Integrated Electronics for Wireless Imaging Microsystems with CMUT Arrays

Integration of transducer arrays with interface electronics in the form of single-chip CMUT-on-CMOS has emerged into the field of medical ultrasound imaging and is transforming this field. It has already been used in several commercial products such as handheld full-body imagers and it is being implemented by commercial and academic groups for Intravascular Ultrasound and Intracardiac Echocardiography. However, large attenuation of ultrasonic waves transmitted through the skull has prevented ultrasound imaging of the brain. This research is a prime step toward implantable wireless microsystems that use ultrasound to image the brain by bypassing the skull. These microsystems offer autonomous scanning (beam steering and focusing) of the brain and transferring data out of the brain for further processing and image reconstruction. The objective of the presented research is to develop building blocks of an integrated electronics architecture for CMUT based wireless ultrasound imaging systems while providing a fundamental study on interfacing CMUT arrays with their associated integrated electronics in terms of electrical power transfer and acoustic reflection which would potentially lead to more efficient and high-performance systems. A fully wireless architecture for ultrasound imaging is demonstrated for the first time. An on-chip programmable transmit (TX) beamformer enables phased array focusing and steering of ultrasound waves in the transmit mode while its on-chip bandpass noise shaping digitizer followed by an ultra-wideband (UWB) uplink transmitter minimizes the effect of path loss on the transmitted image data out of the brain. A single-chip application-specific integrated circuit (ASIC) is de- signed to realize the wireless architecture and interface with array elements, each of which includes a transceiver (TRX) front-end with a high-voltage (HV) pulser, a high-voltage T/R switch, and a low-noise amplifier (LNA). Novel design techniques are implemented in the system to enhance the performance of its building blocks. Apart from imaging capability, the implantable wireless microsystems can include a pressure sensing readout to measure intracranial pressure. To do so, a power-efficient readout for pressure sensing is presented. It uses pseudo-pseudo differential readout topology to cut down the static power consumption of the sensor for further power savings in wireless microsystems. In addition, the effect of matching and electrical termination on CMUT array elements is explored leading to new interface structures to improve bandwidth and sensitivity of CMUT arrays in different operation regions. Comprehensive analysis, modeling, and simulation methodologies are presented for further investigation.Ph.D

Modeling, Simulation and Validation of a Bio-Inspired and Self-Powered Miniature Pressure Sensing System for Monitoring Cerebral Intra Aneurysmal Pressure

Intracranial aneurysm rupture is one of the main cause for the intracranial bleeding. A brain aneurysm is an abnormal focal bulging of the arteries in the brain. As an aneurysm grows, its wall becomes thinner and weaker, which is more prone to rupture. Rupture of the intracranial aneurysm leads to releasing blood into the spaces around the brain - called a subarachnoid hemorrhage (SAH). 10 to 15% of the patients with subarachnoid hemorrhage die immediately. To prevent aneurysmal bleeding, it is essential to seclude the aneurysm from the blood circulation. This can be done with open craniotomy with microsurgical clipping and minimally invasive endovascular surgery. One of endovascular surgical technique is to place stent/flow-diverter across the neck of the aneurysm. The stent across the aneurysm reduces the flow within the aneurysm and help to form the thrombus within the aneurysm. However, approximately 3% people with the flow- diverter treatment may have delayed aneurysm bleeding after the stent placement. Short-term studies show that the stents can reduce the flow within the aneurysm but not the pressure. Currently there is no other device available to measure the intracranial intraaneurysmal pressure. This work is on designing a bio-inspired, self-powered, passively operated PVDF pressure sensor that can be deployed within the aneurysm, during flow diverting endovascular treatment that is very sensitive to small changes in pressure. The design utilizes the ear mechanics benefits by consisting of the circular vibrating membrane which vibrates based on the intraaneursymal pressure changes. This mimic the tympanic membrane part of the ear. The design continues to follow the middle ear’s mechanical advantage mechanism by incorporating the surface area increase and leverage mechanism, by the other side of the vibrating membrane been connected to three pole-links structures similar to the three bones of the middle ear to perform the middle ear’s amplification mechanism. This is followed by a composite cantilever beam structure with the sensor strips, which mimics the coiled cochlea of the inner ear in elongated form. This piezoelectric sensor strips are responsible for the passive mechanoelectrical conversion and generation of electric voltage, for the intraaneursymal pressure change application. Simulation, experiments and analysis at every level are done. Simulation and experimental result correlate and match the modeling

Roadmap on semiconductor-cell biointerfaces.

This roadmap outlines the role semiconductor-based materials play in understanding the complex biophysical dynamics at multiple length scales, as well as the design and implementation of next-generation electronic, optoelectronic, and mechanical devices for biointerfaces. The roadmap emphasizes the advantages of semiconductor building blocks in interfacing, monitoring, and manipulating the activity of biological components, and discusses the possibility of using active semiconductor-cell interfaces for discovering new signaling processes in the biological world

Hyper-Sensitive MEMS Pressure Sensor Array for Microscale Bubble Pressure Measurement

