Showing papers on "Gauge factor published in 2005"

Strain-Sensing Characteristics of Carbon Fiber-Reinforced Cement

Abstract: The ability of a structural material to sense its own strain (without attached or embedded sensors) is a positive attribute of smart structures. Specific applications include structural vibration control, traffic monitoring, weighting, room occupancy monitoring, and building security. This article reports on a study of strain sensing in carbon fiber reinforced cement, as enabled by piezoresistivity. This type of strain sensing is characterized by the gauge factor, which is defined as the fractional change in electrical resistance per unit strain. This study involved simultaneous measurement of the piezoresistive behavior in the longitudinal and transverse directions for each specimen. Results showed that, under uniaxial compression, the gauge factor in both longitudinal and transverse directions decrease in magnitude with increasing specimen size from 13 to 51 mm, due to a slight decrease in the degree of preferred orientation of the 5 mm-long fibers. The gauge factor in both directions also decreases in magnitude as the fiber content increases beyond the percolation threshold.

Fabrication of CNT-based MEMS piezoresistive pressure sensors using DEP nanoassembly

Abstract: This paper reports the fabrication technique of a novel carbon nanotubes (CNTs) based MEMS pressure sensor with piezoresistive gauge factor potentially much greater than polysilicon based sensors. By using the dielectrophoretic (DEP) nanoassembly of CNTs and a MEMS-compatible process, we have successfully integrated bundled strands of CNT sensing elements on arrays of polymethylmethacrylate (PMMA) diaphragms. The piezoresistive effects of CNT were preliminarily investigated by measuring the pressure-resistance dependency of the sensors and preliminary results indicated that the CNT-based microsensors were capable of sensing input pressure variations. Moreover, the mechanical properties of the diaphragms were studied experimentally and theoretically, which showed the deflection and strain distribution of the diaphragms with different input pressures, in order to conclusively determine the piezoresistivity of bundled CNTs. Based on these experimental evidences, we propose that carbon nanotubes is a novel material for fabricating micropressure sensors on polymer substrates-which may serve as alternative sensors for silicon based pressure sensors when biocompatibility and low-cost applications arc required.

Investigation of TiO2 thick film capacitors for use as strain gauge sensors

Abstract: 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.

Indium sesquitelluride (In2Te3) thin film strain gauge

Abstract: Thin films of indium sesquitelluride (In 2 Te 3 ) were grown on Mylar substrate using flash evaporation. The strain sensitivity of In 2 Te 3 thin films was studied using cantilever techniques. Hysteresis effect due to strain, compressive-tensile strain and gauge factor is studied at different thickness of In 2 Te 3 thin films.

Technology and integration of poly-crystalline diamond piezoresistive position sensor for cochlear implant probe

Abstract: The possible use of polycrystalline diamond (poly-C) as a piezoresistive position sensor in a cochlear prosthesis is being investigated for the first time. The fabrication process of the poly-C thin film was optimized for compatibility and integration with the Si-based bulk micromachining technology of the cochlear probe. In-situ doped poly-C, films, with a thickness of 1 /spl mu/m, were grown on insulating substrates using MPCVD and patterned by ECR-assisted plasma etching. The piezoresistors can be used as position sensors to detect the curvature and position of the probe during implant surgery. The film quality, electrical properties, contact resistance and piezoresistivity of the poly-C sensors were characterized, which demonstrated a successful integration of diamond technology with the microsystem technology. A gauge factor of 28 was achieved for the poly-C sensors on the probe.

