Biomedical Devices and Sensors (eBook)

J r me Molimard (Autor)

eBook Download: EPUB

2024
235 Seiten
Wiley (Verlag)
978-1-394-31716-5 (ISBN)

Infos

Monitoring the human body is a key element of digital health science. Low-cost sensors derived from smartphones or smartwatches may give the impression that sensors are readily available; however, to date, very few of them are actually medical devices.
Designing medical devices requires us to undertake a specific approach demanding special skills, as it concerns the integrity of the human body. The process is tightly framed by state regulations in order to ensure compliance with quality assessment, risk management and medical ethics requirements.
This book aims to give biomedical students an overview on medical devices design. It firstly gives a historical and economical approach, then develops key elements in medical device design with reference to EU and US regulations, and finally describes sensors for the human body. The clinical approach is presented as the central element in medical device qualification and this offers a perspective on the use of numerical simulation, particularly since its continued growth in the USA; despite the fact that the approach is strictly limited by regulations.

Jérôme Molimard is Professor at École des Mines Saint-Étienne, France. His research focuses on the mechanical interaction between medical devices and the human body through a crossdisciplinary approach between numerical modeling, experimental and clinical studies, in order to better understand their mode of action.

Textauszug

1
Medical Device: Definition, History and Economic Background

1.1. Definition

Everyday life in hospitals can provide as many examples of medical devices as necessary to convince someone of the diversity and the significant importance of this sector in modern medicine: hip prostheses, insulin pumps, pacemakers, magnetic resonance imaging (MRI) devices, as well as syringes, crutches, wheelchairs or dressings. Despite their diversity, they all belong to the category of medical devices. A definition can be extracted from the Regulation (EU) 2017/745 of the European Parliament and of the Council of April 5, 2017.

“Medical device” means any instrument, apparatus, appliance, software, implant, reagent, material or other article intended by the manufacturer to be used, alone or in combination, for human beings for one or more of the following specific medical purposes:

• diagnosis, prevention, monitoring, prediction, prognosis, treatment or alleviation of disease;
• diagnosis, monitoring, treatment and alleviation of, or compensation for, an injury or disability;
• investigation, replacement or modification of the anatomy or of a physiological or pathological process or state;
• providing information by means of in vitro examination of specimens derived from the human body, including organ, blood and tissue donations, and which does not achieve its principal intended action by pharmacological, immunological or metabolic means, in or on the human body, but which may be assisted in its function by such means.

The following products shall also be deemed to be medical devices:

• devices for the control or support of conception;
• products specifically intended for the cleaning, disinfection or sterilization of devices as referred to in Article 1(4) and in the first paragraph of this chapter.

As can be seen, the category of medical device is defined by its claim (human care, in a medical meaning) and by the means used (all means except pharmacological). It is interesting to see that software is mentioned in this definition, and thus, a piece of software that influences the medical process in some way is considered a medical device.

There is indeed a gray area between medical devices and other common devices. In this gray area lie most of the healthcare Internet of Things (IoT) gadgets or smartphone applications (e.g. cardiac monitoring, physical activity monitoring and brain sensing headbands). Most of these are not registered as medical devices and pretend to be sports or well-being applications, even if they target those who are anxious about their health and may suffer from chronic diseases. The quality of such measurement and/or processing, their influence on the customer’s health and the use of such amounts of personal data both by medical professionals or even private companies must be put into question by regulatory authorities as well as by the consumer themselves.

1.2. Examples of medical devices

The history of medical devices is directly related to that of techniques. It borrows from mechanics, optics, electronics and computer sciences and applies these to medicine. Surgeons in the Neolithic period performed brain surgery; copper dilators for urethral stenosis from the ancient Egyptians have been found; we could also refer to Mayan glasses. Should all of these be considered medical devices?

1.2.1. Surgery equipment

Audry and Ghislain (2009) consider that the history of modern medical devices begins in 1894 with E. Fournier, who commercialized the first syringe presenting industrial features, normalization and large diffusion. A few years later, in 1904, the “Dräger-Roth” inhalator, set-up in Germany, opened the way to modern anesthesia.

The hip prosthesis is a good example of advances in materials and material processing in a health application. At the beginning of the 20th century, surgeons tried to insert materials into the body to replace lost cartilage. But this created bio-compatibility or structure mechanics problems. The solution was found in the UK: totally replacing the joint. After an attempt with ivory, the first functional prosthesis using Chromium-Cobalt-Molybdenum alloy was proposed in 1936 by Dr. Bohlman, but there was a high friction coefficient, with a lot of wear particles diffused in the body. Polytetrafluoroethylene (PTFE) appeared in 1959 and in the 1970s Prof. Boutin proposed a total hip replacement with a ceramic head. In the same period, Prof. G. Bousquet improved mobility by adding a second degree of freedom to hip prosthesis with the concept of double mobility prosthesis, reducing the risk of dislocation.