As technology is advancing, more complex, efficient, and powerful devices are being made. These powerful devices generate a lot of heat which needs to be taken out to maximize their performance. Hence, efforts are being made to improve cooling techniques for these devices. Boiling is one such technique used in the cooling of devices. The heat transfer performance in the flow boiling systems is higher than that in pool boiling systems. With a simple add-on tapered manifold over a plain surface, we can convert pool boiling to flow boiling. This study will lead to improved performance and reliability of microelectronic devices, supercomputers, server chips, etc. The forces from bubbles growing can provide a pumpless, self-sustained unidirectional flow effectively transforming pool boiling into the extremely efficient flow boiling, resulting in energy savings. MEMS pressure sensor array will be mounted at the end of tapered manifold to map the pressure field around a nucleating bubble. The thesis describes the design, fabrication, packaging, and testing of a bulk micromachined sensor array that is capable of monitoring the pressure progression of a bubble. The sensor utilizes an extremely thin 225 nm square Si3N4 diaphragm which is produced by etching away the bulk silicon with XeF2 through holes present in the diaphragm. A unique process flow was developed to achieve the diaphragm thickness in nanometers. Four polysilicon piezoresistors, mounted on the surface of the diaphragm, where the stress is maximum, are used by the sensor. The thesis also discusses the results obtained from the response of the fabricated sensor. Various attempts were made to get a voltage output in response to applied pressure. These values were acquired over a number of experiments repeated at similar experimental conditions to demonstrate the repeatability of the calibration data. The value of sensitivity, derived from the slope of the linear calibration plot of Vout (V) vs. Pressure (Pa), is 5.26 μV/Pa, which is very close to the required target hyper-sensitivity of 5 μV/Pa

Advanced sensors technology survey

This project assesses the state-of-the-art in advanced or 'smart' sensors technology for NASA Life Sciences research applications with an emphasis on those sensors with potential applications on the space station freedom (SSF). The objectives are: (1) to conduct literature reviews on relevant advanced sensor technology; (2) to interview various scientists and engineers in industry, academia, and government who are knowledgeable on this topic; (3) to provide viewpoints and opinions regarding the potential applications of this technology on the SSF; and (4) to provide summary charts of relevant technologies and centers where these technologies are being developed

Technology applications

A summary of NASA Technology Utilization programs for the period of 1 December 1971 through 31 May 1972 is presented. An abbreviated description of the overall Technology Utilization Applications Program is provided as a background for the specific applications examples. Subjects discussed are in the broad headings of: (1) cancer, (2) cardiovascular disease, (2) medical instrumentation, (4) urinary system disorders, (5) rehabilitation medicine, (6) air and water pollution, (7) housing and urban construction, (8) fire safety, (9) law enforcement and criminalistics, (10) transportation, and (11) mine safety

Integrated Circuits and Systems for Smart Sensory Applications

Connected intelligent sensing reshapes our society by empowering people with increasing new ways of mutual interactions. As integration technologies keep their scaling roadmap, the horizon of sensory applications is rapidly widening, thanks to myriad light-weight low-power or, in same cases even self-powered, smart devices with high-connectivity capabilities. CMOS integrated circuits technology is the best candidate to supply the required smartness and to pioneer these emerging sensory systems. As a result, new challenges are arising around the design of these integrated circuits and systems for sensory applications in terms of low-power edge computing, power management strategies, low-range wireless communications, integration with sensing devices. In this Special Issue recent advances in application-specific integrated circuits (ASIC) and systems for smart sensory applications in the following five emerging topics: (I) dedicated short-range communications transceivers; (II) digital smart sensors, (III) implantable neural interfaces, (IV) Power Management Strategies in wireless sensor nodes and (V) neuromorphic hardware

Mr.Wolf: An Energy-Precision Scalable Parallel Ultra Low Power SoC for IoT Edge Processing

This paper presents Mr. Wolf, a parallel ultra-low power (PULP) system on chip (SoC) featuring a hierarchical architecture with a small (12 kgates) microcontroller (MCU) class RISC-V core augmented with an autonomous IO subsystem for efficient data transfer from a wide set of peripherals. The small core can offload compute-intensive kernels to an eight-core floating-point capable of processing engine available on demand. The proposed SoC, implemented in a 40-nm LP CMOS technology, features a 108-mu W fully retentive memory (512 kB). The IO subsystem is capable of transferring up to 1.6 Gbit/s from external devices to the memory in less than 2.5 mW. The eight-core compute cluster achieves a peak performance of 850 million of 32-bit integer multiply and accumulate per second (MMAC/s) and 500 million of 32-bit floating-point multiply and accumulate per second (MFMAC/s) -1 GFlop/s-with an energy efficiency up to 15 MMAC/s/mW and 9 MFMAC/s/mW. These building blocks are supported by aggressive on-chip power conversion and management, enabling energy-proportional heterogeneous computing for always-on IoT end nodes improving performance by several orders of magnitude with respect to traditional single-core MCUs within a power envelope of 153 mW. We demonstrated the capabilities of the proposed SoC on a wide set of near-sensor processing kernels showing that Mr. Wolf can deliver performance up to 16.4 GOp/s with energy efficiency up to 274 MOp/s/mW on real-life applications, paving the way for always-on data analytics on high-bandwidth sensors at the edge of the Internet of Things

Bioresorbable Materials on the Rise: From Electronic Components and Physical Sensors to In Vivo Monitoring Systems

Over the last decade, scientists have dreamed about the development of a bioresorbable technology that exploits a new class of electrical, optical, and sensing components able to operate in physiological conditions for a prescribed time and then disappear, being made of materials that fully dissolve in vivo with biologically benign byproducts upon external stimulation. The final goal is to engineer these components into transient implantable systems that directly interact with organs, tissues, and biofluids in real-time, retrieve clinical parameters, and provide therapeutic actions tailored to the disease and patient clinical evolution, and then biodegrade without the need for device-retrieving surgery that may cause tissue lesion or infection. Here, the major results achieved in bioresorbable technology are critically reviewed, with a bottom-up approach that starts from a rational analysis of dissolution chemistry and kinetics, and biocompatibility of bioresorbable materials, then moves to in vivo performance and stability of electrical and optical bioresorbable components, and eventually focuses on the integration of such components into bioresorbable systems for clinically relevant applications. Finally, the technology readiness levels (TRLs) achieved for the different bioresorbable devices and systems are assessed, hence the open challenges are analyzed and future directions for advancing the technology are envisaged