Low firing temperature thick-film piezoresistive composites

Abstract: Thick-film technology has found applications on miniaturised hybrid circuits in various fields (automotive electronics, televisions, ...). This technology is also now widely used for the fabrication of force and pressure sensors that use the piezoresistive properties of thick-film resistors. The goal of this work has been generated by the fact that usual piezoresistive pastes / inks were optimised for applications on alumina, which is the standard substrate for thick-film technology, but ill suited for more flexible substrates such as aluminium, steel or Ti alloys. We were limited by the process conditions of the commercial pastes, in particular the too high firing process that does not allow the use of substrates with melting temperature < 850°C. This technological lack leads to manufacture a new generation of piezoresistive pastes with low firing temperatures (Tf: 500 ... 700°C). In parallel, we aim to optimise the electrical properties (resistance R, temperature coefficient of resistance TCR and gauge factor GF values) by highlighting the link with the structural evolution during the firing process and the obtained properties, and by understanding the conduction process in such percolative systems. Study of usual commercial piezoresistive pastes allowed us to determine that such piezoresistive pastes are composed of a percolating network of nanoconductive RuO2 grains embedded in a lead borosilicate glassy matrix. Evolution during the firing process was emphasised and showed the importance of controlling the firing parameters to assure the best properties for the final thick-film. Commercial pastes are characterised by a TCR value close to 0 ppm/°C, a reasonable sheet resistance value (R 10 kOhms) and a gauge factor comprise between 10-12, that can be influenced by structural and process parameters. Indeed, complementary studies on sensitivity and stability were realised, because of limited available information in literature concerning the effect of firing schedule, particularly of quenching, and have shown that these properties are very dependent on the conditions of firing, although the main commercial pastes showed a moderate stability. In fact, this study showed that a compromise should be found between the different properties (for instance, high GF pastes presents a poor stability), and emphasises the fact that they should be optimised. A manufacturing process has been developed, process never well described in the literature, leading to the realisation of different lead borosilicate glasses. It has resulted in the ability to realise three series of model piezoresistive pastes with different ranges of firing temperatures corresponding to high (700°C), low (600°C) and very low (500°C) firing temperatures. The control of several parameters (glass composition, conductive phase concentration, grain size, firing temperature...) allowed us to direct precisely our research to elucidate the principle of conduction in such percolative systems and the reactions occurring between the elements and their influence on the electrical properties. Structural and electrical properties were studied by varying diverse parameters such as conductive grain size, concentration and firing temperature, and a coherence was found between the electrical behaviour (conduction process) and its relation to the complex nanostructure. In other words, this key chapter presents the results and their interpretation by a model of conduction based on a nonuniversal tunnelling percolation theory and based on a previously unpublished hypothesis. Indeed, it was demonstrated that the piezoresistive response of the pastes changed dramatically depending on whether the composites were universal or not. For the composites with critical exponent t 2, the piezoresistive factor Γ showed no dependence upon the RuO2 volume fraction x, whereas the nonuniversal composites displayed a logarithmic divergence of Γ near the percolation threshold. We have interpreted the piezoresistivity results as being due to a strain dependence of the critical exponent when this was nonuniversal. We have brought forth a microscopic formulation to the phenomenological level proposed by Balberg, and we can now assert that thick-film resistors (TFR) are mainly nonuniversal compounds showing transport exponent t larger than the universal limit t = 2.0. This exponent t depends on strain and leads to a logarithmic divergence of the gauge factor. The possibility of influencing t by external means (e. g. strain) has never been studied so far. We have proposed a new way to investigate percolative systems by studying the behaviour of piezoresistive pastes. After having elucidated the conduction mechanism in such piezoresistive pastes, we studied the influence of different parameters (Tf, grain size, concentration, dwell time) on the main electrical properties (R, TCR and GF). Structural analysis gave a possible interpretation of the results. RuO2 parameters have direct effects on the R, TCR and GF values. Tf acts on microstructure provoking interactions between the bulk components and the substrate (in case of high Tf), and consequently leading to a modification of the electrical properties. The same complementary studies as commercial pastes on stability showed a combined influence of the cooling rate and the temperature dwell-time on R and TCR values. The results are in coherence with commercial pastes. The evolution of the values can be explained by diffusion phenomenon and local microscopic strains due to important cooling rates. The evolution of R upon annealing 250°C was found to depend strongly on the cooling rate for commercial and model pastes, but this observed trend tends to saturate. These new series of low firing temperature were shown to be not as stable as the "best" commercial pastes, but their variations are much similar to "medium" commercial one's. At 250°C, possible evolution mechanisms could involve Ru in glass (dissolved or in clusters), or mechanical relaxation that can be extrinsic (macroscopic thermal mismatch between resistor and substrate) or intrinsic (local thermal mismatch between glass and conductive phase), and which can later relax during annealing. During this analysis, technological problems have been emphasised and a section was dedicated to resolve the problem of the unsuitability of the substrate to the very low firing temperature system, which showed local strain that induced cracks and leading to electrical instability. Moreover, it was shown that these new pastes could be optimised by additives or used on more adapted substrates. However, these obtained series offers a large range of TCR and R values for different low Tf and it would be useful for technological goals. The best proof of the success of our study was the realisation of sensor prototypes based on different substrates such as steel, aluminium and even glass. This work has allowed to realise a detailed study of piezoresistive pastes and to complete previous research in this field concerning the influence of firing parameters (quenching) and annealing studies. From a scientific point of view, this first step allowed to show that nanostructure, conduction mechanism and electrical properties are intimately linked. By choosing adequate and relevant compositions, structure and firing, we proposed a new way to unveil the conduction process that has not been yet elucidated. From a technical point of view, their stability could be enhanced with a higher GF or adapted TCR. However, they present a large range of applications because of their different Tf and their different TCRs. Thanks to this particularity, these pastes could be used on different substrates, and we could expect a larger technological impact by optimising our piezoresistive pastes by additives to better control their properties.

