Biomedical Instruments: An Overview

Introduction to Biomedical Instruments

• Biomedical instruments include a wide array of devices and systems.
• An ECG machine, chemical biosensor, and medical imaging system are all examples of biomedical instruments.
• The worldwide market for biomedical instruments is estimated to be over $200 billion.
• Biomedical instruments are essential in many medical and scientific fields.

Basic Model of Instrumentation Systems

• Biomedical instruments can be modeled using a simple diagram including sensors, actuators, an electronics interface, and computation.

Sensors and Actuators

• A sensor must detect biochemical, bioelectrical, or biophysical parameters, reproduce the physiologic time response of these parameters, and provide a safe interface with biological materials.
• An actuator must deliver external agents via direct or indirect contact, control biochemical, bioelectrical, or biophysical parameters, and provide a safe interface with biologic materials.

Electronics Interface

• The electronics interface must match the electrical characteristics of the sensor/actuator with the computation unit, preserve the signal-to-noise ratio (SNR) of the sensor, provide a safe interface with the sensor/actuator, and provide secondary signal processing functions for the system.

Computation Unit

• The computation unit must provide a primary user interface, primary control for the overall system, data storage for the system, primary signal processing functions for the system, and maintain safe operation of the overall system.

Types of Biomedical Instrumentation Systems

• Biomedical instrumentation systems can be categorized as direct/indirect, invasive/noninvasive, contact/remote and sense/actuate.

Direct/Indirect Systems

• Direct systems measure a physiologic parameter directly, like average blood flow in an artery.
• Indirect systems measure a parameter related to the physiologic parameter of interest, for example, organ morphology determined from x-ray shadows.

Invasive/Noninvasive Systems

• Direct electrical recording of action potential in nerve fibers is an example of an invasive sensor, which requires implantable electrodes.
• An imaging system that measures blood flow dynamics in an artery (e.g., ultrasound color flow imaging) exemplifies a non-invasive sensor.

Contact/Remote Systems

• A strain gauge sensor on a muscle fiber measures deformations and forces through direct contact.
• MRI or ultrasound imaging measures internal deformations without contacting tissue, and is considered a remote method

Sense/Actuate Systems

• A sensor detects biochemical, bioelectrical, or biophysical parameters.
• An actuator delivers external agents via direct or indirect contact and/or controls biochemical, bioelectrical, or biophysical parameters.
• An automated insulin delivery pump exemplifies a direct, contact actuator.
• Noninvasive surgery using high-intensity focused ultrasound (HIFU) exemplifies a remote, noninvasive actuator.

Top Global Medical Device Companies

• Johnson & Johnson's revenue from surgical equipment (laparoscopy, ESU…), orthopedic implants, and diagnostic/therapeutic catheters is $25.1 Billion.
• Medtronic’s revenue from cardiac pacemakers, infusion/insulin pumps, defibrillators and stents is $20.2 Billion.
• GE Healthcare's revenue, including ECGs, infusion pumps, CT scanners, MRI, and ultrasound systems, is $17.6 Billion.
• Siemens Healthcare's revenue from CT scanners, MRI, ultrasound systems, laboratory diagnostics, and hematology systems is $14.5 Billion.
• Philips Healthcare's revenue includes ventilators, drug delivery systems, oximeters, X-ray machines, CT scanners, MRI, ECG, defibrillators, and monitors, and is $11.9 Billion.

Quality System (QS) and Regulations

• Medical device manufacturers are regulated globally to ensure product conformity is maintained.
• Manufacturers must establish product and process specifications and implement quality systems to ensure requirements are met.
• Objective evidence must be provided to show compliance with quality system (QS) requirements.
• The primary guidelines for medical device manufacturer QMS and related services are the ISO 13485 standards and the US FDA 21 CFR 820 regulations.

Food and Drug Administration (FDA)

• The Food and Drug Administration (FDA or USFDA) is a federal agency within the United States Department of Health and Human Services.
• The FDA's role is to protect and promote public health by controlling and supervising food safety, tobacco products, pharmaceutical drugs, vaccines, blood transfusions, medical devices, and electromagnetic radiation emitting devices (ERED).

International Organization for Standardization (ISO)

• The International Organization for Standardization (ISO) is an independent, non-governmental international organization.
• ISO publishes international standards covering technology, food safety, agriculture, and healthcare systems.
• International standards ensure quality, safety, and efficiency through world-class specifications for products, services, and systems.

FDA and ISO Compliance

• Conducting investigations according to both FDA and ISO tenets should result in trials that offer the most stringent protection for human research subjects.
• Complying with both sets of standards assures companies that resulting data is acceptable in the US and to regulatory agencies worldwide, and can be achieved through hard work and proper preparation.