Patrick P. Mercier

A wearable chemical–electrophysiological hybrid biosensing system for real-time health and fitness monitoring

Flexible, wearable sensing devices can yield important information about the underlying physiology of a human subject for applications in real-time health and fitness monitoring. Despite significant progress in the fabrication of flexible biosensors that naturally comply with the epidermis, most designs measure only a small number of physical or electrophysiological parameters, and neglect the rich chemical information available from biomarkers. Here, we introduce a skin-worn wearable hybrid sensing system that offers simultaneous real-time monitoring of a biochemical (lactate) and an electrophysiological signal (electrocardiogram), for more comprehensive fitness monitoring than from physical or electrophysiological sensors alone. The two sensing modalities, comprising a three-electrode amperometric lactate biosensor and a bipolar electrocardiogram sensor, are co-fabricated on a flexible substrate and mounted on the skin. Human experiments reveal that physiochemistry and electrophysiology can be measured simultaneously with negligible cross-talk, enabling a new class of hybrid sensing devices.

A pulsed UWB receiver SoC for insect motion control

For decades, scientists and engineers have been fascinated by cybernetic organisms, or cyborgs, that fuse artificial and natural systems. Cyborgs enable harnessing biological systems that have been honed by evolutionary forces over millennia to achieve astounding feats. Male moths can detect a single pheromone molecule, a sensitivity of roughly 10−21 grams. Thus, cyborgs can perform tasks at scales and efficiencies that would ordinarily seem incomprehensible. Semiconductor technology is central to realizing this vision offering powerful processing and communication capabilities, as well as low weight, small size, and deterministic control. An emerging cyborg application is moth flight control, where electronics and MEMS devices are placed on and within a moth to control flight direction. To receive commands on the moth, a lightweight, low power and low volume RX is required. This paper presents a pulsed ultrawideband (UWB) RX SoC designed for the stringent weight, volume and power constraints of the cyborg moth system.

energy extraction from the biologic battery in the inner ear

Endocochlear potential (EP) is a battery-like electrochemical gradient found in and actively maintained by the inner ear. Here we demonstrate that the mammalian EP can be used as a power source for electronic devices. We achieved this by designing an anatomically sized, ultra-low quiescent-power energy harvester chip integrated with a wireless sensor capable of monitoring the EP itself. Although other forms of in vivo energy harvesting have been described in lower organisms, and thermoelectric, piezoelectric and biofuel devices are promising for mammalian applications, there have been few, if any, in vivo demonstrations in the vicinity of the ear, eye and brain. In this work, the chip extracted a minimum of 1.12 nW from the EP of a guinea pig for up to 5 h, enabling a 2.4 GHz radio to transmit measurement of the EP every 40–360 s. With future optimization of electrode design, we envision using the biologic battery in the inner ear to power chemical and molecular sensors, or drug-delivery actuators for diagnosis and therapy of hearing loss and other disorders.

An Energy-Efficient All-Digital UWB Transmitter Employing Dual Capacitively-Coupled Pulse-Shaping Drivers

This paper presents an all-digital, non-coherent, pulsed-UWB transmitter. By exploiting relaxed center frequency tolerances in non-coherent wideband communication, the transmitter synthesizes UWB pulses from an energy-efficient, single-ended digital ring oscillator. Dual capacitively coupled digital power amplifiers (PAs) are used in tandem to attenuate low frequency content typically associated with single-ended digital circuits driving single-ended antennas. Furthermore, four level digital pulse shaping is employed to attenuate RF sidelobes, resulting in FCC compliant operation in the 3.5, 4.0, and 4.5 GHz IEEE 802.15.4a bands without the use of any off-chip filters or large passive components. The transmitter is fabricated in a 90 nm CMOS process and occupies a core area of 0.07 mm2 . The entirely digital architecture consumes zero static bias current, resulting in an energy efficiency of 17.5 pJ/pulse at data rates up to 15.6 Mb/s.

Low-Power Impulse UWB Architectures and Circuits

Ultra-wide-band (UWB) communication has a variety of applications ranging from wireless USB to radio frequency (RF) identification tags. For many of these applications, energy is critical due to the fact that the radios are situated on battery-operated or even batteryless devices. Two custom low-power impulse UWB systems are presented in this paper that address high- and low-data-rate applications. Both systems utilize energy-efficient architectures and circuits. The high-rate system leverages parallelism to enable the use of energy-efficient architectures and aggressive voltage scaling down to 0.4 V while maintaining a rate of 100 Mb/s. The low-rate system has an all digital transmitter architecture, 0.65 and 0.5 V radio-frequency (RF) and analog circuits in the receiver, and no RF local oscillators, allowing the chipset to power on in 2 ns for highly duty-cycled operation.