Comparison of recoated fiber Bragg grating sensors under tension on a steel coupon

Abstract: One of the key elements in a structural health monitoring system is the sensing element and data acquisition system. One type of fiber optic sensor used to measure strain is the fiber Bragg grating. Bragg gratings are fabricated using different methods. One method involves placing a mask pattern over the optical fiber and projecting UV light through it to change the refractive index of the core. However, before the grating is written into the core of the fibre, the outer fibre coatings must be stripped away either mechanically or chemically. Fibre Bragg gratings are then recoated after the grating has been written to maintain the strength and flexibility of the fibre by protecting the exposed glass from damage. Acrylate and polyimide are two types of recoat material typically used on fibre Bragg grating sensors. This work is a controlled comparison of polyimide and acrylate recoated fibres for Bragg grating strain sensors. The comparison was carried out using a tension test coupon with recoated FBG and electrical strain gauges bonded to its surface. The tension test specimen was made of cold rolled steel and was designed according to ASTM A30-97a standard. The dimensions were chosen such that three fibre optic sensors and a strain gauge can be attached on each side. The load was applied in 40 μe steps until the strain reached approximately 200 µe. The load was then incrementally decreased back to zero. FBG sensors from 2 manufacturers were compared. For the first manufacturer the Acrylate coated sensors required a gauge factor is 0.75 in order for electrical and FBG strain readings to agree. For Polyimide coated sensors, the appropriate gauge factor was very close to the theoretically predicted value of 0.8. Using these gauge factors, the error between the first manufacturers sensor readings and the strain gauges was well within ±5µe. On the other hand, the second manufacturers sensors did not perform nearly as well. Their readings were substantially lower than the corresponding electrical strain gauges readings and varied from 7% to 13% below expected strain readings. This study demonstrates that bonded FBG sensors can reliably measure strain, but that not all manufacturers are producing recoated FBG sensors to the standard required for strain sensing in civil structures.

Effect of oxygen content on piezoresistivity of indium tin oxide thin films prepared by pulsed laser deposition

Abstract: The piezoresistivity of thin films of indium tin oxide prepared by pulsed laser deposition has been measured as a function of the O-to-(In+Sn) atom ratio. The oxygen-to-metal atom ratio was determined through Rutherford backscattering spectrometry and x-ray photoelectron spectroscopy analyses. Gauge factors, defined as the fractional change of the film resistance to the applied strain, increase with the film’s oxygen content. The deposition under 50 mTorr oxygen pressure resulted in the film with the largest oxygen-to-metal atom ratio, 1.92, and a gauge factor of −14.5. A model based on hopping conduction is proposed. Results from this model are consistent with the sign and magnitude of the observed gauge factors.

Micro force sensor with piezoresistive amorphous carbon strain gauge

Abstract: In this contribution, we report for the first time on a piezoresistive amorphous carbon (a-C) strain gauge successfully integrated into a silicon micro cantilever force sensor. Amorphous carbon was sputter deposited on a silicon membrane and structured by the lift-off technique using photo resist. Cantilevers comprising a-C strain gauges were etched out of this membrane using TMAH and KOH in a bulk silicon micromachining process. Realized prototypes were tested by applying a variable load to the cantilever free end. We found linear characteristics of the strain gauge resistance vs. the applied force in the range of 0 to /spl plusmn/600 /spl mu/N revealing a piezoresistive gauge factor of a-C of nearly 70.

