Design Of Biomedical Systems Research Articles

THE HUMAN FACTOR ISSUES IN BIOMEDICAL SYSTEMS

The consequence of insufficient attention of specialists to the human factor in the development of biomedical technologies is the lack of awareness of biomedical engineering students with the cognitive aspects of human-machine interaction, which does not allow the design of safe and reliable biomedical systems. The paper shows the need to consider the human factor at all stages of the life cycle of biomedical systems and the need to introduce a discipline dedicated to the phenomenon of the human factor into the training program for biomedical engineers. Thus, the consequence of the development of biotechnologies is the necessity for teaching students to consider the human factor at all stages of the biomedical technologies life cycle. The motivation is to bridge the gap between the theoretical concepts proposed to eliminate human factors problems in the modelling and design of biomedical systems and the practical implementation of human activities in them. It is necessary to consider the issues that may arise due to the human factor in the operation of biomedical systems in order to move forward in solving these problems.

Effects of a particle placed on the ossicles for microphoneless cochlear implant design.

In a typical cochlear implant design, the ambient sound is detected via a microphone and the transmission unit of the implant is placed at the back of the auricle. However, this design has several drawbacks. Firstly, the subject cannot bath or swim comfortably with the microphone unit on, and secondly having an external attached unit which may be visible is cosmetically disturbing. Herein, the idea is to explore obtaining the acoustic signals that would directly drive the cochlear nerves, without using a microphone, in which only the vibrations of the ossicles are employed. Thus, the natural filter caused by the anatomy of the ear may be maintained. The proposed method is to place or attach a micro-electro-mechanical-system (MEMS) type of tiny and lightweight accelerometer to sense or detect the vibrations of ossicles, namely malleus, incus and stapes. A quick analysis or first-thought revealed that physically longer extension of the incus is the most suitable and/or convenient place to attach such a sensor. The model adopted has been optimized to match the amplitude and phase response of the human ear from a system analysis point of view. Some simulation experiments had been done to study and understand the possible loading effects of placing a sensor on the incus. Purpose of the simulations is testing the feasibility before the very difficult surgical procedures. Preliminary results indicate that placing a sensor of weight up to 36 mg does not seriously affect the amplitude and the phase response of the ear. This study is yet another example of how simulations of physiological systems can be advantageous and facilitating in the design of biomedical systems.

Compact and Unidirectional Resonance-Based Reflector Antenna for Wideband Electromagnetic Imaging

A unidirectional and wideband resonance-based reflector (RBR) antenna that can be used for biomedical applications, such as thorax imaging, is proposed. One of the main limitations in the design of biomedical systems, which utilize multiple densely spaced antennas, is the mutual coupling created by the radiating elements and the surface waves (SWs). The proposed RBR antenna is designed to achieve an in-phase reflection phase within a wide operating bandwidth. Moreover, it suppresses the SW propagation that reduces the overall mutual coupling by up to 12 dB across the whole operating bandwidth. It consists of a resonance-based loop reflector that is positioned in a perpendicular configuration to a wideband dipole antenna. To increase the electrical size of the loop reflector without physically altering the dimensions of the substrate, its structure is meandered, and a compact side size of $0.22\lambda \times 0.22\lambda $ , which is more than 50% smaller than recent RBR antennas, is achieved. Unlike the majority of conventional double-layer high-impedance surfaces, the proposed RBR antenna consists of a single layer and a single unit cell and utilizes the actual dipole antenna element to achieve a measured wideband unidirectional radiation from 0.83 to 1.9 GHz (79%) with a peak gain of 3.8 dBi and a front-to-back ratio of 9 dB. Due to negligible electromagnetic coupling between RBR antennas, lateral SWs are suppressed, and thus multiple antennas can be located adjacent to each other without experiencing any frequency shift or impedance mismatch.

Pupillary transient responses to within-task cognitive load variation

Changes in physiological signals due to task evoked cognitive load have been reported extensively. However, pupil size based approaches for estimating cognitive load on a moment-to-moment basis are not as well understood as estimating cognitive load on a task-to-task basis, despite the appeal these approaches have for continuous load estimation. In particular, the pupillary transient response to instantaneous changes in induced load has not been experimentally quantified, and the within-task changes in pupil dilation have not been investigated in a manner that allows their consistency to be quantified with a view to biomedical system design. In this paper, a variation of the digit span task is developed which reliably induces rapid changes of cognitive load to generate task-evoked pupillary responses (TEPRs) associated with large, within-task load changes. Linear modelling and one-way ANOVA reveals that increasing the rate of cognitive loading, while keeping task demands constant, results in a steeper pupillary response. Instantaneous drops in cognitive load are shown to produce statistically significantly different transient pupillary responses relative to sustained load, and when characterised using an exponential decay response, the task-evoked pupillary response time constant is in the order of 1–5 s. Within-task test–retest analysis confirms the reliability of the moment-to-moment measurements. Based on these results, estimates of pupil diameter can be employed with considerably more confidence in moment-to-moment cognitive load estimation systems.

Teaching biomedical design through a university-industry partnership.

This paper describes a course that, as a result of a university-industry partnership, emphasizes bringing industry experts into the classroom to teach biomedical design. Full-time faculty and industry engineers and entrepreneurs teach the senior technical elective course, Biomedical System Design. This hands-on senior course in biomedical system design places varied but connected emphasis on understanding the biological signal source, electronics design, safety, patient use, medical device qualifications, and good manufacturing practices.

The Use of Dynamic Systems Based on Shape Memory Alloys for the Treatment of Neuromuscular Disorders

Shape Memory Alloys (SMA) are very versatile materials that display a number of unusual and interesting properties, in particular, pseudoelasticity, thermally-activated shape memory, mechanical and thermal hysteresis. All of these characteristics can be thought of as sources of inspiration in the development of dynamic systems for mechanical or mechatronic applications. This paper will focus on several results obtained in the field of Neuromuscular Rehabilitation and Neurology. The need to customise functions, to make devices lightweight, portable and suitable to be interfaced with modern diagnostic instrumentation, and a drive towards the development of technologies appropriate for home-based therapies are the reasons why employing SMA in the design of biomedical systems for the treatment of neuromuscular disorders can show all the advantages of solid-state actuation and sensing.