Looking a little more deeply, Figure 2 shows a SEM cross-section of the ADS1298. A robust and high yielding 0.35um, 4-layer Aluminum Bi-CMOS process has been used. The Bi-CMOS process and low noise bipolar amplifiers contribute to the low power consumption and noise performance.
Figure 2: SEM cross-section of the TI ADS1298 chip showing use of the well-established, high yield and reliable 4-layer Al 0.35-micron process.
The ADS129x series is featured in the Sotera Wireless' ViSi Mobile Patient Monitor that received FDA clearance in April 2012. This first generation system from Sotera Wireless is a hospital-based continuous vital signs monitoring system. The system is small, worn on the wrist and includes three sensors:
• Optical thumb sensor for measuring pulse rate and SpO2
• Chest sensor for measuring ECG/HR, respiration, and skin temperature
• Cuff module for single-inflation or automatic NIBP monitoring.
Figre 3: Sotera's ViSi Mobile System takes advantage of the ADS1298's small size and lower power consumption in its wrist-worn monitor. (Image Credit: Sotera Wireless)
The small size improves patient comfort and mobility. The system's low cost brings the benefits of continuous monitoring to a wider range of patients. Under development, and not yet cleared by the FDA, are versions that include additional functionality such as wireless connectivity. Sotera Wireless CTO, Jim Moon, explains the importance of the ADS129x family to their device development: "TI's ADS1298R analog front end for patient monitoring provided the means to make the ViSi Mobile Patient Monitor possible. The reduction in size and power consumption that it delivers is unparalleled."
The medical electronics design sector shares many engineering challenges with consumer electronics, with the added requirement of very high reliability. Devices such as TI's ADS129x family demonstrate that these challenges are being met and that this sector is very much worth watching for technical innovation.
Treena Grevatt is product marketing manager at UBM TechInsights, a division of UBM LLC, the publisher of EE Times.