minimization of the power requirements of the sensors are the major drivers. The pressure sensors have been fabricated using a 2.4 pm thick strain compensated heavily boron doped SiGeB. In order to integrate the sensors with the wireless module, the sensor dice was wire bonded onto TO package using chip on board (COB) technology. The telemetric link and its capabilities to send information have been examined on a test bench. A full pressure range from 0 to ]OkPa was generated using either air or water pressure pumped through connected tubes to simulate the environment similar to the one inside the gastrointestinal (GI) tract.

Figure 1. Response of a 90nm In2O3:ZnO:SnO2 thin-film structure with Cu interdigitated electrodes to gamma radiation.2 Inset: response to a gamma-dose from 0 to 20mGy of thin films with different electrode parameters. used as a disinfectant and deodorizing agent,1 and emitted during the operation of electronic devices such as photocopiers and laser printers. Its deleterious effects on human health include respiratory inflammation and congestion, pulmonary edema, hemorrhage, and even death. Measurements of ozone concentrations are typically carried out with analytical instruments based on photometric, chemiluminescence, and fluorescence techniques, including iodide methods, passive sampling, mass spectrometry, and remote monitoring. These techniques are accurate and sensitive

peer-reviewed The aim of this study is to design and develop a wireless sensor system integrating 24 bits analog to digital converter (ADC) and long range RF transceiver unit. The system is reading from two types of sensors, pressure and temperature. The serial communication between the ADC unit and RF transceiver is controlled by Spartan-3 FPGA device. A number of tasks are implemented by the FPGA device like interfacing, buffering and compression. A capacitive interface circuit has been employed for the pressure sensors and it is based on the principle of capacitance-frequency-voltage conversion. The RF transmitter is communicating with the FGPA through handshaking protocol and sending the data through ISM band. The pressure data will be compressed to avoid sending any repeated values aiming further reduction in the power consumption. EI

peer-reviewed A prototype of miniaturized, low power, bidirectional wireless communication system was designed for in vivo pressure monitoring. The capacitive pressure sensors have been developed particularly for the medical field, where packaging size and minimization of the power requirements of the sensors are the major drivers. The pressure sensors have been fabricated using a 2.4 μm thick strain compensated heavily boron doped SiGeB. In order to integrate the sensors with the wireless module, the sensor dice was wire bonded onto TO package using chip on board (COB) technology. The telemetric link and its capabilities to send information have been examined on a test bench. A full pressure range from 0 to 10kPa was generated using either air or water pressure pumped through connected tubes to simulate the environment similar to the one inside the gastro Intestinal (GI) tract. EI

In aggressive industrial processes, power plants and radioactive waste storage places it is important to monitor the level of radiation. To minimise personnel exposure a wireless system is presented, where thick film MgO and CeO2 capacitors with Ag interdigitated electrodes were used as prototype radiation sensors. MgO and CeO2 thick films were monitored during radiation exposure using a capacitance to digital converter system. A monotonic increase in the values of capacitance from 1.493 pF to 1.537 pF was recorded for MgO as a result of 32.55 mGy J-dose of A 137 Cs J-source. Counterpart CeO2 films were shown to be less susceptible to radiation. Moreover, the response of MgO sensor was monotonic over the whole range.

A novel cost-effective real-time gamma radiation monitoring system based on metal oxide thick films was designed and tested. The changes in capacitances of ZnO and SnO2 thick film capacitors with interdigitated electrodes were monitored in real time under the influence of gamma radiation using miniaturized, low power, bi-directional wireless communication system. The capacitive interface circuitry was based on a Delta-sigma (SigmaDelta) modulator using switched capacitor (SC) circuit architecture with integrated on-chip temperature sensor. At the base station side, an frequency shift keying (FSK) receiver/transmitter is connected to another MCU unit, which send the received data or received instructions from a PC through a graphical user interface GUI. Industrial, scientific and medical (ISM) band RF (433 MHz) was used to achieve half duplex communication between the two sides. All the modules of the mixed signal system are integrated in a printed circuit board (PCB) of size 22.46times20.168 mm. The overall system supply voltage is 2.7 V maximum. 137Cs source with an activity of 370 kBq was used. An increase in the values of capacitance with radiation was recorded for both films to a certain dose level, determined by the material of sensitive layer.

