arXiv subjects

Michel M. Maharbiz

Publications and source records attributed to Michel M. Maharbiz.

8 recordsLinked to original sources

arXiv2026

Integrated Circuit Architecture for Real-Time Sensing with Embedded Microbial Whole-Cell Sensors

Bacteria sense a diverse range of environmental analytes with high sensitivity and temporal resolution. Engineering and synthetic biology approaches enabled harnessing this capability through development of whole-cell biosensors that respond to specific molecules of interest. However, converting these responses into electrical signals in real time, across different environmental conditions, in miniaturized, field-deployable microelectronic devices, remains challenging. Here we present a bioelectronic platform that directly couples engineered bacteria to an integrated circuit (IC) chip through custom on-chip microelectrodes, enabling real-time, electronic readout of analyte sensing through bacterial flagellar motor dynamics. Using non-Faradaic electrochemical impedance measurements the device resolves both the direction and speed of motor rotation with a signal-to-noise ratio (SNR) of 15 dB. The IC is further integrated with a microfluidic system that enables controlled delivery and removal of analytes, nutrients and bacteria. When combined with whole-cell biosensors engineered to detect specific analytes, this work provides a miniature, portable platform for continuous monitoring in a range of liquid environments.

physics.app-ph↗

arXiv2021

An Optical Voltage Sensor Based on Piezoelectric Thin Film for Grid Applications

Continuous monitoring of voltages ranging from tens to hundreds of kV over environmental conditions, such as temperature, is of great interest in power grid applications. This is typically done via instrument transformers. These transformers, although accurate and robust to environmental conditions, are bulky and expensive, limiting their use in microgrids and distributed sensing applications. Here, we present a millimeter-sized optical voltage sensor based on piezoelectric aluminum nitride (AlN) thin film for continuous measurements of AC voltages <350kVrms (via capacitive division) that avoids the drawbacks of existing voltage-sensing transformers. This sensor operated with 110uW incident optical power from a low-cost LED achieved a resolution of 170mVrms in a 5kHz bandwidth, a measurement inaccuracy of 0.04% due to sensor nonlinearity, and a gain deviation of +/-0.2% over the temperature range of ~20-60C. The sensor has a breakdown voltage of 100V, and its lifetime can meet or exceed that of instrument transformers when operated at voltages <42Vrms. We believe that our sensor has the potential to reduce the cost of grid monitoring, providing a path towards more distributed sensing and control of the grid.

physics.app-ph↗

arXiv2020

Charge-pumping with finger capacitance in a custom electrostatic energy harvesting ASIC

We present an integrated circuit capable of scavenging energy from repetitive changes in finger touch capacitance. A finger tapping on this ASIC generates a capacitive change of approximately 770pF. These changes feed into a charge-pump circuit which stores 320pJ of energy on a 1nF storage capacitor. We present measurement results and simulations that demonstrate operation. As a proof-of-concept, we also demonstrate that the harvested energy can power a ring oscillator which outputs a series of chirps with frequencies ranging from 80Hz to 30kHz as the storage capacitor voltage charges and discharges.

physics.app-ph↗

arXiv2020

A Millimeter-scale Single Charged Particle Dosimeter for Cancer Radiotherapy

This paper presents a millimeter-scale CMOS 64$\times$64 single charged particle radiation detector system for external beam cancer radiotherapy. A 1$\times$1 $μm^2$ diode measures energy deposition by a single charged particle in the depletion region, and the array design provides a large detection area of 512$\times$512 $μm^2$. Instead of sensing the voltage drop caused by radiation, the proposed system measures the pulse width, i.e., the time it takes for the voltage to return to its baseline. This obviates the need for using power-hungry and large analog-to-digital converters. A prototype ASIC is fabricated in TSMC 65 nm LP CMOS process and consumes the average static power of 0.535 mW under 1.2 V analog and digital power supply. The functionality of the whole system is successfully verified in a clinical 67.5 MeV proton beam setting. To our' knowledge, this is the first work to demonstrate single charged particle detection for implantable in-vivo dosimetry.

physics.ins-det↗

arXiv2020

StimDust: A mm-scale implantable wireless precision neural stimulator with ultrasonic power and communication