Design of a piezoresistive surface micromachined three-axis force transducer for microassembly

Abstract: One of the challenges facing microrobotic manufacturing is the ability to sense interactions for force-guided assembly of small devices. There is a need for a force transducer with the ability to sense forces in multiple degrees-of-freedom in the mN range with resolution on the order of 10 µN for microassembly applications. This paper presents theoretical studies for developing a surface micromachined piezoresistive force transducer that can measure normal force in the zdirection and moments about the x and y-axes. The devices proposed here are based on a compliant platform design with integrated piezoresistive sensing elements fabricated in a modified SUMMiT process. Various configurations and sensor element layouts are explored to determine the relationship of the applied forces and moments experienced during assembly and the corresponding strain. Structural and finite element analysis is used to determine the elastic response of the device and establish the best locations and orientations of the sensing elements to effectively utilize the piezoresistive effect of the polysilicon sensors. Initial experiments show the polysilicon piezoresistors to have a gauge factor of approximately 25. The expected sensitivities for these devices are presented.

Polysilicon piezoresistive cantilevers for intermolecular force detection

Abstract: We describe the development of polycrystalline silicon piezoresistive micro/nanocantilevers for the measurement of intermolecular forces in biochemical sensing. The cantilevers have been fabricated both in a dedicated technology and in a commercial CMOS technology with an additional micromachining postprocessing. The sensitivity and resolution required by the application are achieved with cantilevers with submicrometer thickness and width in the micrometer range. The cantilevers have been successfully tested by applying a known displacement with an AFM, obtaining a value of 12 for the gauge factor.

Carbon nanotubes dispersions in polymer matrix for strain sensing applications

Abstract: We have performed studies on the correlation between mechanical deformations and electrical conductance on a new interesting hybrid material, a Single Wall Carbon Nanotubes (SWCNTs)/Poly(3,4-ethylenedioxythiophene) (PEDOT) composite. Two are the synthesis techniques utilized to prepare the composite material in form of few hundreds of nm thick films: a spin coating deposition starting from an aqueous dispersion of SWCNTs and PEDOT, and an electrochemical de*position starting from a dispersion of SWCNTs and EDOT monomer. The composite conductance changes induced by a modulated periodic elongation via a coherent technique have been monitored by measuring the voltage variations of a Wheatstone bridge connected with the films. The measurements were performed on SWCNTs/PEDOT composites layered on a rigid substrate. The piezoresistivity gauge factor (GF) of the various samples was evaluated by comparing their responses to mechanical deformations to those of a commercial strain gauge, sticked on a substrate of the same kind. We found no significant piezoresistive effect in the hybrid material films deposited by means of spin coating while the effect is remarkable for the composites prepared by means of the electrochemical technique. In this case the gauge factor is found to be up to 3-4 times higher than that of the commercial strain gauge.

Fabrication and characteristics of micromachined Ta-N ceramic thin-film pressure sensors

Abstract: This paper describes the fabrication process and characteristics of ceramic thin-film pressure sensors based on Ta-N strain gauges for harsh environment applications The Ta-N thin-film strain gauges are sputter-deposited on a thermally oxidized micromachined Si diaphragm with buried cavities for overpressure tolerance The proposed device takes advantage of the good mechanical properties of single-crystalline Si as a diaphragm fabricated by SDB and electrochemical etch-stop technology, and in order to extend the temperature range, it has relatively higher resistance, stability and gauge factor of Ta-N thin-films more than other gauges The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low nonlinearity and excellent temperature stability The sensitivity is 121-1097 mV/V/spl middot/kgf/cm/sup 2/ in temperature ranges of 25-200/spl deg/C and a maximum non-linearity is 043 %FS

Characterization of Interdigital Capacitive Strain Gauges by Direct Write Technology