peer-reviewed The study in this paper is focused on the improvement of a Field Programmable Gate Arrays (FPGA) based design using a hierarchical analysis tool offered by XILINX PlanAhead'TM. During this work, PlanAhead software is used to address any problems on the physical side of our FPGA design flow in order to add more visibility and control. The target system is reading analog information recorded by a biomedical sensor in a transmitting unit attached to the patient. The recorded data is converted digitally using analog to digital converter (ADC) and sent to FSK transmitter through FPGA. Verilog HDL has been used to develop and implement the required functions of the FPGA, such as bus interfacing, data buffering, compression and framing. The system performance has been optimized using a recent comprehensive tool in order to reach and maintain the goals of the design. EI

The electrical properties of screen-printed TiO2 based thick films were explored in terms of gamma radiation influence. Screen-printed pn-heterojunctions and resistors were exposed to gamma-radiation from a 137Cs source with an activity of 370 kBq. To form the resistors, a doping of TiO2 paste with 2 wt.% of carbon was implemented to improve their conductivity. All samples showed an increase in the values of current with increasing radiation dose. The diode-type structures sustained a dose of 513 muSv, with considerable increase in leakage current values. Counterpart resistor-type structures experienced a three-order of magnitude increase in the values of current after irradiation with a dose of 7.524 mSv. Furthermore, S-type switching, followed by a forming effect were monitored at this stage, clearly attributed to the influence of gamma radiation

Focused ion beams (FIB) have been widely used as a patterning lithography technique for advanced ICs and optical masks fabrication. FIB lithography has certain advantages over the direct-write electron beam lithography in terms of resist sensitivity, backscattering and proximity effects. However, combining the FIB exposure with both Top Surface Imaging (TSI) and dry etching will further extend its advantages towards anisotropic processing of thicker resist layers in comparison to those used by the conventional lithography processes. The newly developed NERIME (Negative Resist Image by Dry Etching) process combines these advantages by the incorporation of focused Ga+ ion beam (Ga+ FIB) exposure, near UV exposure, silylation and dry etching. The work described here follows our investigations into the NERIME process for nanostructure applications and outlines a simplified (two-step) process incorporating FIB exposure and oxygen dry development. The two-step modified NERIME process is a negative working TSI system for DNQ/novolak based resists. Results show that Ga+ ion beam dose higher than 800μC/cm2 at 30keV can modify the exposed resist areas as to withstand the subsequent oxygen plasma etching, thus giving formation of negative resist image. In this study, nanometer resist patterns as small as 30nm with high aspect ratio of up to 15 were successfully resolved due to the high resolution ion beam exposure and anisotropic dry development. The proposed two-step lithography scheme could be utilized for the fabrication of critical CMOS process steps, such as sub-100nm gate formations and lithography over substantial topography.

Top Surface Imaging (TSI) is a well established technique to improve resolution of optical lithography, deep UV (248 nm) lithography and 193 nm lithography. The Positive Resist Image by Dry Etching (PRIME) process is a high-resolution single layer lithography scheme incorporating electron-beam exposure, near UV exposure (365 nm), silylation and dry development. In this paper, the liquid-phase silylation process step in PRIME with Shipley SPR500A-series resists is experimentally, investigated, and a new efficient process has been developed The impact of different silylating agents is characterised using FT-IR spectroscopy SIM spectrometry and cross-sectional SEM and TEM. Liquid-phase silylated patterns of SPR505 and SPR510 resist are presented, indicating almost vertical silylation sidewall profiles and high-silylation contrast when using Hexamethylcyclotrisiloxane (HMCTS) silylating agents. Results show that in case of e-beam exposure, a dose of 50 C/cm/sup 2/ at 30 keV is efficient to crosslink the resist and prevent silylation.

