Multimodal Analog Front End for Wearable Bio-Sensors

Abstract

Wearable sensors afford convenience in daily health monitoring, though many challenges in the development of such systems need to be overcome. Here, we present a low power, multimodal analog front-end (AFE) for wearable health monitoring sensors based on novel system architecture and VLSI circuit design methods. The AFE integrated circuit was designed with standard 65 nm CMOS technology. Three sensor AFEs, bio-potential, photoplethysmography (PPG) and bioelectrical impedance analyzer (BIA), were integrated on the same die with an area of 2.5 × 2.5 mm 2 . The power consumption for each AFE mode was less than 0.4 mW and did not exceed 2 mW for all three modes with a 1.2V power supply. Results from each individual AFE showed high-quality, motion-robust signals (Electrocardiogram, PPG and BIA) that correlated with those obtained from clinical grade gold-standard devices for similar applications. Such multi-functional, non-intrusive systems permit users to effortlessly self-monitor multiple clinically-relevant physiological parameters.

Fundamentals, Recent Advances, and Future Challenges in Bioimpedance Devices for Healthcare Applications

“…A research effort must be made to increase the bandwidth and the output impedance of the current source to improve the accuracy of the measurements and make the devices robust against load bioimpedance variations [112]. As the digital signal processing and wireless communications are the main sources of energy consumption in sensor devices, any progress in both the hardware and the processing algorithms will have a positive impact on increasing energy efficiency [140,353]. An alternative may be the use of comparators and timers instead of ADC to reduce the energy consumption associated with processing [354].…”

Myoelectric Interfaces and Related Applications: Current State of EMG Signal Processing–A Systematic Review

“…• Muscular activation monitoring: Gain of 600 [23], of 1000 [22], of 4000 [5], low noise and variable gain amplifier [24].…”

“…• 500 Hz, 3rd order [22] • 5-500 Hz, 2nd order [41] • 10-200 Hz [44] • 10-400 Hz [4], 3rd order [33], [4] • 10-500 Hz [30], [46], [47] • 20-250 Hz 2nd order [42] • 20-450 Hz [49] • 20-500 Hz [48], 2nd order [23] and 4th order [31], [32] • 30-300 Hz 4th order [29] • 2-750 Hz [37] • 13 works do not specify the characteristics of the filtering stage (2) Notch filters: 50 Hz and 60 Hz (depending on the frequency of the electrical network in each country).…”

A Smart Wireless Ear-Worn Device for Cardiovascular and Sweat Parameter Monitoring During Physical Exercise: Design and Performance Results

“…Our approach is to integrate multimodal sensing into a single device by making use of discrete off-the-shelf components. Another approaches use either large commercial chipsets or system-on-chip design into a custom-made smaller chip, which can integrate many functions and sensing capabilities by reconfiguring the basic analogue front-end blocks involved in the measurement of bio-potential, impedance and/or chemical analytes [22,23]. However, this latter approach has several disadvantages including longer design-to-production times and the inability to measure all modalities in simultaneous, besides requiring logical signals and reference clocks to select the desirable configuration, filter tuning and control that adds extra modulation noise originating from external complex digital circuitry.…”