A prototype for mechanizing the asphalt roofing process was developed. In this manuscript, we present the design, manufacturing, preliminary thermal test, and operation test of the equipment. The innovation is sustained by the use of infrared radiators instead of fuel burners. Infrared heaters provide optimal clean heat transfer to asphalt rolls in comparison to fuel burner automated systems since the latter generates a significant amount of CO2, SO2, and other non-ecofriendly emissions close to workers. Moreover, the equipment has several advantages with respect to manual installation, such as roofing capacity, cleanness, safety, uniformity, and environment-friendliness. It demonstrates an installation speed of 1 m/min, on average, for 3 kg/m2 rolls, which leads to around 400–420 m2 per person a day, more than the usual manual roofing rate. However, there are some issues that need to be resolved, such as inaccurate unrolling and/or bad adhesion gaps.

This paper theoretically analyses the miniaturization effects on torque, efficiency and thermal behaviour of high torque permanent magnet BLDC motors with ferromagnetic core coils for internal medical devices. Using a finite element model of a 2-phase BLDC motor, scalability laws are provided for diameters between 0.1 and 100 mm and current densities between 1 and 1000 A/mm2. Based in the impact of the cogging torque and overheating of the motor, scale dependent operational limits are calculated. Operational threshold can be determined at the point where cogging torque becomes dominating over total torque, limiting the use of traditional iron-core motors in the micro-scale. To overcome such limitation, a potential solution is to increase the current density in the windings. However, overheating of the motor limits such increase in the current density which is critical for internal medical applications. Current density limits are provided based on three representative in-body thermal scenarios: respiratory tract, body fluid and blood torrent. Maximum current densities and corresponding torque and efficiency have been obtained for different micro-motor sizes considering safe in-body operation as threshold. It is demonstrated the potential application of micro-motors in internal body environments with acceptable performance for sizes down to 0.1 mm diameter.

Multilayered microcoils are of great importance for the development of advanced electromagnetic microactuators and especially important to develop high sensitivity microsensors and magnetic field neural stimulators for medical applications. A clean room-free procedure for manufacturing multilayered micrometric coils is presented in this work. The production of miniaturized multilayered coils from tens to hundreds of micrometres long is demonstrated. The microcoils have outer diameters ranging between 150 and 300 µm, arrangements of up to 5 consecutive layers, and an average fill factor of 85%. This means 3 times smaller diameters than the smallest diameter ever achieved by winding techniques while keeping a high fill factor and a large number of layers. Such small and highly performant microcoils have never been demonstrated neither by winding processes nor epitaxial growth techniques. These microcoils were tested inside different human body-like environments. Maximum current density vs. temperature was measured in air, fat tissue, muscle tissue and simulated body fluid at 36 °C. A maximum current density of 3600 A/m 2 has been measured before coil failure. Experiments demonstrated that current densities up to 610 A/m 2 can safely be supplied to coils without risk of harm to internal tissues. These counterintuitive values are orders of magnitude larger than typical current densities used in macroscale actuators windings. 1

A miniaturized helical antenna is presented in this work. The antenna is flexible, it is 6100 μm long and it has a diameter of 352 μm. This antenna has such a small cross-section, that permits to be implanted in the human body with fine syringes and minimally invasive surgeries. The antenna can be used to receive power and/or send information in medical devices. The antenna is made of biocompatible materials: polytetrafluoroethylene (PFTE) and copper. The fundamental parameters of the antenna have been simulated and experimentally measured in animal human-like tissues, showing good agreement. The resonant frequency of the antenna is 4.7 GHz, with a reflection coefficient of -25.1 dB, and a gain of -4.7 dBi. As expected, the resonant frequency decreases inside biological tissues comparing to the free-space open-air measurement. Reducing the resonant frequency is an advantage because power signals can penetrate deeper into body tissues.

In this work, we describe the design and test of a new piece of equipment, developed in order to enhance speed, gas consumption and safety during the manual asphalt roofing process. The novelty of the equipment is based on the use of a set of five parallel gas burners located in front of the roll to maximize heat transfer. The equipment is light and can be used by any worker on any type of roof. It also includes a thermal insulation cover to significantly reduce gas consumption and, thus, to reduce CO2, SO2, and other non-eco-friendly emissions. In this paper, we present the mechanical and thermal design and analysis of the equipment, Computer Fluid Dynamics (CFD) simulations for heat transfer calculation, a description of the manufacturing and assembly, a preliminary thermal test, and an operational test. The results demonstrate an installation speed of 1.75 m2/min, for 3 kg/m2 rolls, which translates to around 700–735 m2 per person per day, more than twice the usual manual roofing rate. Nevertheless, some issues need to be resolved, such as the nonuniform heat distribution and the low heat transfer at the end of the roll installation.