Abstract: Interdigitated capacitive strain gauges have several distinct advantages over resistive-based strain gauges, particularly for applications in harsh environments, such as high-temperature environments. In this work capacitive strain gauges have been fabricated using thermal spray technology. Gauges are fabricated using both a direct-write approach where the gauge is fabricated using a computer-controlled deposition system and by ultrafast laser micromachining in which blanket coatings sprayed onto a substrate are subsequently laser micrornachined. Silver coatings were sprayed onto plastic, polymer, composites, fiberglass and alumina to form the strain gauges. An ultrafast laser machining technique was used to fabricate capacitive strain gauges on copper coated printed circuit boards as well as NiCr coatings on alumina substrate. The typical capacitance of strain gauge was in the range of 5∼25 pF. Mechanical tests included gauge factor, linearity and zero shift. Temperature-based measurements include the temperature coefficient of capacitance (TCC) measurements and thermal cycling tests. The devices show promise for use in wireless strain monitoring applications.Copyright © 2005 by ASME

Strain Transduction in Conductor-Modified Polymers

Abstract: We present the fabrication and electromechanical characterization of a class of polymeric high-elongation strain sensors. Samples of polydimethylsiloxane were coated with Creative Materials, Inc.’s 123-27 Electrically Conductive Silicone Ink and the resistance behavior was evaluated in uniaxial tensile tests. Large strains (up to 100%) were observed with monotonically increasing resistance changes. A clear, linear trend up to 65% strain dominated the resistance vs. strain behavior then resistance increased non-linearly. Image processing of the film coupled with a finite element conduction simulation indicate the change in resistance is primarily a geometric effect. Both the conduction path and the polydimethylsiloxane substrate break completely around 100% strain. The samples exhibit a gauge factor of approximately 10.

Study on Piezoresistive of Doped Carbon Nanotube Films

Abstract: The piezoresistive effect in iodine-doped carbon nanotube films was investigated by a three-point bending test. Carbon nanotubes were synthesized by hot filament chemical vapor deposition. The experimental results showed that the gauge factor for I-doped and undoped carbon nanotube films under 500 microstrain was about 350 and 65 respectively at room temperature, exceeding that of polycrystalline silicon (30) at 35°C. The origin of the piezoresistivity in the films may be ascribed to a strain-induced change in the band gap for the doped tubes and the intertube contact resistance and defects for the undoped tubes.

A Novel Method for Determining Pressure Sensitivity of Underwater Shear-Stress Sensor Skins

Abstract: This paper reports the development of a novel method for determining the pressure sensitivity of two types of surface micromachined underwater shear stress sensor skins for micro shear stress sensing applications. The two types of sensors consisted of a thin-diaphragm sensor and a thick-diaphragm sensor. The focus is on the use of a combination of metrology and numerical simulation to theoretically determine the pressure sensitivity of the sensors and compare to experimental data. Using this combination, the nitride diaphragm deflection, the intrinsic stress of the diaphragm, and the piezoresistive gauge factor of the polysilicon sensing element were successfully determined. For the thin-diaphragm sensor, the tensile intrinsic stress and gauge factor were determined to be 28 MPa and 4, respectively. For the thick diaphragm sensor, the average tensile intrinsic stress and gauge factor were 48 MPa and 12, respectively. Using these numbers, the pressure sensitivity of the shear stress sensors was successfully modeled and verified against experimental results.Copyright © 2005 by ASME

Forming method of strain sensor element, and polycrystalline diamond strain gauge

Abstract: PROBLEM TO BE SOLVED: To make gauge factor enhanced by localizing boron doping, near a film surface of a polycrystalline diamond strain gauge, whose film formation is performed by a vapor phase deposition method (hot-filament CVD or microwave plasma CVD method). SOLUTION: By controlling boron concentration or doping depth in the direction of the film thickness from the film surface of the polycrystalline diamond strain gauge X (strain sensor element Y), a boron-doped diamond layer 20(X) is partially formed, and the boron doping is localized near the film surface. For this purpose, a material gas is led in and an undoped diamond layer 10(X) is primarily formed on an insulator 30 in a hot-filament CVD system. After a predetermined time has elapsed, a boron-doped diamond layer 20(X) is secondarily formed by additionally leading gas containing boron in, and the layer thickness is controlled to a half or smaller of the average crystal grain diameter. COPYRIGHT: (C)2005,JPO&NCIPI

