Ricerc@Sapienza

The aim of the TAU project is to develop a functional glass substrate with integrated thin-film heaters and thin-film temperature sensors to be used for the accurate and localized temperature control of lab-on-chip devices for space applications.
Lab-on-chip devices are indeed ideal candidates for the use in space missions where experiment automation, system compactness, limited weight and low sample and reagent consumption are required. In this context, precise temperature control is a fundamental requirement for most of the bioanalytical tasks that must be carried out during the experiments. Temperature control, however, represents one of the most power consuming tasks if conventional approaches are considered.
The proposed active glass substrate is meant to be used as cover-glass for the sealing of microfluidic chips and it will offer an optimized and energy efficient solution for the thermal control of microfluidic devices. The main requirements include: good optical transparency to allow the use of optical analytical methods on the lab-on-chip; an accurate measurement of the local chip temperature; uniform heating of the target lab-on-chip area. These requirements will be met by combining a transparent thin-film heater and a set of hydrogenated amorphous silicon (a-Si:H) p-i-n diodes fabricated on the same glass substrate. The transparent resistive heater will be made of Indium Tin Oxide (ITO) deposited by RF magnetron sputtering. Due to the negligible Thermal Coefficient of Resistance of ITO films, the measurement of the temperature cannot be accomplished through resistance measurements as for metallic heaters. For this reason, a-Si:H diodes deposited by Plasma Enhanced Chemical Vapor Deposition (PECVD) will be used for accurate temperature measurement. The layout of heaters and sensors will be optimized to achieve a uniform temperature profile over the area of interest and to maximize the energy efficiency by heating only the volume of interest of the chip.