Carmen Aracil

Reconfigurable distributed network control system for industrial plant automation

Use of advanced communication technologies, highly integrated control, and programming platforms drastically increases the performance of industrial control systems. That is the case of Motronic, where the synergistic collaboration between industry and academia has led to an advanced distributed network control system. To be commercially successful, it needs to have a low cost and to be robust, even if this requirement implies that it is a custom design and not based on previously existing commercial solutions. Use of standards and off-the-shelf products lower development costs, but usually raise production costs. In this paper, we show that, in certain applications, design of a new system from scratch is more advantageous. This system comprises a set of dynamically reconfigurable local controller nodes, a graphical programming environment, a remote supervision and control system, and a fault-tolerant fiber optical network. TCP/IP connectivity is provided by the use of a local gateway. Motronic is currently being applied in the integrated control of large production plants and in energy and power management industries.

BETTS: bonding, exposing and transferring technique in SU-8 for microsystems fabrication

A novel fabrication process called BETTS (bonding, UV exposing and transferring technique in SU-8) is presented in this paper. SU-8 layers can be transferred and patterned over SU-8 microstructures by means of a removable, flexible and transparent substrate. This substrate is composed of a thin acetate film, which can be also used as a mask, and a cured PDMS layer deposited over it. SU-8 is then spin coated and transferred to the SU-8 structures performing simultaneously the steps of bonding and transferring by UV exposure. Due to the low adhesion between PDMS and SU-8, acetate film removal can be easily performed. BETTS provides easy, irreversible and robust SU-8 to SU-8 bonding, where the absence of oxygen plasma equipment or vacuum systems decreases drastically the fabrication cost and time involved. The reported fabrication process makes it possible to fabricate complex SU-8 three-dimensional structures using a simple and inexpensive procedure and also ensures its compatibility and integration with microfluidic and PCB-MEMS devices. Some specific applications such as multilevel microchannel network, patterned membranes, microchambers and microvalves are reported to demonstrate the potential of the proposed process.

Tracking Control System Using an Incident Radiation Angle Microsensor

For some industrial applications, an accurate estimation of a light source position is needed. That is the case for a heliostat, a device that projects sunlight onto a focus hundreds of meters away from its aiming point. In this paper, we present a novel sensor design for generating an alignment error signal. Included is a detailed study of its response, which shows that certain geometrical design parameters are necessary to achieve desired accuracy. This sensor has been implemented using microelectromechanical system techniques to achieve a robust structure at low cost and it has been successfully applied to sun-tracking systems. Experimental results obtained in field tests are included

Tracking system for solar power plants

In this paper a sun tracking system is presented. The main component of this system is a solar sensor. It is a light source position sensor. The sensor is made using MEMS technology to increase the sensitivity of the sensor and reduce manufacture cost. An algorithm is also designed to implement the control system considering all the different meteorological conditions. Two scale models has been made to test the complete system, that is, as much as the sensor as the algorithm. The scale models are based in real applications where the sensor can be incorporated, as they are heliostats and photovoltaic cells. The experimental results are successful and show the robustness and high precision of the system

High-integrated microvalve for Lab-on-chip biomedical applications

This paper presents a single-use fluid microvalve for lab-on-chip (LOC) applications that combines printed circuit board and SU-8 technologies. The main advantage of this device lies in the simplicity and low cost of the fabrication process. The operation of the valve consists in extracting a certain quantity of fluid by mechanical phenomenon when a membrane is melt by a resistor. The design is conceived to be integrated in an array composed by microneedles modules and biosensing devices. Integration of the microvalve has been maximized with the planar layout presented here. With this merge of technologies is possible to include microfluidics and electronics in the same LOC device, which is intended to biomedical applications. Experimental results that show the microvalve performance are presented.

Low consumption single-use microvalve for microfluidic PCB-based platforms

In this paper, a single-use and unidirectional microvalve with low consumption of energy for PCB-based microfluidic platforms is reported. Its activation is easy because it works as a fuse. The fabrication process of the device is based on PCB technology and a typical SU-8 process, using the PCB as a substrate and SU-8 for the microfluidic channels and chambers. The microvalve is intended to be used to impulse small volumes of fluids and it has been designed to be highly integrable in PCB-based microfluidic platforms. The proposed device has been fabricated, integrated and tested in a general purpose microfluidic circuit, resulting in a low activation time, of about 100 μs, and a low consumption of energy, with a maximum of 27 mJ. These results show a significant improvement because the energy consumption is about 84% lower and the time response is about four orders of magnitude shorter if compared with similar microvalves for impulsion of fluids on PCB-based platforms.

Highly Integrable Pressurized Microvalve for Portable SU-8 Microfluidic Platforms

In this paper, a highly integrable pressurized thermo-pneumatic microvalve for impulsion and handling of fluids in portable SU-8 microfluidic platforms is reported. The microvalve aims to overcome the dependence on external pressure sources for actuation in this kind of platforms by incorporating a pressurized chamber in the design. The microvalve consists of two modules. The first one is a pressurized SU-8 chamber which makes the microvalve portable and is used to store pneumatic energy, and the second one is a gold wire inserted in a thin SU-8 wall to make a thermo-pneumatic and single-use actuation. The gold wire heats the thin wall up, and the pneumatic energy stored in the chamber exerts pressure on the wall simultaneously. The wall breaks due to the combination of these effects, releasing the pressure stored in the chamber, and creating an unidirectional flow in an output channel. The microvalve has been fabricated and tested in the laboratory showing an activation time of 1 s and a required energy of 188 mJ, values which fit the theoretical model. The advantages of this microvalve as a microfluidic component lie in its independence of external pressure sources, its high integrability with electronics and microfluidics in the same substrate [printed circuit board(PCB)], and the low consumption with respect to other PCB/SU-8 microvalves.

Safety valve in PCB-MEMS technology for limiting pressure in microfluidic applications

A safety valve that prevents liquid from flowing through a fluidic circuit when its pressure is larger than a certain threshold is presented in this paper. The valve has been designed to be integrable in PCB fluidic systems, and its parameters can be modified easily to adapt the threshold pressure. Fabrication process uses PCB as the substrate, and the copper present as a sacrificial layer. Structural part is made of negative photoresist SU-8, which is deposited on top of copper and is released to form a suspended beam when copper is etched away. The experimental characterization of the valve is presented, showing its correct operation.

Low Cost Fluid Microextractor for Lab-on-Chip

A simple and low-cost fluid microextractor for lab-on-chip (LOC) applications is presented in this paper. This device combines Printed Circuit Board (PCB) and SU-8 technologies, achieving a simple fabrication process. The main advantages of this microextractor lie on its activation process, great functionality and ease of integration due to its planar structure. The operation is a merge of thermal and mechanical phenomena, where a membrane is melt by a resistor, extracting a certain quantity of fluid. Other important innovation is the fabrication of the whole device structure with SU-8 photoresist over a PCB. With this integration of technologies is possible to include microfluidics and electronics in the same low-cost LOC device. This design is conceived to be integrated in an array composed by several microextractors, biosensing devices and microneedles modules in order to obtain a LOC platform for biomedical applications.

Microfabrication technologies used for creating smart devices for industrial applications

Abstract: The purpose of this chapter is to provide the reader with a general overview of microsystems technology. It introduces the design and process flow in the microfabrication of a device: the materials used in the microfabrication, the essential microfabrication processes and the simulation tools involved in the design towards smart devices.