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1869 results in Biomedical engineering

Page 25 of 94

  • 6 - Electrodes, Sensors, Signals, and Noise

  • Barbara L. Christe, Indiana University–Purdue University, Indianapolis
  • Book:
    Introduction to Biomedical Instrumentation
    Published online:
    06 August 2018
    Print publication:
    07 December 2017, pp 66-80

  • Summary

    Introduction

    The most common activity in patient care is patient monitoring. The human body produces a variety of physiological signals, and physicians have learned to interpret these signals to provide information about the health of a patient. To measure or monitor these signals, there must be a connection between the patient and some (typically electronic) device. This type of activity is called in vivo monitoring, which refers to the living patient. This chapter will explore the machine– human connection.

    Sensors

    Sensors (often called transducers – the difference is unimportant here) convert the energy/ signal of the patient (pressure, for example) into a form that can be used by an instrument. There are two types of sensors/ transducers:

  • Passive sensors: Some devices change a passive electrical quality

  • in response to a change in surroundings. The output is a change in resistance, capacitance, or inductance. These variations can then be measured, often using Wheatstone bridge circuitry because the changes may be very small. Examples include:

  • Strain gauges– change in resistance when some external deflection or strain occurs. The change is due to the length of the device increasing, impacting resistance.

  • Potentiometer (variable resistors) – change in resistance when some external event occurs, usually some type of motion. Since these devices often have a mechanical knob or lever, they often convert mechanical movement or position into a change in resistance.

  • Thermistors – change in resistance when temperature changes.

  • Photoresistors– change in resistance in relation to the light levels surrounding the device.

  • Active sensors: Some devices p roduce a voltage or current in response to a change in environment. Examples include:

  • Piezoelectric crystals – produce a voltage as the crystal is compressed (even tiny amounts).

  • LVDTs (linear variable differential transformers) – convert linear motion (may be very small amounts) into an electrical signal.

  • Thermocouples – detect temperature differences using dissimilar metals. They require a known reference temperature.

    • When blood pressure is measured directly (in an artery), it is commonly measured using strain gauges, piezoelectric crystals, and silicon membranes. The hospital environment is very physically demanding on equipment. Even though transducers are usually used only once (disposable), a good transducer must be very durable.

  • 1 - A Career in the HTM Profession

  • Barbara L. Christe, Indiana University–Purdue University, Indianapolis
  • Book:
    Introduction to Biomedical Instrumentation
    Published online:
    06 August 2018
    Print publication:
    07 December 2017, pp 1-19

  • Summary

    What is the Name of this Career?

    Complex healthcare technology is utilized to support safe and effective patient care. Clinicians depend on devices to monitor and treat patients. Healthcare Technology Management (HTM) professionals are part of the healthcare team, utilizing technical expertise to ensure the safety, effectiveness, and availability of critical medical technologies including devices, applications, and software. The HTM discipline interweaves patient safety, medical technology, and financial stewardship as illustrated in Figure 1.1. HTM professionals collaborate with many groups within healthcare organizations including clinicians, risk management, information technology, facilities management, and administration.

    At different hospitals, HTM technicians may have a wide variety of job titles, including HTM technician or BMET. There are many definitions for what the letters BMET stand for – biomedical equipment technician, biomedical electronics technology, medical maintenance, biomedical engineering technologist, biomedical engineer, medical engineer, and medical equipment repair technician. In general, BMET or HTM technician may be used as title for a person with technical training who works in the clinical setting and supports the equipment involved in patient care.

    Technicians may be called the “biomeds,” “clinical engineers,” or the “equipment guys.” The name of the HTM- related department within a healthcare organization may vary but is often healthcare technology management, medical engineering, clinical engineering, or biomedical engineering. In some hospitals, HTM technicians may be responsible for everything from printers to computers to DVD players in the rooms of patients. In some hospitals, HTM technicians work for the maintenance departments and are dressed similarly to the maintenance workers. Other hospitals hire a wide range of technical staff who wear surgical scrubs, lab coats, monogrammed polo shirts, or dress shirts.

    Who Employs HTM Technicians?

    Generally, three groups of employers hire HTM technicians: hospitals, outside service providers, and the equipment manufacturers. Those who work for the hospital directly or an outside service organization (OSA) or independent service organization (ISO) may appear the same to clinical staff. Some employment issues (benefits, etc.) could be different, but the work- related duties are likely to be similar. Often, when employees work for a manufacturer, they are identified as field service representatives or FSRs. What do HTM Technicians do? Although the titles may vary, the core functions of HTM technicians are relatively consistent across patient care environments.

Liquid Cell Electron Microscopy
  • Edited by Frances M. Ross
  • Published online:
    22 December 2016
    Print publication:
    24 November 2016
  • The first book on the topic, with each chapter written by pioneers in the field, this essential resource details the fundamental theory, applications, and future developments of liquid cell electron microscopy. This book describes the techniques that have been developed to image liquids in both transmission and scanning electron microscopes, including general strategies for examining liquids, closed and open cell electron microscopy, experimental design, resolution, and electron beam effects. A wealth of practical guidance is provided, and applications are described in areas such as electrochemistry, corrosion and batteries, nanocrystal growth, biomineralization, biomaterials and biological processes, beam-induced processing, and fluid physics. The book also looks ahead to the future development of the technique, discussing technical advances that will enable higher resolution, analytical microscopy, and even holography of liquid samples. This is essential reading for researchers and practitioners alike.

Page 25 of 94