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In this paper, a procedure to release SU-8 layers from glass substrates using typical undesirable effects is described. The proposed process can be used as lift off or stripping. The releasing method consists in taking advantage of the undesired thermal delamination, and the effect of UV overexposure on the delamination temperature, which are considered undesirable effects. This implies the use of SU-8 for both structural and lift off using the same facilities, without any additional photoresist, material, remover or developer. In this way, the fabrication of a glass/gold microelectrodes array (MEA) for cell culture applications is carried out as a proof of concept. The MEA is composed of gold tracks of 1.5 mm width and 8 electrodes with radii between 25 and 500 μ m at its ends. The SU-8 photoresist is also used as an insulation layer releasing the pads and the electrodes. Finally, biological experiments with neuroblastoma cells SK-N-SH cultured on the MEA surface were carried out in order to validate and demonstrate the biocompatibility of both the MEA and the process. The fabrication and biological results were successful, showing a normal cell proliferation over the developed MEA. [ABSTRACT FROM AUTHOR]

The field of industrial electronics has evolved profoundly during recent decades, hand in hand with smart systems, enabling the development of new functionalities. It is now common for robots to perform many previously burdensome tasks and operate in collaboration with humans. Miniaturized sensors, which are capable of extracting industrial process data with high levels of accuracy and robustness, are fully integrated to increment efficiency. Motion control systems have enabled the adaptation of systems to harsh industrial conditions, and all data related to sensing, operation, and control are interconnected using communication networks. Fault diagnosis strategies provide feasible control actions when abnormalities are detected. These are just a few examples that illustrate a revolution that has enabled the incorporation of smart systems into industrial processes. This article discusses how the incorporation of these capabilities has been made possible, and it examines the future challenges to further advances. [ABSTRACT FROM AUTHOR]

In this paper, a method of integration of silicon sensors in microfluidic platform is presented. In particular, impedimetric silicon sensors are used to make the proof of concept. These sensors are integrated in a FR4 substrate [component of a printed circuit board (PCB)] where the SU-8 microfluidic circuit is built. In order to generalize the application of this method, standard processes that are typical in the laboratories are used. The material to fabricate those microfluidic circuits is the negative photoresist SU-8. The method of fabrication consists on performing the typical SU-8 process over the silicon chips once they are inserted in the FR4 substrate. This method must provide flatness to avoid irregular microchannels. Also, the proposed process must ensure the insulation of the electric connections to avoid short-circuits when the sample fluid flows through the systems, and bondings robust enough to support a spinning step. In addition, the SU-8 process must be clean enough to keep the capability of measurement of the sensors. This cleanness has been studied using different conductivities of a KCl solution, providing good results. Finally, apart from integrating microfluidic and electronics in the same substrate, this method of integration provides an approach to the optimum between low cost, simplicity and precise measurements thank to the use of inexpensive PCB-based platforms and precise silicon sensors. [ABSTRACT FROM AUTHOR]

A depressurisation method to build SU-8 chambers as pneumatic energy reservoirs is described. The method consists in a combination of injection/extraction of uncrosslinked SU-8 and its exposure in different steps, intended to set the pressure of a chamber below atmospheric. These chambers are intended to be integrated with an actuation system to perform the extraction of fluids from the outside to the inside of a microfluidic SU-8 lab-on-a-chip. This method improves the portability of the platform because external pumps used to impulse the fluids can be avoided. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Printed circuit board (PCB) technology is well known, reliable, and low-cost, and its application to biomedicine, which implies the integration of microfluidics and electronics, has led to Lab-on-PCB. However, the biocompatibility of the involved materials has to be examined if they are in contact with biological elements. In this paper, the solder mask (PSR-2000 CD02G/CA-25 CD01, Taiyo Ink (Suzhou) Co., Ltd., Suzhou, China) of a commercial PCB has been studied for retinal cultures. For this purpose, retinal explants have been cultured over this substrate, both on open and closed systems, with successful results. Cell viability data shows that the solder mask has no cytotoxic effect on the culture allowing the application of PCB as the substrate of customized microelectrode arrays (MEAs). Finally, a comparative study of the biocompatibility of the 3D printer Uniz zSG amber resin has also been carried out. [ABSTRACT FROM AUTHOR]

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 micro- electromechanical 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Although prostate cancer is one of the most common cancers in the male population, its basic biological function at a cellular level remains to be fully understood. This lack of in depth understanding of its physiology significantly hinders the development of new, targeted and more effective treatment strategies. Whilst electrophysiological studies can provide in depth analysis, the possibility of recording electrical activity in large populations of non-neuronal cells remains a significant challenge, even harder to address in the picoAmpere-range, which is typical of cellular level electrical activities. In this paper, we present the measurement and characterization of electrical activity of populations of prostate cancer cells PC-3, demonstrating for the first time a meaningful electrical pattern. The low noise system used comprises a multi-electrode array (MEA) with circular gold electrodes on silicon oxide substrates. The extracellular capacitive currents present two standard patterns: an asynchronous sporadic pattern and a synchronous quasi-periodic biphasic spike pattern. An amplitude of ±150 pA, a width between 50–300 ms and an inter-spike interval around 0.5 Hz characterize the quasi-periodic spikes. Our experiments using treatment of cells with Gd3⁺, known as an inhibitor for the Ca2⁺ exchanges, suggest that the quasi-periodic signals originate from Ca2⁺ channels. After adding the Gd3⁺ to a population of living PC-3 cells, their electrical activity considerably decreased; once the culture was washed, thus eliminating the Gd3⁺ containing medium and addition of fresh cellular growth medium, the PC-3 cells recovered their normal electrical activity. Cellular viability plots have been carried out, demonstrating that the PC-3 cells remain viable after the use of Gd3⁺, on the timescale of this experiment. Hence, this experimental work suggests that Ca2⁺ is significantly affecting the electrophysiological communication pattern among PC-3 cell populations. Our measuring platform opens up new avenues for real time and highly sensitive investigations of prostate cancer signalling pathways. [ABSTRACT FROM AUTHOR]