Wearable salivary uric acid mouthguard biosensor with integrated wireless electronics

This article demonstrates an instrumented mouthguard capable of non-invasively monitoring salivary uric acid (SUA) levels. The enzyme (uricase)-modified screen printed electrode system has been integrated onto a mouthguard platform along with anatomically-miniaturized instrumentation electronics featuring a potentiostat, microcontroller, and a Bluetooth Low Energy (BLE) transceiver. Unlike RFID-based biosensing systems, which require large proximal power sources, the developed platform enables real-time wireless transmission of the sensed information to standard smartphones, laptops, and other consumer electronics for on-demand processing, diagnostics, or storage. The mouthguard biosensor system offers high sensitivity, selectivity, and stability towards uric acid detection in human saliva, covering the concentration ranges for both healthy people and hyperuricemia patients. The new wireless mouthguard biosensor system is able to monitor SUA level in real-time and continuous fashion, and can be readily expanded to an array of sensors for different analytes to enable an attractive wearable monitoring system for diverse health and fitness applications.

23.2 A 1.1nW energy harvesting system with 544pW quiescent power for next-generation implants

A wireless sensor that is powered from the endocochlear potential (EP), a 70-to-100mV bio-potential inside the mammalian ear, has been demonstrated in [1]. Due to the anatomical size and physiological constraints inside the ear, a maximum of 1.1 to 6.25nW can be extracted from the EP. The nanowatt power budget of the sensor gives rise to unique challenges with power conversion efficiency and quiescent current reduction in the power management unit (PMU). While [1] presents the system aspects of the biomedical harvesting including the biologic interface and system measurements, this work presents the details of the nanowatt PMU required to power the electronics. More specifically, it focuses on the low-power circuit design techniques needed to realize a nW power converter that is applicable to a broad spectrum of emerging biomedical applications with ultra-low energy-harvesting sources.

Wearable textile biofuel cells for powering electronics

The fabrication and performance of a wearable biofuel cell printed directly onto textile substrates are reported. The textile biofuel cell utilizes physiologically produced sweat lactate as the fuel to generate electrical energy, producing up to 100 μW cm−2 at 0.34 V during in vitro experimentation, even after repeated bending stress. Furthermore, the wearable and flexible biofuel cell can be easily integrated with a portable energy storage device for on-demand powering of wearable electronics. To validate energy harvesting, the biofuel cell is integrated into a headband and a wristband, and with the help of an on-board DC/DC converter, extracts energy from perspiring human subjects for direct powering of an LED or a digital watch. Convenient incorporation and removal from a variety of garments are achieved by printing the biofuel cell on a detachable care label. Such textile-based non-invasive biofuel cells can be expected to serve in the future as the power unit for wearable electronics and biomedical devices.

Energy Efficient Pulsed-UWB CMOS Circuits and Systems

A custom UWB transceiver chipset is presented that communicates in three 550 MHz-wide channels in the 3.1 to 5 GHz band by using pulse position modulation (PPM). The transmitter uses an all-digital architecture and calibration technique to synthesize pulses with programmable width and center frequency. No analog bias currents or RF oscillators are required in the transmitter. The receiver performs channel-selection filtering, energy detection, and bit-slicing. The receiver circuits operate at 0.65 V and 0.5 V, and can turn on in 2 ns for duty-cycled operation. The two chips are fabricated in a 90 nm CMOS process, and achieve a combined 2.5 nJ/bit at a data rate of 16.7 Mb/s.

Ultra-low-power UWB for sensor network applications

Long distance, low data-rate UWB communication for sensor network applications requires a highly energy efficient transceiver combined with circuit and system-level optimizations to maximize range. A custom pulsed-UWB transceiver chipset in 90 nm CMOS is presented that targets these aggressive specifications. The transceiver efficiently communicates at data rates from 0-to-16.7 Mbps in three 550 MHz-wide channels in the 3.1 to 5 GHz band by using pulse position modulation (PPM). The transmitter uses an all-digital architecture and calibration technique to synthesize pulses with programmable width and center frequency. The non-coherent receiver operates at 0.65 V and performs channel selection Altering, energy detection, and bit-slicing. As FCC regulations limit the maximum transmit power of UWB communication, a run-length limiting technique is presented to reduce energy requirements when maximizing range at low data rates.