Common Design Procedures for Medical Instruments

Common Design Procedures for Medical Instruments

Medical Instruments – From Texas Instruments

These medical instruments are Industries standard design and process controls. It may very useful to engineering students who can study the medical electronics.

Medical Instruments such as blood glucose meter, digital blood pressure meter, blood gas meter, digital pulse/heart rate monitor or even a digital thermometer leverage five system level blocks that are common to each.

Block Diagram for common Portable Medical Equipments

Some Medical Instruments

Blood Glucose Meter
Digital Blood Pressure Meter
Blood Gas Meter
Digital pulse/heart Rate Monitor

Portable Medical Applications:

Whether developing a blood glucose meter, digital blood pressure meter, blood gas meter, digital pulse/heart rate monitor or even a digital thermometer there are five system level blocks that are common to each one:

Five Common Blocks for Medical Applications

Power/Battery Management,
Control and Data processing,
Amplification and A/D Conversion of the sensor input,
Some type of display and the sensor element(s) itself.

In general these are all microcontroller controlled handheld devices that operate on battery and take measurements using various bio-sensors.
Obviously, the actual implementation topology of these blocks will differ greatly with the sensing, processing and information display demands of the meter type and feature set.

Key design considerations are ultra-low power consumption and high efficiency driven by the need for extended battery life, and high precision with a fast response time driven by the users need to quickly knows the status of their health.

Additional requirements may drive needs for additional memory to allow for historical profiling, cabled or wireless interfaces for data upload to a computer at home of in the doctors office or even for access to the sensor, and possibly audio feedback for simple good/not good indication or more complex step by step utilization instructions.

Adding these features without increasing power consumption is a significant challenge.

Texas Instruments portfolio of Microcontrollers, Digital Signal
Processors (DSPs), Instrumentation and Buffer Amplifiers, Power and Battery Management, Audio Amplifiers, and both wired and wireless interface devices provides the ideal tool box for Portable medical applications.

Electronic Devices

Analog to Digital Converters

SP430x4xx - Flash/ROM LCD

Doctor less DC/DC Regulators (Charge Pumps)

Lighting and Display Solutions

The common core subsystems are:

Analog Front-End/Sensor Interface - Bio-sensor and ambient temperature input are amplified and then digitized by the A/D converter.

LCD/LED/Keypad - Data display and entry.

Microcontroller

Executes glucose measuring processes and controls interface with memory and peripheral devices.
It also executes speech-synthesizer software to output voice instructions for the blood-glucose monitoring procedure.

Audio Amplifier

The audio amplifier amplifies the audio output coming either from a PWM circuit or from the DAC.
The PWM generates beeping sounds to notify when the measuring results are available. The DAC output voice instructions from the speech-synthesizer software.

Memory/Peripheral Devices - Measurements results are stored in EEPROM or FLASH memory as a data log that can be uploaded to a PC via USB interface.

Power Management and Conversion - converts the input battery power to run various functional blocks.