A wearable passive force sensor/active interrogator intended for intra-splint use for the detection and recording of bruxism

A wearable bite force sensing system proto type made up of a passive force sensor and an active interrogator/reader is described. The system is aimed a* bite sensing using a wireless link between the passive sensor to be located in (lie moutb and the external interrogator that can record the evolution of detected force. The interrogator generates a magnetic field that energizes the passive sensor which is also used as the information transmission earlier. The passive farce sensor does not need a battery to operate it because it can extract the energy it needs to operate fmin the carrier field generated by the interrogator. Occlusal force quantification can be used for the detection of bruxing episodes and registration. The small size of the components used (sind) and its further size reduction if they are integrated would allow an implant the size of a tooth

Rapid prototyping of multi-scale biomedical microdevices by combining additive manufacturing technologies

The possibility of designing and manufacturing biomedical microdevices with multiple length-scale geometries can help to promote special interactions both with their environment and with surrounding biological systems. These interactions aim to enhance biocompatibility and overall performance by using biomimetic approaches. In this paper, we present a design and manufacturing procedure for obtaining multi-scale biomedical microsystems based on the combination of two additive manufacturing processes: a conventional laser writer to manufacture the overall device structure, and a direct-laser writer based on two-photon polymerization to yield finer details. The process excels for its versatility, accuracy and manufacturing speed and allows for the manufacture of microsystems and implants with overall sizes up to several millimeters and with details down to sub-micrometric structures. As an application example we have focused on manufacturing a biomedical microsystem to analyze the impact of microtextured surfaces on cell motility. This process yielded a relevant increase in precision and manufacturing speed when compared with more conventional rapid prototyping procedures

Deep reactive ion etching of auxetic structures: present capabilities and challenges

Auxetic materials (or metamaterials) have negative Poisson ratios (NPR) and display the unexpected properties of lateral expansion when stretched, and equal and opposing densification when compressed. Such auxetic materials are being used more frequently in the development of novel products, especially in the fields of intelligent expandable actuators, shape-morphing structures, and minimally invasive implantable devices. Although several micromanufacturing technologies have already been applied to the development of auxetic materials and devices, additional precision is needed to take full advantage of their special mechanical properties. In this study, we present a very promising approach for the development of auxetic materials and devices based on the use of deep reactive ion etching (DRIE). The process stands out for its precision and its potential applications to mass production. To our knowledge, it represents the first time this technology has been applied to the manufacture of auxetic materials with nanometric details. We take into account the present capabilities and challenges linked to the use of DRIE in the development of auxetic materials and auxetic-based devices

Comparative study of auxetic geometrics by means of computer-aided design and engineering

Auxetic materials (or metamaterials) are those with a negative Poisson ratio (NPR) and display the unexpected property of lateral expansion when stretched, as well as an equal and opposing densification when compressed. Such geometries are being progressively employed in the development of novel products, especially in the fields of intelligent expandable actuators, shape morphing structures and minimally invasive implantable devices. Although several auxetic and potentially auxetic geometries have been summarized in previous reviews and research, precise information regarding relevant properties for design tasks is not always provided. In this study we present a comparative study of two-dimensional and three-dimensional auxetic geometries carried out by means of computer-aided design and engineering tools (from now on CAD–CAE). The first part of the study is focused on the development of a CAD library of auxetics. Once the library is developed we simulate the behavior of the different auxetic geometries and elaborate a systematic comparison, considering relevant properties of these geometries, such as Poisson ratio(s), maximum volume or area reductions attainable and equivalent Young's modulus, hoping it may provide useful information for future designs of devices based on these interesting structures

The Kahawa Declaration: a manifesto for the democratization of medical technology

Most medical technology is employed and accepted passively by patients and doctors who have little or no influence in its design or usability. Patients are not involved in the development of medical technology, which is undertaken behind closed doors and whose global impact is hindered by proprietary know-how and by costs. This has so far impeded equitable healthcare as most of the world does not have access to the technology or healthcare coverage. Understanding the relevance of international partnerships for achieving the Sustainable Development Goals, feeling specially committed to the promotion of the Goal on “Good Health and Well-Being”, and convinced about the role that open-source biomedical engineering approaches may play in the future of medical technology, we commit ourselves, through the Kahawa Declaration, to enlighten the transformation of the biomedical engineering field, towards the democratization of medical technology as a key for achieving universal equitable health care. This paper presents the content of the Kahawa Declaration, which was signed in Nairobi in December 2017

Promotion of professional skills in engineering education: strategies and challenges

