A critical evaluation of direct electrical protein detection methods

During the last decennia many protein-related electrical phenomena have been studied and applied in a variety of measuring systems, from simple metal electrodes with adsorbed proteins to sophisticated systems with lipid bilayers. Many of the investigations concern the monitoring of immuno reactions. The basis underlying electrical effects of the observed phenomena are the protein modulated dielectric constant, conductivity, electrical potential, ion permeability and ion mobility. In this paper special attention is paid to the capacitive measurements with EIS systems as well as impedance and potential measurements with FET devices. The Donnan theory is treated and applied to the static ImmunoFET operation, explaining the relatively small effects which have been reported. Finally, an alternative approach is described in which the ImmunoFET is applied in a dynamic way, to circumvent the drawbacks of the static measurements

Exploiting the dynamic properties of FET-based chemical sensors

After a long period of mainly static application of ISFETS, other more sophisticated applications are being developed, based on the exploitation of the dynamic properties of ISFETS. Examples are the use of flow-through cells with sample injection and the integration of a pH actuator electrode for very fast titration in a microvolume. The development of an immunoFET makes use of induced transient phenomen

The merit of using silicon for the development of hearing aid microphones and intraocular pressure sensors

An important design rule for a hearing aid is the requirement of a large signal to noise ratio, which is mainly determined by that of the microphone and its preamplifier. It will be shown that in order to increase the signal to noise ratio it is favourable to integrate the preamplifier with the microphone, which implies that the microphone should be made of silicon, preferably with a single wafer technology. For the development of a tonometer for the measurement of intraocular pressure, the application of a silicon force sensor rationalizes that also the flattening of the eye globe is measured with a silicon applanation sensor, instead of by optical means which is the present practice. A sensor construction has been developed, which combines a force, pressure and applanation sensor, all made in silicon

The future of biosensors

Since the development of the glucose sensor by Clark and Lyons in 1962, generally recognized as the first biosensor, many types of sensors have been developed in which a physical or chemical transducer is provided with a layer containing a biological sensing element. The resulting device is called a biosensor, aimed to produce an electronic signal as a function of the concentration of a chemical or biochemical constituent of a liquid, not necessarily of biological origin. Among the many proposed concepts, the integration of biologically active materials with a silicon chip is one of the most intriguing approaches, because it seems the most comprehensive integration between biology and electronics. In this paper the resulting biochips, mainly based on the field-effect principle as the coupling mechanism between the two domains, will be described and discussed with an outlook on the future

The impact of MOSFET-based sensors

The basic structure as well as the physical existence of the MOS field-effect transistor is without doubt of great importance for the development of a whole series of sensors for the measurement of physical and chemical environmental parameters.\ud \ud The equation for the MOSFET drain current already shows a number of parameters that can be directly influences by an external quantity, but small technological variations of the original MOSFET configuration also give rise to a large number of sensing properties. All devices have in common that a surface charge is measured in a silicon chip, depending on an electric field in the adjacent insulator.\ud \ud FET-based sensors such as the GASFET, OGFET, ADFET, SAFET, CFT, PRESSFET, ISFET, CHEMFET, REFET, ENFET, IMFET, BIOFET, etc. developed up to the present or those to be developed in the near future will be discussed in relation to the considerations mentioned above

Design considerations for an isfet multiplexer and amplifier

Design considerations for the multiplexing of pH-sensitive ISFETs are studied and discussed. Experimental results with an ordinary multiplex circuit show transients of the order of several seconds if the output voltage of the applied amplifier is required within an accuracy of 0.5 mV (corresponding to 0.01 pH unit). These transients appear to result from thermal instability of the ISFETs during switching operations, and can be cancelled by guaranteeing a constant chip dissipation. This necessitates the design of a special multiplexer circuit for multiplexing separate ISFETs. The output voltage of the applied amplifier then appears to be stable within 1 millisecond with the required accuracy

Sensors for biomedical applications

This paper considers the impact during the last decade of modern IC technology, microelectronics, thin- and thick-film technology, fibre optic technology, etc. on the development of sensors for biomedical applications

Battery management systems : design by modelling

This thesis describes the subject of Battery Management Systems (BMS), in particular the design of BMS with the aid of simulation models