Ultra-low power precision ISFET readout using global current feedback

A solid-state chemical sensor ion sensitive field effect transistor (ISFET) that operates in weak inversion and interfaces with negative current feedback to maximise linearity is proposed. The power consumption of this circuit when operating in the weak inversion region is in the nanowatt range, which makes it suitable for biomedical applications     

Drift reduction in ion-sensitive FETs using correlated double sampling

A discrete-time technique, correlated double sampling (CDS), as a method to reduce drift during ion-sensitive field effect transistor (ISFET) operation is presented. The CDS technique exploits switched capacitors to resolve low-frequency signal errors such as drift and 1/f noise, which are generated by an ISFET and its readout. In conjunction with post-processing, experimental results confirm drift reduction using this technique.     

Influence of reinforcement and processing on steel-based composites: Microstructure and mechanical response

Steel matrix composite reinforced with 2–4 vol.% titanium diboride particles was fabricated successfully by powder metallurgy route through hot pressing method. Influence of sintering parameters on densification was investigated by measurement of density of resultant composites. Microstructural analysis of hot-pressed materials was performed. Hardness and deformation behavior under constant load were evaluated by conducting microhardness and nanoindentation tests. The addition of titanium diboride proved to be effective for enhancement of hardness and strength. Composite with 4 vol.% titanium diboride sintered at 1100°C resulted in improved hardness and elastic modulus which could be related to Orowan strengthening resulting from homogeneous distribution of fine titanium diboride particles in steel matrix. The results indicate that proposed method is economically feasible to process steel matrix composites with improved properties. A comparatively lower temperature and pressure offers better control of interface kinetics and microstructure.     

64 pH-ISFET averaging array employing global negative current feedback

The previously reported discrete ISFET using current feedback has been redesigned in a CMOS platform with an array of ISFETs to improve the performance of the single ISFET's readout. The circuit novelty is the averaging of ISFET currents generated by a cluster of 64 ISFETs with a global current feedback. Simulation results from the 0.18 μm CMOS process also indicate improvements of high signal-to-noise ratio with power consumption to early μW. As a result, it all leads to benefit biomedical applications.     

Improving prediction of exchange rates using Differential EMD

Volatility is a key parameter when measuring the size of errors made in modelling returns and other financial variables such as exchanged rates. The autoregressive moving-average (ARMA) model is a linear process in time series; whilst in the nonlinear system, the generalised autoregressive conditional heteroskedasticity (GARCH) and Markov switching GARCH (MS-GARCH) have been widely applied. In statistical learning theory, support vector regression (SVR) plays an important role in predicting nonlinear and nonstationary time series variables. In this paper, we propose a new algorithm, differential Empirical Mode Decomposition (EMD) for improving prediction of exchange rates under support vector regression (SVR). The new algorithm of Differential EMD has the capability of smoothing and reducing the noise, whereas the SVR model with the filtered dataset improves predicting the exchange rates. Simulations results consisting of the Differential EMD and SVR model show that our model outperforms simulations by a state-of-the-art MS-GARCH and Markov switching regression (MSR) models.     

A novel, low power biosensor for real time monitoring of creatinine and urea in peritoneal dialysis

Novel biosensors, based on immobilized creatininase, creatinase and urease are developed, using ISFETs with weak inversion at pH 6–8 and 37.0 °C. The ISFETs with circuitry, demonstrate a linear relationship of urea and creatinine at the range of 0–200 and 0–20 mM, respectively. Preliminary results show that biosensors operating in weak inversion mode can eliminate many of the disadvantages of ISFETs operating in the strong inversion region, providing a wide dynamic range output in nanoAmp. Such characteristics fit the analytical requirements for improving real-time monitoring in peritoneal dialysis (PD). Further work covers stability of ISFET sensors biased with CMOS circuits in the weak inversion mode working in the room temperature of 15–40 °C.