Focused Ion beam (FIB) lithography has significant advantages over the electron beam counterpart in terms of resist sensitivity, backscattering and proximity effects. However, combining the FIB lithography with Top Surface Imaging (TSI) will extend its advantages by allowing anisotropic processing of thicker resist layers. This paper reports the development of novel single layer lithography process by combining focused Ga + ion beam (Ga + FIB) lithography, silylation and oxygen dry etching. The Negative Resist Image by Dry Etching (NERIME) is a TSI scheme for DNQ/novolak based resists and can result in either positive or negative resist images depending on the extent of the ion beam exposure dose. Results show that Ga + ion beam dose in the range of 1μC/cm 2 to 50μC/cm 2 at 30keV can successfully prevent silylation of the resist, thus resulting in the formation of positive image after the dry etching. A negative image can be formed by using a second Ga + ion beam exposure with a dose higher than 900 μC/cm 2 at 30keV to pattern lines into the original exposed resist area. It was observed that resist regions exposed to such high doses can effectively withstand oxygen dry development, thus giving formation of negative resist image. In this study, nanometer resist patterns with high aspect ratio up to 15 were successfully resolved due to the ion beam exposure and anisotropic dry development. This novel TSI scheme for ion beam lithography could be utilized for the fabrication of critical CMOS process steps, such as deep isolation trench formation and lithography over substantial topography.

This communication presents the design and simulation of a new CMOS bridge to frequency converter with gain and offset control. This circuit incorporates adjustable operating and centre frequencies. When the Wheatstone bridge was balanced, the simulated centre frequency varied from 10.9 kHz to 220 kHz by changing the external capacitor from 1.5 nF to 0.05 nF. Furthermore, for an unbalanced bridge, i.e., the resistors in the bridge were equal to their nominal value plus (or minus) 50ω, the variance from the centre frequency changed from 4.55 kHz to 67 kHz as the external capacitor was decreased. The gain and offset control features were implemented using pulse integrating frequency to voltage conversion and a differential amplifier with voltage inputs for gain and offset control. As the gain control frequency was varied between 60 and 200 kHz, the output centre frequency varied from 114 to 25 kHz. The offset control feature was simulated for the bridge resistors deviated by 50 ω.

The implementation of statistical process control coupled with a failure mode evaluation analysis had failed to produce feature sizes consistently on the target of 5 micrometers . The process was in control but was not capable of delivering product consistently within specification. A Taguchi-type experiment was organized to maximize the process output. Several experiments were conducted varying just one factor at a time. This procedure identified (a) potential nonlinear response factors and (b) appropriate levels for the Taguchi experiment. Six important factors and one potential interaction (exposure and develop time) were identified. The L8 design of Taguchi's arrays was used and each experiment was repeated at both high and low humidities and different ambient temperatures. Significant factors and their appropriate levels were identified and the predicted response was 4.956 micrometers . The confirmatory runs averaged 5.005 microns.

Many designs of misalignment test structures have been developed to evaluate registration error. It is desirable to compare the capabilities of these structures. However, a quantitative measure of comparison for such structures is not available. An attempt has been made in this paper to evaluate a quantitative comparison criterion. Technical merit of a test structure can be determined from the accuracy and precision of the measurement data. A Figure of Merit(FOM) is described here, for comparing the capabilities of two or more such test structures quantitatively.

Focused ion beam (FIB) lithography has significant advantages over the electron beam counterpart in terms of resist sensitivity, backscattering, and proximity effects. However, combining the FIB lithography with top surface imaging (TSI) will extend its advantages by allowing anisotropic processing of thicker resist layers. This article reports the development of novel single layer lithography process by combining focused Ga+ ion beam (Ga+ FIB) lithography, silylation, and oxygen dry etching. The negative resist image by dry etching is a TSI scheme for DNQ/novolak based resists and can result in either positive or negative resist images depending on the extent of the ion beam exposure dose. Results show that the Ga+ ion beam dose in the range of 1–50 μC/cm2 at 30 keV can successfully prevent silylation of the resist, thus resulting in the formation of a positive image after the dry etching. A negative image can be formed by using a second Ga+ ion beam exposure with a dose higher than 900 μC/cm2 at 30 keV ...

