A new set of manufacturing technologies has emerged in the past decades to address market requirements in a customized way and to provide support for research tasks that require prototypes. These new techniques and technologies are usually referred to as rapid prototyping and manufacturing technologies, and they allow prototypes to be produced in a wide range of materials with remarkable precision in a couple of hours. Although they have been rapidly incorporated into product development methodologies, they are still under development, and their applications in bioengineering are continuously evolving. Rapid prototyping and manufacturing technologies can be of assistance in every stage of the development process of novel biodevices, to address various problems that can arise in the devices' interactions with biological systems and the fact that the design decisions must be tested carefully. This review focuses on the main fields of application for rapid prototyping in biomedical engineering and health sciences, as well as on the most remarkable challenges and research trends.

Intraoral devices for bite-force sensing have several applications in odontology and maxillofacial surgery, as bite-force measurements provide additional information to help understand the characteristics of bruxism disorders and can also be of help for the evaluation of post-surgical evolution and for comparison of alternative treatments. A new system for measuring human bite forces is proposed in this work. This system has future applications for the monitoring of bruxism events and as a complement for its conventional diagnosis. Bruxism is a pathology consisting of grinding or tight clenching of the upper and lower teeth, which leads to several problems such as lesions to the teeth, headaches, orofacial pain and important disorders of the temporomandibular joint. The prototype uses a magnetic field communication scheme similar to low-frequency radio frequency identification (RFID) technology (NFC). The reader generates a low-frequency magnetic field that is used as the information carrier and powers the sensor. The system is notable because it uses an intra-mouth passive sensor and an external interrogator, which remotely records and processes information regarding a patient's dental activity. This permits a quantitative assessment of bite-force, without requiring intra-mouth batteries, and can provide supplementary information to polysomnographic recordings, current most adequate early diagnostic method, so as to initiate corrective actions before irreversible dental wear appears. In addition to describing the system's operational principles and the manufacture of personalized prototypes, this report will also demonstrate the feasibility of the system and results from the first in vitro and in vivo trials.

This article presents analytical friction prediction models applicable to lubricants in point contacts under thermal elastohydrodynamic lubrication (TEHL). The types of models used consider the heat generated and its penetration into the bulk of the contacting solids. Therefore, the increase in temperature is determined, which causes important variations in the operating conditions. The article sets out the hypotheses assumed, the theoretical calculation procedures and the ensuing equations for determining the friction coefficient under TEHL. An experimental stage is performed on a mini-traction-machine, which allows the measurement of friction coefficient in ball–disc contacts under a wide range of control parameters involved in TEHL, such as lubricant bath temperature, load, average velocity, slide-to-roll ratio, and contacting materials. The experimental results for different lubricants are compared to those given by the models, and show the proposed models to be accurate for predicting the friction coefficient.

This study is focused on obtaining intelligent structures manufactured from shape memory polymers possessing the ability to change their geometry in successive or 'step-by-step' actions. This objective has been reached by changing the conventionally used shape memory activation systems (heating resistance, laser or induction heating).The solution set out consists in using Peltier cells as a heating system capable of heating (and activating) a specific zone of the device in the first activation, while the opposite zone keeps its original geometry. By carefully reversing the polarity of the electrical supply to the Peltier cell, in the second activation, the as yet unchanged zone is activated while the already changed zone in the first activation remains unaltered.We have described the criteria for the selection, calibration and design of this alternative heating (activation) system based on the thermoelectric effect, together with the development of different 'proof of concept' prototypes that have enabled us to validate the concepts put forward, as well as suggest future improvements for 'intelligent' shape memory polymer-based devices.

Surface texturing has proved to be a very useful tool for expanding the behaviour under hydrodynamic and elastohydrodynamic regimes instead of mixed or boundary lubrication regimes, and therefore for reducing the friction coefficient under high-load low-speed conditions. This article presents the texturing of different copper test-samples using photolithography and chemical etching to measure the friction coefficient using a point contact machine. The effects of texture size, texturing density, the initial roughness of the samples and the operating conditions have all been studied. Some combinations of texturing density and texture size achieve up to 30% reduction in the friction coefficient. Taking into account experimental data, artificial neural networks are used as a tool for both predicting and optimising the friction coefficient on the textured surface for any given operating condition.