A monolithic (Si) massively broadband non-reverberant monopole

Accepted versio

An integrated silicon sensor with microfluidic chip for monitoring potassium and pH

We present ion-sensitive field effect transistor-based sensors, integrated with a microfluidic chip, for monitoring pH and potassium cations. The sensor is strategically located at the base of a well so that the response time of the device depends both on the mean flow through the device and the diffusion coefficient of the analyte being monitored. This would enable monitoring of ions in the presence of larger molecules. The dependence of the device response time on diffusive transport of analytes was examined through a numerical study of the flow field and the passive diffusion of a chemical species. The predicted device response time was compared with the experimental measurements and reasonable agreement found. The general dependence of device response time on geometry, flow rate, and analyte diffusion coefficient was derived. These devices can be used with biological fluids where monitoring of pH and cations provide vital information about the well-being of patients. © 2010 Springer-Verlag

DNA logic-A novel approach to semiconductor based genetics

In the coming years, genetic test results will be increasingly used as indicators that influence medical decision-making. With chronic disease on the rise and the continuing global spread of infectious disease, novel instruments able to detect relevant mutations in a point-of-care setting are being developed to facilitate this increased demand in personalized health care. However, diagnosis for such demand often requires laboratory facilities and skilled personnel, meaning that diagnostic tests are restricted by time and access. This thesis presents a novel configuration for Ion sensitive Field Effect Transistors (ISFETs) to be used as a threshold detector during nucleic acid base pairs match. ISFET-based inverters are used as reaction threshold detectors to convey the chemical reaction level to a logic output once a threshold has been reached. Using this method, novel DNA logic functions are derived for nucleotides allowing local digital computations. The thesis also presents business models that enable such technology to be utilised in point of care applications, and experiment as results and business models given for an HIV point of care example are proposed.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

A low voltage bulk driven downconversion mixer core

ABSTRACT This paper describes a CMOS mixer core, operating at 1GHz, where the RF signal is input via the bulk. The advantages of a bulk driven mixer are low power supply voltages and low power consumption. Simulations have confirmed that a power supply as low as 1V can be used to power the mixer core, which drains approximately 1.6mA. Although the mixer core consumes very low power, it still provides reasonable gain as well as linearity

Cell-bionics: tools for real-time sensor processing

The accurate monitoring of the physiological status of cells, tissues and whole organisms demands a new generation of devices capable of providing accurate data in real time with minimal perturbation of the system being measured. To deliver on the promise of cell-bionics advances over the past decade in miniaturization, analogue signal processing, low-power electronics, materials science and protein engineering need to be brought together. In this paper we summarize recent advances in our research that is moving us in this direction. Two areas in particular are highlighted: the exploitation of the physical properties inherent in semiconductor devices to perform very low power on chip signal processing and the use of gene technology to tailor proteins for sensor applications. In the context of engineered tissues, cell-bionics could offer the ability to monitor the precise physiological state of the construct, both during ‘manufacture’ and post-implantation. Monitoring during manufacture, particularly by embedded devices, would offer quality assurance of the materials components and the fabrication process. Post-implantation monitoring would reveal changes in the underlying physiology as a result of the tissue construct adapting to its new environment

Oxygen plasma induced hydrophilicity of parylene-C thin films

This paper investigates the surface modification of Parylene-C thin films under various oxygen plasma treatment conditions, such as power intensity (50:400 W) and exposure time (1:20 min). The extent of hydrophilicity was investigated through contact angle measurements, and correlations between treatment parameters, film thickness, restoration of hydrophobicity and etching rates were experimentally established. We also demonstrate the selective modification of Parylene-C films, facilitating distinct hydrophilic and hydrophobic areas with µm-resolution that can be exploited in self-alignment applications

A Micropower Vision Processor for Parallel Object Positioning and Sizing

Abstract — A hybrid vision chip is presented for real-time object-based processing for tasks such as positioning and sizing of enclosed objects. This system presents the first artificial silicon retina capable of position and size determination of multiple objects in true parallel fashion. Based on a novel distributed algorithm, this approach uses the input image to enclose a feedback loop to realise a data-driven pulsating action. The fabricated device is shown to achieve a computation-efficiency of at least 725 million instructions per second per milliwatt and capable of processing up to 2000 frames per second. I

A low-cost disposable chemical sensing platform based on discrete components

A method of fabricating low-cost chemical sensing platforms is presented. The device utilizes a discrete metal-oxide-semiconductor field-effect transistor to detect ionic concentrations in electrolytes, with particular emphasis to pH. Measured results indicate a chemical sensitivity of 36.5 mV/pH, while the device exhibits low-leakage currents (in picoamperes) and a drift of 9 mV/h. The proposed technique has a great potential for disposable implementations, while the sensing selectivity of the device can be easily altered, resulting into a versatile platform

Floating gate ISFET chemical inverters for semiconductor based biomedical applications

Ion sensitive field effect transistors (ISFETs) have long been used as analogue chemical sensors particularly for biomedical applications. However, there are some applications where a "yes" / "no" type answer regarding pH change is sufficient. For example, in DNA sequencing the question is whether a chain extension reaction took place or not. Detecting this at the sensing point reduces the sensing process to pH change threshold detection. It eliminates the need for analogue to digital conversion and facilitates an all digital sensory system. This thesis presents Novel Floating Gate ISFET based Chemical Inverters that were created with semiconductor based biomedical applications in mind. It starts by allowing two ISFETs to share the same ion sensing membrane and a common floating gate. Arranging them in a simple FG inverter configuration, their switching may be triggered by either the reference voltage or chemical pH change. In order to enhance its input noise immunity, a chemical Schmitt Trigger is presented. Using ISFETs for the detection of minute pH changes have been a challenge. A simple method to locally scale input referred chemical signal at the ISFET's floating gate is presented. It is based on using the ratio of capacitive coupling to the floating gate. The chemical signal is coupled via the passivation capacitance (Cpass) while an electrical input (V2) is coupled via a poly capacitance (C2). V2 sees the chemical signal with a scaling of Cpass/C2, which can be designed. Finally, ISFETs suffer from initial trapped charges that cause mismatch between devices in the same die. A fast matching method is presented here, that can be used to hugely reduce mismatch of arrays of FG devices. It is based on using indirect bidirectional tunnelling. Two tunnelling structures are added to each ISFET's FG, one adds electrons to it while the other removes them. It is possible to match all ISFETs' initial FG voltages to a point where both tunnelling currents reach equilibrium.EThOS - Electronic Theses Online ServiceGBUnited Kingdo