In this work, a PVDF thick film paste was deposited onto interdigitated electrodes to form a capacitor. Two different substrates, alumina and Melinex® were used. Capacitors, fabricated on alumina substrates were tested as strain gauges, and showed a high sensitivity with low hysteresis. Capacitors on Melinex® substrates were tested as pressure sensors by adhering them to planar and cylindrical surfaces and subjecting them to pressures up to 300 kPa. Their sensitivity and hysteresis during cycling were examined and compared. It was found that sensors on cylindrical surfaces showed a higher sensitivity, however the hysteresis was also increased. It is thought that this is due to instabilities in the polymer film, accentuated by stretching of the substrate.

The International Technology Roadmap for Semiconductors (ITRS) identifies the shrinking of lithography critical dimensions (CDs) as one of biggest challenges facing the semiconductor industry as it progresses to smaller geometry nodes. Nanolithography, the patterning of masking CDs below 100nm, enables both nanoscale wafer processing and the exploration of novel nanotechnology applications and devices.Focused Ion Beam (FIB) lithography has significant advantages over alternative nanolithography techniques, particularly when comparing resist sensitivity, topography effects, proximity effects and backscattering. FIB lithography uses the implantation of ions, such as Ga+, in its masking process. Ions implanted into resist in this manner typically have shallow penetration depths (When compared with conventional microelectronic lithography, nanolithography techniques such as EUV, electron beam and nanoimprint lithography require expensive process equipment and the use of non-standard process materials.The 2-step negative resist image by dry etching (2-step NERIME) process is a FIB TSI scheme developed for DNQ/novolak based resists, and involves FIB exposure of resist with Ga+, followed by O2 plasma dry development using reactive ion etching. The 2-step NERIME process uses equipment sets and materials commonly found in microelectronic device fabrication (FIB tool, O2 plasma etcher, DNQ/novolak resists), and provides a low-cost and convenient nanolithography option for proof-of-concept nanoscale processing.To be of practical use, a nanolithography scheme must be capable of patterning nanoscale resist features over substrate topography while retaining resist profile control. The nanolithography scheme must also integrate with subsequent plasma etch processing steps that etch various material films such as metals, Si, SiO2, SiN. The 2-step NERIME FIB TSI process has been used to successfully pattern nanoscale (40nm-90nm) resist features on planar and topography substrates. We have also demonstrated sub-100nm etched features on topography substrates using the 2-step NERIME process, reporting 80nm Polycide and TiN etched features, and 90nm Ti etched features, that exhibit excellent profiles and minimal line edge roughness (LER).It is expected that the 2-step NERIME FIB TSI process will be further extended to etch sub-40nm features over topography substrates. The nanoscale etched features will be used to explore proof-of-concept geometry shrink & novel structures, with many possible applications, including NEMs and nanosensors research and development.

This paper reports on the gamma radiation-induced changes in thin oxide films deposited by thermal vacuum technique. Structures of various oxides thin films, such as In2O3, SiO and TeO2 and their mixtures in different proportions were studied. The influence of gamma radiation on In2O3/SiO films has resulted in significant changes in the microstructure of this film. Some kind of agglomerations with variable sizes in the range 0.5-3 µm has occurred. After a dose of 8160 µSv an evidence of partial crystallisation was observed with X-ray diffraction. Structural changes in TeO2 thin film were explored by means of Raman spectroscopy. After they have been exposed to g- radiation, a strong peak appeared at 448.83 cm-1, indicating further transformation to g-TeO2 modification.