The fight against strokes was one of the biggest adventures for humans in the second half of the 20th century and medical devices were the weapons of cardiac surgeons forged by engineers. In 1950, J. Hoops developed the first prototype of the pacemaker. This model was cumbersome and not easy to live with because it was external and required a power supply. The first internal pacemaker was developed and implanted a few years later, in 1958, by Drs. R. Elmqvist and A. Senning in Sweden. In fact, during the 1950s, many independent projects came out in Europe and North America.

This period saw many advances in bio-materials, and some of these resulted in important applications in cardiology. For example, Prof. A. Carpentier developed the first bio-prosthesis: the human mitral valve was replaced by a bio-prosthesis based on a valve from a pig. The original system wore off after few years; now, the third generation lifespan is 25 years. During the 1970s and the 1980s, electronic engineering allowed for the miniaturization of all of the systems. In 2008, after many years of research, Carpentier started the Carmat company, which developed a totally artificial heart, taking advantage of the previous developments in cardiac regulation for pacemakers, but also bio-materials, in particular animal-based materials. The first implantation of a totally artificial heart succeeded in 2013.

Miniaturization of medical devices totally changed the way in which surgeons practiced operations. In 1973, Profs. Bruhat and Manhes achieved the first endoscopic surgery of an extra-uterine pregnancy in Clermont-Ferrand (France). Since then, the advances in microelectronics, medical imaging and augmented reality have made endoscopic surgery possible in many fields: general surgery, urology or even cardiac surgery, with endoscopic placement of stents or cardiac valves. This new paradigm in surgery strongly decreases the invasiveness of surgery and thus increases the chance of the patient’s recovery, limits the side effects of the surgery and finally decreases the overall medical cost.

Finally, insulin pumps are another interesting example of a medical device, which have become the gold standard for chronic diseases. The innovation came from Germany, with glycemia measurement units proposed in 1969, and 10 years later, we saw the first pump. The technical problem that lay behind this is the insulin regulation that controls the patient’s diabetes. Now, both the measurement unit and pump are miniaturized enough to be implanted into the human body. The last step is to connect the measurement to the pump controller, but this raises more than just technical questions: what would happen in the case of a problem? Who is ultimately responsible for the care?

1.2.2. Medical imaging

Perhaps the biggest change in medical practices over the 50 past years is medical imaging.

W. Röntgen discovered X-ray radiations in 1895 in Germany. Although he was following some pioneers’ works, he was the first to publish material on it. He discovered that X-rays pass through solids. After making an image of a woman’s hand, he understood the great interest of X-rays in medicine. The technique spread very quickly: the first surgery under X-rays was performed by J. Hall-Edwards only 1 year later in the UK, and in 1896 a Georgian physician I. Tarkhanishvili discovered that X-rays affect metabolism. Soon after, side effects were reported: hair loss, burns, etc. An early researcher developed a type of cancer due to the radiation produced by X-rays and died in 1904. Advances in X-ray generation and detection saw a perambulation in the history of modern physics, with names such as M. von Laue, W.L. Bragg or W.E. Bragg. We ended up with W. Coolidge who invented X-ray tubes with a continuous emission in 1913 and M. Skłodowska-Curie, who, in 1914, developed mobile radiography units for soldiers in World War I (Figure 1.1). Medical imaging using X-rays is based on the absorption properties of high atomic numbers such as calcium, which provokes a contrast. Bone or dental imaging is straightforward; what is more, after calibration, the bone density can be directly deduced from image intensity maps. Cardiovascular imaging is possible using contrast agents. In this 2D projection form, X-rays are used for dental applications, detection of skeleton problems, but also in the diagnosis of various diseases (pneumonia, lung cancer, pulmonary edema, bowel obstruction, gallstones, kidney stones, etc.), or for implant follow-ups. One image only is a conical projection; by taking various images at different points of view, it is possible to back-project the X-rays (Radon transform) and to reconstruct the whole volume. Of course, the cost for that is higher irradiation and some very recent advances could reduce this...

Produkt-Details

• Erscheint lt. Verlag: 4.9.2024
• Sprache: englisch
• Themenwelt: Medizin / Pharmazie ► Gesundheitsfachberufe
• Themenwelt: Medizin / Pharmazie ► Medizinische Fachgebiete
• Themenwelt: Technik
• Schlagworte: biomedical devices • biomedical senors • biomedicine • Body Monitoring • digital health science • Health Monitoring • medical device design • Medical Devices • Medical Ethics • Regulation
• ISBN-10: 1-394-31716-6 / 1394317166
• ISBN-13: 978-1-394-31716-5 / 9781394317165