Phillip M. Nadeau

Phononic band gap crystals with periodic fractal inclusions: Theoretical study using numerical analysis

A numerical study is conducted using finite difference time-domain analysis to determine the impact of periodic fractal-shaped inclusions on the frequency response of two-dimensional phononic or acoustic band gap crystals. Both solid host with solid inclusions and solid host with fluid inclusions were studied with increasing fractal order iteration or increasing fractal dimensionality for different types of fractals generated from square inclusions in a square lattice formation. Solid-fluid systems showed marked changes in frequency response including increasing multiplicity of bands compared to regular square inclusion shapes. Fractal inclusions in the solid host/fluid inclusion systems studied exhibited the ability to provide band gaps for much longer wavelengths than those of the solid host/solid inclusion systems studied. This behavior was attributed to the possibility of resonant localization effects that a fractal fluid inclusion can exhibit compared to fractal solid inclusions.A numerical study is conducted using finite difference time-domain analysis to determine the impact of periodic fractal-shaped inclusions on the frequency response of two-dimensional phononic or acoustic band gap crystals. Both solid host with solid inclusions and solid host with fluid inclusions were studied with increasing fractal order iteration or increasing fractal dimensionality for different types of fractals generated from square inclusions in a square lattice formation. Solid-fluid systems showed marked changes in frequency response including increasing multiplicity of bands compared to regular square inclusion shapes. Fractal inclusions in the solid host/fluid inclusion systems studied exhibited the ability to provide band gaps for much longer wavelengths than those of the solid host/solid inclusion systems studied. This behavior was attributed to the possibility of resonant localization effects that a fractal fluid inclusion can exhibit compared to fractal solid inclusions.

A 2.4 GHz Multi-Channel FBAR-based Transmitter With an Integrated Pulse-Shaping Power Amplifier

A 2.4 GHz TX in 65 nm CMOS defines three channels using three high-Q FBARs and supports OOK, BPSK and MSK. The oscillators have -132 dBc/Hz phase noise at 1 MHz offset, and are multiplexed to an efficient resonant buffer. Optimized for low output power ≈ - 10 dBm, a fully-integrated PA implements 7.5 dB dynamic output power range using a dynamic impedance transformation network, and is used for amplitude pulse-shaping. Peak PA efficiency is 44.4% and peak TX efficiency is 33%. The entire TX consumes 440 pJ/bit at 1 Mb/s.

An ingestible bacterial-electronic system to monitor gastrointestinal health

Using bugs in the gut to detect blood Bacteria are environmentally resilient and can be engineered to sense various biomolecules. Mimee et al. combined biosensor bacteria with a miniaturized wireless readout capsule to produce a minimally invasive device capable of in vivo biosensing in harsh, difficult-to-access environments (see the Perspective by Gibson and Burgell). The device successfully measured gastrointestinal bleeding in pigs. Science, this issue p. 915; see also p. 856 An ingestible device for sensing gut biomarkers is created by combining biological and electrical engineering approaches. Biomolecular monitoring in the gastrointestinal tract could offer rapid, precise disease detection and management but is impeded by access to the remote and complex environment. Here, we present an ingestible micro-bio-electronic device (IMBED) for in situ biomolecular detection based on environmentally resilient biosensor bacteria and miniaturized luminescence readout electronics that wirelessly communicate with an external device. As a proof of concept, we engineer heme-sensitive probiotic biosensors and demonstrate accurate diagnosis of gastrointestinal bleeding in swine. Additionally, we integrate alternative biosensors to demonstrate modularity and extensibility of the detection platform. IMBEDs enable new opportunities for gastrointestinal biomarker discovery and could transform the management and diagnosis of gastrointestinal disease.

Ultra Low-Energy Relaxation Oscillator With 230 fJ/cycle Efficiency

An ultra low-energy oscillator circuit is presented for use in picowatt level systems. The core oscillator uses an 18 transistor 3 stage architecture designed to minimize short circuit current. In addition, a transistor threshold is used to set the trip point as opposed to a voltage reference and comparator scheme, leading to overall energy savings. While operating across a wide range of low frequencies from 18 to 1000 Hz, the oscillator core consumes 110 fJ/cycle at 0.6 V. The circuit is demonstrated alongside an integrated current source to set the reference frequency. The combined system consumes a total power of 4.2 pW at 18 Hz, resulting in 230 fJ/cycle at 0.6 V.

