Harry M. M. Kerkvliet

Ultra-linear, low-cost measurement system for multi-electrode pF-range capacitors

An extremely accurate capacitance-measurement system has beenndeveloped. The system consists of a discrete capacitance-dependentnoscillator and a microcontroller. It is suited to measurenmulti-electrode capacitors, with capacitances up to 2 pF. These can benmeasured with 100 ppm accuracy with respect to a reference capacitor.nThe resolution amounts to 50 aF with a 300 ms total measurement time

A very accurate measurement system for multielectrode capacitive sensors

A very accurate capacitance-measurement system consisting of a discrete capacitance-dependent oscillator and a microcontroller has been developed. It can measure multielectrode capacitors with capacitances up to 2 pF, with an accuracy of 100 ppm with respect to a reference capacitor. The resolution amounts to 50 aF with a total measurement time of 300 ms.

Non-invasive detection of micro-organisms using smart temperature sensors

Abstract This paper describes a new non-destructive way of testing for the presence of micro-organisms in sterilized packaged milk products by measuring their heat production. With a properly designed calorimeter and smart signal processing, the small heat production of the micro-organisms can be reliably detected. A prototype capable of handling 100 cartons of milk, implemented with the novel smart temperature sensors, has been fabricated and tested. These tests show that a relatively small heat production of micro-organisms creating a temperature rise of 5 mK can be detected simply and reliably.

A temperature-controlled smart surface-acoustic-wave gas sensor

Abstract This paper deals with the thermal and temperature-control aspects of a gas sensor based on surface-acoustic-wave (SAW) devices in a dual delay-line configuration. Application of smart temperature sensors combined with a micro-controller in a temperature-control system provides for a high-performance low-cost A/D conversion. An anti-windup control mechanism has been implemented to solve the problem of actuator saturation.

Design and empirical investigation of capacitive human detectors with opened electrodes

In this paper capacitive human detectors using the novel concept of so-called opened electrodes are introduced. These types of detectors have been designed for interactive art application in normal living environments where the electrodes can be integrated, for instance, into the walls, floor and ceiling. Three different examples of these detectors are presented. In all of these detectors the human body acts as a moving electrode that modifies some capacitances in the detector system. The presence and position of a person within the range of 2 m have been detected using perpendicular electrodes. In addition, a tracking area of 2 m × 2 m has been achieved using uniplanar electrodes. The sensitivity of these detectors for the estimation of a persons position has experimentally been investigated and analyzed using simple intuitive circuit models. These models are required in order to develop calibration methods and measurement techniques that reduce the effects of the main parasitic capacitances, and improve the estimation of the persons position.

A Low-Cost Smart Measurement System for Resistive (Bridge) or Capacitive Sensors

A low-cost smart measurement system for resistive (bridge) or capacitive sensors is presented. The measurement system consists of three main parts: the sensor element, a universal transducer interface (UTI) and a microcontroller. The Universal Transducer Interface (UTI) is equipped with front-ends for many types of resistive (bridge) and capacitive sensors. It is a sensor-signal-to-time converter, based on a period-modulated oscillator, which generates a microcontroller-compatible output signal. The microcontroller performs data acquisition of the output signals from the UTI, controls the operating conditions and communicates with a personal computer. Continuous auto-calibration is applied to eliminate the influences of offset and gain errors. According to the experimental results the accuracy and resolution amounts to 13 bits and 16 bits, respectively, for a measurement time of about 100 ms.

High-Resolution Low-Cost Ultrasonic Tracking System for Human-Interface Systems

This work presents a low-speed 3-D position measurement system; designed for tracking simultaneously several target points of the human body. The targets positions are estimated based on acoustic time-difference-of-arrival (TDOA) estimations from different transmitters, which eliminates the effects of changes in the speed of sound. We propose a new signal-processing approach for this system, which is divided in two main parts. In the first part (mobile part on the human body), the signal processing is optimized for low-power consumption, low-sampling frequency, and only 154 samples, reducing the bandwidth required for the signal acquisition. In the second part (fixed part on personal computer), the signal processing estimates the TDOA using different techniques as Hilbert transform, zero-crossing detection, parabolic interpolation, cross-correlation and post-filter analysis. With a minimum number of data yet a high resolution is obtained using the proposed signal processing

A Fast and Accurate Temperature-Control System Using Smart Temperature Sensors.

This paper deals with the thermal and temperature-control aspects of a gas sensor based on Surf ace-Acoustic-Wave (SAW) devices in a dual delay-line configuration. Application of smart temperature sensors combined with a micro-controller in a temperature-control system provides for a high-performance low-cost A/D conversion. An anti-windup control mechanism has been implemented to solve the problem of actuator saturation.