Basic engineering skills are not the only key to professional development, particularly as engineering problems are everyday more and more complex and multifaceted, hence requiring the implementation of larger multidisciplinary teams, in many cases working in an international context and in a continuously evolving environment. Therefore other outcomes, sometimes referred to as professional skills, are also necessary for our students, as most universities are already aware. In this study we try to methodically analyze the main strategies for the promotion of professional skills, mainly linked to actuations which directly affect students or teachers (and teaching methodologies) and which take advantage of the environment and available resources. From an initial list of 51 strategies (in essence aimed at promotion of different drivers of change, linked to students, teachers, environment and resources), we focus on the 11 drivers of change considered more important after an initial evaluation. Subsequently, a systematic analysis of the typical problems linked to these main drivers of change, enables us to find and formulate 12 major and usually repeated and unsolved problems. After selecting these typical problems, we put forward 25 different solutions, for short-term actuation, and discuss their effects, while bearing in mind our team’s experience, together with the information from the studies carried out by numerous teaching staff from other universities

Polymeric Piezoelectric Sensors and Remote Communication for Detection of Bruxism

Active materials are capable of responding in a controlled way to different external physical or chemical stimulus by changing some of their properties. These materials can be used to design and develop sensors, actuators and multifunctional systems with a large number of applications for developing medical devices (for both surgery and implants). On the other hand, Bruxism is a health problem consisting on grinding or tightly clenching the upper and lower teeth, and both phenomena lead to wear of the teeth and produce a noise during the night that is sufficiently loud to disturb the sleep of anyone sharing the bedroom. The tension produced also causes problems in the muscles, tissues and other structures surrounding the jaw, ear pain, headaches, lesions to the teeth and disorders in the jaw joints. For an early, rapid, effective and economical diagnosis of bruxism, we propose the use of instrumented splints based on the use of active materials, in order to detect and record the intensity and duration of interdentally pressure episodes. This paper introduces the design, manufacture and testing of using instrumented splint for diagnosing bruxism. The contribution of this work basically focus on using piezoelectric polymeric sensors, taking advantage of their reduced thickness, and avoiding the alteration of the patient¿s bite. In addition, the system allows a quantitative assessment of intraoral pressure that consequently allows the diagnosis of bruxism behaviour at an early stage, aiming to perform corrective actions before irreversible dental wear appears. The first trials performed allowed to demonstrate the feasibility of the system, which also includes wireless communication capabilities for improving telemedicine tasks

Physical ageing of a PU based shape memory polymer: influence on their applicability to the development of medical devices.

The variation in the properties of polymeric materials through ageing has considerable implications, since it affects the performance of any associated devices. Specially in the case of implantable devices with shape memory, any change in the switching temperature can give rise to problems in the thermal activation of the geometrical changes necessary to treat certain pathologies.This paper presents a study about the physical ageing of a polyurethane based shape memory polymer, SMP, at different temperatures using differential scanning calorimetry, DSC, and microhardness, MH, tests. The benefits of the combinated application of both testing techniques is shown, since DSC tests give information on the evolution of the glass transition temperature and the MH tests provide details of changes regarding mechanical properties

Cálculo de la resistencia a la fatiga superficial en superficies con lubricación elastohidrodinámica mediante el criterio de Dang Van

Los fenómenos de fatiga superficial en sus diferentes escalas (micropitting, pitting, spalling), aparecen en multitud de elementos mecánicos en contacto lubricado como pueden ser los engranajes o rodamientos o en elementos con contacto seco como son las ruedas de ferrocarril. Los defectos que aparecen en las superficies en contacto debidos a estos fenómenos empeoran las condiciones de funcionamiento, provocando vibraciones, desgaste prematuro y en los casos más extremos el fallo de la máquina. El procedimiento que se sugiere en este artículo se inicia con el cálculo de los parámetros que definen el contacto elastohidrodinámico y que tienen influencia en la resistencia a fatiga del contacto: espesor de película, distribución de presión y coeficiente de fricción. Una vez se tiene la presión y el coeficiente de fricción en la superficie de contacto, se procede al cálculo de las tensiones en el interior del material obteniendo la distribución de tensiones. Conocidas las tensiones en todo punto interior y el proceso de carga completo se aplica el criterio de fatiga de Dang Van y se verifica si existe, o no, probabilidad de fallo por fatiga. El criterio de Dang Van es aplicable para el cálculo de la vida a fatiga para un alto número de ciclos (donde el tiempo de propagación de grieta es despreciable frente al tiempo de iniciación) y se basa en la aproximación a la escala mesoscópica y la existencia de un plano crítico. Una vez descrita la teoría se propondrá una aplicación para el cálculo de tensiones en contactos puntuales y contactos lineales y el análisis de fatiga superficial en engranaje

Models for predicting friction coefficient and parameters with influence in elastohydrodynamic lubrication

This article shows different friction prediction models applicable to lubricants in point contacts under an elastohydrodynamic regime. The types of models used are two variations of the Newtonian theory, the Limiting Shear Stress model and the one based on Carreau's equation. The article sets out the theoretical calculation procedures and the ensuing equations for calculating the friction coefficient. The aims of the article are to study the effect of the parameters with influence on friction and to compare the model's results with those given by an experimental stage performed on a mini traction machine. This test system allows the measurement of friction coefficient in point contacts (ball–disc) under a wide range of variation of parameters such as temperature, slide-roll ratio, lubricant, material, load, or velocity