Fabrication and Characteristics of Micromachined

Abstract: This paper describes the fabrication process and characteristics of ceramic thin-film pressure sensors based on Ta-N strain gauges for harsh environment applications. The Ta-N thin-film strain gauges are sputter-deposited on a thermally oxidized micromachined Si diaphragm with buried cavities for overpressure tolerance. The proposed device takes advantage of the good mechanical properties of single-crystalline Si as a diaphragm fabricated by SDB and electrochemical etch-stop technology, and in order to extend the temperature range, it has relativery higher resistance, stability and gauge factor of Ta-N thin-fiIms more than other gauges. The fabricated pressure sensor presents a low temperature coefficient of resistance, bigh-sensitivity, low nonlinearity and ereellent temperature stability. The sensitivity is 1.21-1.097 mVN*kgffcmz in temperature ranges of 25-200°C and a maximum non-linearity is 0.43 %FS.

Conductive mechanism and its mathematical model of thick-film strain resistors

Abstract: Some thick-film resistors base on Bi/sub 2/Ru/sub 2/O/sub 7/ were evaluated. The resistors are made by screen-printing thick film paste on Al/sub 2/O/sub 3/ substrates. After printing and drying, the thick-film pastes are fired in a belt furnace. We discuss the conduction mechanism and a strain sensitive mathematical model of thick-film resistors through calculating and taking the measurements of the gauge factor (GF). We also interpreted the phenomenon through the strain sensitive model, and explained the strain sensitive phenomenon, such as the GF mounts up with the barrier height's augmention.

Characteristics of chromium oxide thin-films for high temperature piezoresistive sensors

Abstract: This paper present characteristics of chromium oxide thin-film as piezoresistive sensors, which were deposited on Si substrates by DC reactive magnetron sputtering in an argon-Oxide atmosphere for high temperature applications. The chemical composition, physical and electrical properties and thermal stability ranges of the sensing elements have studied. thin films with a linear gauge factor(GF15), high electrical resistivity (

Hysteresis and drift in a carbon-polymer composite strain sensor

Abstract: A conductive polymer strain gauge was screen printed to produce an active area of 3mm × 4mm The graphite and titanium dioxide loaded thermoplastic device was found to have a resistance of 43kΩ and a gauge factor of up to 20 The higher resistivity and gauge factor result in a lower power consumption and higher sensitivity when directly compared to metal foil strain gauges However, a substantial hysteresis of approximately 80μe was identified in a complete strain cycle from 0me to 730μe The source of this hysteresis was considered to be the thermoplastic matrix Subsequently the viscoelastic nature of the polymer matrix was analysed using the gauge's resistive signal as it changed under applied strains, and this output was then compared to the standard linear solid (or Zener) model from linear viscoelastic theory This model was applied to the data and with some limitations was found to make an improvement to the reported hysteresis

Optimizing piezo-resistive strain gauge characteristics for intelligent strain sensing applications

Abstract: This paper reviews current piezo-resistive characteristics pertaining to conventional and novel piezo-resistive strain transducers. These characteristics govern the performance of the sensor node. In this application, low power consumption, high signal to noise ratio (SNR), sensitivity and resolution in the sensor node are optimized for a distributed sensor network. In this low frequency application at < 100 Hz, it is found that electrical noise can limit the nominal resistance of the strain gauge to be used. By reducing the nominal resistance to lower the SNR, power consumption is increased. Optimization of the nominal resistance for excess noise and other material parameters must take place. Typical values have been used to explore the SNR over a range of resistance values and against frequency. The trade-off is also optimized in the volume and sheet resistance of the piezo-resistive material. Irreversible phenomena such as ageing and material creep are responsible for very low frequency drift (approaching DC) with respect to time and temperature. It is found that this drift is material specific and can be numerically compensated in situ. Maximizing sensitivity of the transducer is desirable to reduce the overhead at the sensor front-end. This overhead is shown to be dependant on gauge factor and the configuration of the strain-sensing circuit. The configuration of the strain-sensing circuit impacts on cost, complexity and SNR.