A novel single-use SU-8 microvalve for pressure-driven microfluidic applications

A novel microfluidic single-use valve for fluid injection and extraction in pressure-driven applications is presented in this paper. The device consists of a thin SU-8 membrane crossed by a resistor that withstands a mechanical stress induced by a pressure difference. When the resistor heats up the membrane, the SU-8 fracture strength drastically decreases causing the valve activation. This device has been designed, fabricated using inexpensive SU-8 and printed circuit board technologies and finally characterized. The hybrid thermal–mechanical microvalve operation principle has been demonstrated and experimental results have shown the device characteristics and performance. Specifically, this design was functional at pressures of 0.8 MPa and opened in less than 3.2 s with an applied power of 280 mW. The simple fabrication process and the absence of moving mechanical parts have made the valve suitable for large-scale integration in lab-on-chip microfluidic platforms

Controladores digitales estocásticos

En este artículo se presenta la realización de controladores clásicos basados en el procesamiento lógico estocástico. Se aporta una descripción de las operaciones aritméticas básicas -suma, resta, multiplicación e integración. EI objetivo de esta arquitectura es proporcionar un conjunto de circuitos simples que permitan realizar estas operaciones con circuitos digitales simples. Como resultado de ello se pueden sintetizar controladores empleando dispositivos lógicos programables (FPGA). EI circuito desarrollado es aplicado a un sistema real con el uso de un convertidor analógico estocástico (ASC)

A Neural Controller for quasi-resonant converters

A neural controller implementing an energy feedback control law is proposed to improve the stability and dynamic characteristics of the series resonant converter (SRC). The cnert)' feedback control is introduced and analysed in discrete time domain. A novel formulation of the control law is suggested. The adaptive control law is learnt by an analog neural network (ANN). An easy imple· mentation of this controller is proposed and applied to a SRC circuit. Simulation results show a good improvement in the SRC response and confirm the validity of the controller

Stochastic pulse coded arithmetic

Among the different pulse codification techniques, stochastic pulse codification has its own arithmetic based on the similarity between Boolean algebra and statistical algebra. Summation and multiplication are the two basic arithmetic operations treated in depth in the literature. In this paper we present two digital stochastic circuits that extend traditional stochastic algebra: a division circuit and a square-root circuit, and the interfaces between the analog and stochastic domain. As a result, we are able to process analog input signals with a simple and complete processing system. These circuits can be implemented in low-cost and low-power digital programmable devices

Characterisation of the fabrication process of freestanding SU-8 microstructures integrated in printing circuit board in microelectromechanical systems

The characterisation of the fabrication process to develop freestanding SU-8 structures integrated in printing circuit board in microelectromechanical systems (PCBMEMS) technology is presented. SU-8 microcantilevers, microbridges, microchannels and micromembranes have been fabricated following the described procedure. Adherence between FR4 substrate and SU-8 has been examined using the destructive blister method, evaluating the surface energy. Residual thermal stress has also been analysed for this integration and compared when using other substrates. Moreover, an estimation of the copper wet etching with cupric chloride has been performed in order to understand how this isotropic etching affects the geometry of the copper structures. Finally, stiction has been observed and examined, estimating the adhesion energy responsible for this effect

Semi-Automatic Lab-on-PCB System for Agarose Gel Preparation and Electrophoresis for Biomedical Applications

In this paper, a prototype of a semi-automatic lab-on-PCB for agarose gel preparation and electrophoresis is developed. The dimensions of the device are 38x34 mm2 and it includes a conductivity sensor for detecting the TAE buffer (Tris-acetate-EDTA buffer), a microheater for increasing the solubility of the agarose, a negative temperature coefficient (NTC) thermistor for controlling the temperature, a light dependent resistor (LDR) sensor for measuring the transparency of the mixture, and two electrodes for performing the electrophoresis. The agarose preparation functions are governed by a microcontroller. The device requires a PMMA structure to define the wells of the agarose gel, and to release the electrodes from the agarose. The maximum voltage and current that the system requires are 40 V to perform the electrophoresis, and 1 A for activating the microheater. The chosen temperature for mixing is 80ºC, with a mixing time of 10 min. In addition, the curing time is about 30 min. This device is intended to be integrated as a part of a larger lab-on-PCB system for DNA amplification and detection. However, it can be used to migrate DNA amplified in conventional thermocyclers. Moreover, the device can be modified for preparing larger agarose gels and performing electrophoresis.Consejería de Economía y Conocimiento de Andalucía P18-RT-1745Unión Europea US-126598

12-Lead ECG modulator and demodulator equipment for telephony transmission

This paper describes a teleassistency system that consists of a modulator equipment for the acquisition. storage and FM transmission of the typical 12 lead ECG signals and a demodulalOf equipment for recovering the original sig- nals in a medical cemer. Switched telephone network and GSM network can be used to transmir the audio fre- quency modulated signal carrying ECG Information

Welding data adquisition based on FPGA

This paper presents the use of FPGA in data acquisition and digital preprocessing of the electric current signal of resistance welding stations. This work demonstrates that electric current has enough information to classify this kind of welds in mass production industries. Parameters extracted with the FPGA excite a classifier that accept o reject the welding junction. This system has been developed using a neural classifier and installed in a welding station of General Motors in Cádiz (Spain). Results confirm the validity of this novel approach

Design of a mobile telecardiology system using GPRS/GSM technology

This paper presents the design and development of a portable electrocardiograph to allow the on-line remote monitoring and real-time cardiac diseases diagnostics of patients from the specialist. This prototype has been satisfactory implemented finding a good balance between optimal signal processing and power consumption using a GPRS/GSM modem and a SMT low voltage microprocessor board