Medical Design Briefs - May 2024 - 19

Fig. 3 - Hardware schematic for a customized glucometer using GreenPAK.
power to extend their operating period. In addition, portable
medical devices must be power efficient. The GreenPAK
family is very efficient in terms of power consumption, with
typical idle current consumption in the order of microamps,
and these ICs are available in small TQFN and MSTQFN
packages. These factors make them suitable for such types of
applications.
* Compatibility: because input and outputs of the ICs are digital
or analog signals, including standardized protocols such as
I2
C or SPI, they are fully compatible with other components
that are usually used in these applications.
Medical Applications
Vital Sign Monitoring System. The development and implementation
of a vital sign monitoring system is based on measuring
heart rate, temperature, blood pressure, and breathing rate. To do
so, different sensors must be used, and analog signal conditioning
must be implemented. Based on the capabilities described above,
using both GreenPAK and AnalogPAK is a very interesting alternative
for processing these signal types. This case also illustrates how
they can be combined, taking advantage of their flexibility, programmability,
and analog precision (see Figures 1 and 2).
More details about an aspect of this application can be
found in the application notes " Analog Front End for Heart
Rate Monitor " and " Analog Front End for Electrocardiogram
Monitor " at the end of this article. They show how the heart
Medical Design Briefs, May 2024
rate can be measured, including different techniques to obtain
the signal and an IC configuration to implement the analog
front end.
For temperature and breathing rate, the analog input capabilities
such as the ADCs can be applied to interface with sensors
to measure temperature, and digital inputs and DFFs with
timing blocks can be used for breathing rate measurement.
In the case of blood pressure sensing, programmable digital
logic can be used to implement control algorithms. This can
include managing inflation and deflation of the cuff, and the
sequence for reading sensor values and determining blood
pressure levels. The analog signals from the sensors can be conditioned
and acquired with the OPAMPs and processed with
analog comparators.
Glucose Sensor and Monitor. In this case, a glucose sensor
and monitor device is analyzed. This application is usually
designed as a portable device, powered by a rechargeable
battery, playing an important role in controlling diabetic patient's
health. As a consequence, high efficiency in energy
consumption is required. In this case, AnalogPAK can be
used for both signal conditioning and measurement as well
as signal processing and user interface. It has a highly efficient
IC in terms of power consumption, both in processing
state and in idle state (see Figure 3).
More details about this application can be found in the application
note " Customized Glucometer using GreenPAK " at the
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Medical Design Briefs - May 2024

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