Multi-channel 180pJ/b 2.4GHz FBAR-based receiver

A three-channel 2.4GHz OOK receiver is designed in 65nm CMOS and leverages MEMS to enable multiple sub-channels of operation within a band at a very low energy per received bit. The receive chain features an LNA/mixer architecture that efficiently multiplexes signal pathways without degrading the quality factor of the resonators. The single-balanced mixer and ultra-low power ring oscillator convert the signal to IF, where it is efficiently amplified to enable envelope detection. The receiver consumes a total of 180pJ/b from a 0.7V supply while achieving a BER=10-3 sensitivity of -67dBm at a 1Mb/s data rate.

A 440pJ/bit 1Mb/s 2.4GHz multi-channel FBAR-based TX and an integrated pulse-shaping PA

A 2.4GHz TX in 65nm CMOS defines three channels using three high-Q FBARs and supports OOK, BPSK and MSK. The oscillators have -132dBc/Hz phase noise at 1MHz offset, and are multiplexed to an efficient resonant buffer. Optimized for low output power ≈-10dBm, a fully-integrated PA implements 7.5dB dynamic output power range using a dynamic impedance transformation network, and is used for amplitude pulse-shaping. Peak PA efficiency is 44.4% and peak TX efficiency is 33%. The entire TX consumes 440pJ/bit at 1Mb/s.

21.1 Nanowatt circuit interface to whole-cell bacterial sensors

Genetically engineered, re-programmable bacterial cells are fast emerging as a platform for small molecule detection in challenging environments [1]. A key barrier to widespread deployment of autonomous bacterial sensors is the detection of low-level bioluminescence, which is typically quantified with power-hungry (watt-level) detection hardware such as Photo Multiplier Tubes (PMT). Prior work has reported successful integrated mW-level detection of bioluminescence by using PN / PIN photodiodes with OTA-based [2] and active-pixel-sensor circuits [3,4]. Our goal was to develop an even lower power readout to enable harvesting as a viable source of energy for a future batteryless autonomous biological sensor node, with applications in distributed remote environmental sensing, or in vivo biochemical sensing.

4.2 pW timer for heavily duty-cycled systems

An ultra-low energy wake-up timer suitable for heavily duty-cycled systems is presented. A prototype implemented in 0.18μm CMOS consumes 4.2pW of power for 18Hz of oscillation (0.23pJ/cycle). A dynamic 3-stage architecture, duty-cycled current-source, and low operating voltage (0.6V) enabled by a voltage boost circuit all contribute to the improved efficiency.

A Hydraulically Controlled Nonoperative Magnetic Treatment for Long Gap Esophageal Atresia

This paper describes a magnetic, non-operative device and control system designed to treat long-gap esophageal atresia (LEA). This congenital disorder occurs in approximately 100 newborn infants every year [1] and is characterized by a discontinuity in the esophagus between the mouth and stomach. Our device builds upon previous work investigating the use of internal permanent magnets to stretch the proximal and distal esophageal pouches together until anastomosis occurs. We implement a hydraulic standoff device for the proximal magnet assembly to control the distance between the two magnets independent of the esophageal gap size. The standoff allows for controllable, intermittent force between the two pouches and provides a layer of safety from runaway magnetic forces that could potentially damage delicate esophageal tissue. The proximal device comes in two variations: a convex tip for stretching the esophagus and a concave mating tip for meeting the distal end during anastomosis. An LED and phototransistor pair estimate the esophageal gap size for the duration of the procedure, and a fluid pressure sensor enables the force on the esophageal tissue to be calculated. The external control circuitry, physician interface, and pump are described that demonstrate the core functionality of the system.

Single-BAW multi-channel transmitter with low power and fast start-up time

This paper presents a multi-channel transmitter (TX) architecture that uses only a single bulk acoustic wave (BAW) resonator while covering 88 MHz of bandwidth. The proposed architecture overcomes the limited tuning range of a single BAW resonator by combining the BAW tuning range with a programmable integer-N frequency division and RF single-sideband (SSB) mixing approach. The single-BAW multi-channel TX achieves 88 MHz-wide frequency coverage with 1 MHz channels. It operates in the 2.4 GHz ISM band and the full system is demonstrated with 0 dBm output power and a fast system startup time of 2.3 μs enabled by the BAW resonator. It is implemented in 65 nm CMOS technology in a 2 mm × 2 mm area and consumes 6.4 mW from a 1.1 V supply.