Neural stimulation is a powerful technique for modulating physiological functions and for writing information into the nervous system as part of brain-machine interfaces. Current clinically approved neural stimulators require batteries and are many cubic centimetres in size -- typically much larger than their intended targets. We present a complete wireless neural stimulation system consisting of a 1.7 mm3 wireless, batteryless, leadless implantable stimulator (the "mote"), an ultrasonic wireless link for power and bi-directional communication, and a hand-held external transceiver. The mote consists of a piezoceramic transducer, an energy storage capacitor, and a stimulator integrated circuit (IC). The IC harvests ultrasonic power with high efficiency, decodes stimulation parameter downlink data, and generates current-controlled stimulation pulses. Stimulation parameters are time-encoded on the fly through the wireless link rather than being programmed and stored on the mote, reducing power consumption and on-chip memory requirements and enabling complex stimulation protocols with high-temporal resolution and low-latency feedback for use in closed-loop stimulation. Uplink data indicates whether the mote is currently stimulating; it is encoded by the mote via backscatter modulation and is demodulated at the external transceiver. We show that the mote operates at an acoustic intensity that is 7.8% of the FDA limit for diagnostic ultrasound and characterize the acoustic wireless link's robustness to expected real-world misalignment. We demonstrate the in vivo performance of the system with motes acutely implanted with a cuff on the sciatic nerve of anesthetized rats and show highly repeatable stimulation across a wide range of physiological responses.

q-bio.NC↗

arXiv2019

A Sub-mm$^3$ Ultrasonic Free-floating Implant for Multi-mote Neural Recording

A 0.8 mm$^3$ wireless, ultrasonically powered, free-floating neural recording implant is presented. The device is comprised only of a 0.25 mm$^2$ recording IC and a single piezoceramic resonator that is used for both power harvesting and data transmission. Uplink data transmission is performed by analog amplitude modulation of the ultrasound echo. Using a 1.78 MHz main carrier, >35 kbps/mote equivalent uplink data rate is achieved. A technique to linearize the echo amplitude modulation is introduced, resulting in <1.2\% static nonlinearity of the received signal over a $\pm$10 mV input range. The IC dissipates 37.7 $μ$W, while the neural recording front-end consumes 4 $μ$W and achieves a noise floor of 5.3 $μ$V$_{rms}$ in a 5 kHz bandwidth. This work improves sub-mm recording mote depth by >2.5x, resulting in the highest measured depth/volume ratio by $\sim$3x. Orthogonal subcarrier modulation enables simultaneous operation of multiple implants, using a single-element ultrasound external transducer. Dual-mote simultaneous power up and data transmission is demonstrated at a rate of 7 kS/s at the depth of 50 mm.

eess.SP↗

arXiv2013

Physical Principles for Scalable Neural Recording

Simultaneously measuring the activities of all neurons in a mammalian brain at millisecond resolution is a challenge beyond the limits of existing techniques in neuroscience. Entirely new approaches may be required, motivating an analysis of the fundamental physical constraints on the problem. We outline the physical principles governing brain activity mapping using optical, electrical,magnetic resonance, and molecular modalities of neural recording. Focusing on the mouse brain, we analyze the scalability of each method, concentrating on the limitations imposed by spatiotemporal resolution, energy dissipation, and volume displacement. We also study the physics of powering and communicating with microscale devices embedded in brain tissue.

q-bio.NC↗

arXiv2013

Neural Dust: An Ultrasonic, Low Power Solution for Chronic Brain-Machine Interfaces

A major hurdle in brain-machine interfaces (BMI) is the lack of an implantable neural interface system that remains viable for a lifetime. This paper explores the fundamental system design trade-offs and ultimate size, power, and bandwidth scaling limits of neural recording systems built from low-power CMOS circuitry coupled with ultrasonic power delivery and backscatter communication. In particular, we propose an ultra-miniature as well as extremely compliant system that enables massive scaling in the number of neural recordings from the brain while providing a path towards truly chronic BMI. These goals are achieved via two fundamental technology innovations: 1) thousands of 10 - 100 μm scale, free-floating, independent sensor nodes, or neural dust, that detect and report local extracellular electrophysiological data, and 2) a sub-cranial interrogator that establishes power and communication links with the neural dust.

q-bio.NC↗