Operation time of implantable electronic devices is largely constrained by the lifetime of batteries, which have to be replaced periodically by surgical procedures once exhausted, causing physical and mental suffering to patients and increasing healthcare costs. Besides the efficient scavenging of the mechanical energy of internal organs, this study proposes a self-powered, flexible, and one-stop implantable triboelectric active sensor (iTEAS) that can provide continuous monitoring of multiple physiological and pathological signs. As demonstrated in human-scale animals, the device can monitor heart rates, reaching an accuracy of ∼99%. Cardiac arrhythmias such as atrial fibrillation and ventricular premature contraction can be detected in real-time. Furthermore, a novel method of monitoring respiratory rates and phases is established by analyzing variations of the output peaks of the iTEAS. Blood pressure can be independently estimated and the velocity of blood flow calculated with the aid of a separate ar...

Self-Powered, One-Stop, and Multifunctional Implantable Triboelectric Active Sensor for Real-Time Biomedical Monitoring

From the first pacemaker implant in 1958, numerous engineering and medical activities for implantable medical device development have faced challenges in materials, battery power, functionality, electrical power consumption, size shrinkage, system delivery, and wireless communication. With explosive advances in scientific and engineering technology, many implantable medical devices such as the pacemaker, cochlear implant, and real-time blood pressure sensors have been developed and improved. This trend of progress in medical devices will continue because of the coming super-aged society, which will result in more consumers for the devices. The inner body is a special space filled with electrical, chemical, mechanical, and marine-salted reactions. Therefore, electrical connectivity and communication, corrosion, robustness, and hermeticity are key factors to be considered during the development stage. The main participants in the development stage are the user, the medical staff, and the engineer or technician. Thus, there are three different viewpoints in the development of implantable devices. In this review paper, considerations in the development of implantable medical devices will be presented from the viewpoint of an engineering mind.

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Development of Implantable Medical Devices: From an Engineering Perspective

Conventional content addressable memory (BCAM and TCAM) uses specialized 10T/16T bit cells that are significantly larger than 6T SRAM cells. A new BCAM/TCAM is proposed that can operate with standard push-rule 6T SRAM cells, reducing array area by 2–5× and allowing reconfiguration of the SRAM as a CAM. In this way, chip area and overall capacitance can be reduced, leading to higher energy efficiency for search operations. In addition, the configurable memory can perform bit-wise logical operations: “AND” and “NOR” on two or more words stored within the array. Thus, the configurable memory with CAM and logical function capability can be used to off-load specific computational operations to the memory, improving system performance and efficiency. Using a 6T 28 nm FDSOI SRAM bit cell, the 64×64 (4 kb) BCAM achieves 370 MHz at 1 V and consumes 0.6 fJ/search/bit. A logical operation between two 64 bit words achieves 787 MHz at 1 V.

A 28 nm Configurable Memory (TCAM/BCAM/SRAM) Using Push-Rule 6T Bit Cell Enabling Logic-in-Memory

Several conditions and diseases are linked to the elevation or depression of internal pressures from a healthy, normal range, motivating the need for chronic implantable pressure sensors. A simple implantable pressure transduction system consists of a pressure-sensing element with a method to transmit the data to an external unit. The biological environment presents a host of engineering issues that must be considered for long term monitoring. Therefore, the design of such systems must carefully consider interactions between the implanted system and the body, including biocompatibility, surgical placement, and patient comfort. Here we review research developments on implantable sensors for chronic pressure monitoring within the body, focusing on general design requirements for implantable pressure sensors as well as specifications for different medical applications. We also discuss recent efforts to address biocompatibility, efficient telemetry, and drift management, and explore emerging trends.

https://www.mdpi.com/1424-8220/14/11/20620/pdf

Chronically implanted pressure sensors: challenges and state of the field.

Ternary content addressable memories (TCAMs) represent a form of logic-in-memory and are currently widely used in routers, caches, and efficient machine learning models. From a technology prospective, researchers have begun to consider various non-volatile (NV) memory technologies to design NV TCAMs that may offer improvements with respect to figures of merit, such as energy and delay when compared to conventional CMOS designs. Among these devices, ferroelectric field effect transistors (FeFETs) stand out due to their high $ {I}_{\text {ON}}/{I}_{\text {OFF}}$ ratio, efficient voltage-driven write mechanism, low-cost, and CMOS-compatible fabrication process. We propose a 2FeFET TCAM design based on a state-of-the-art, experimentally calibrated FeFET model. We evaluate and compare our design with other TCAMs at the cell and array levels. Our results suggest that a 2FeFET TCAM requires $3.5{\times }/3200 {\times }$ less write energy than CMOS/resistive random access memory (ReRAM) TCAMs, respectively. The cell area is 13% of that of a CMOS TCAM, and is on par with ReRAM designs. The search energy-delay-product of a 2FeFET TCAM is also $4.1 {\times }/2.8 {\times }$ less than CMOS/ReRAM TCAMs, respectively.

An Ultra-Dense 2FeFET TCAM Design Based on a Multi-Domain FeFET Model

A mini-invasive system for long-term bladder urine pressure measurement system is presented. Not only is the design cost reduced, but also the reliability is enhanced by using a 1-atm canceling sensing instrumentation amplifier (IA). Because the urine pressure inside the bladder does not vary drastically, both the sleeping and working modes are required in order to save the battery power for long-term observation. The IA amplifies the signal sensed by the pressure sensor, which is then fed into the following analog-to-digital converter. Owing to the intrinsic 1-atm pressure existing inside the bladder, the IA must be able to cancel such a pressure from the signal picked up by the pressure sensor to keep the required linearity and the resolution for pressure measurement of the bladder urine. The pressure range of the proposed system is found out to be 14.7~19.7 Psi, which covers the range of all of the known unusual bladder syndromes or complications.

A Mini-Invasive Long-Term Bladder Urine Pressure Measurement ASIC and System

A low-power content-addressable memory (CAM) using a differential match line (ML) sense amplifier is proposed in this work The proposed self-disabled sensing technique can choke the charge current fed into the ML right after the matching comparison is generated Instead of using typical nor/ nand-type CAM cells with the single-ended ML, the proposed novel nand CAM cell with the differential ML design can boost the speed of comparison without sacrificing power consumption In addition, the 9-T CAM cell with disabled read-out circuit provides the complete write, read, and comparison functions to refresh the data and verify its correctness before searching The CAM with the proposed technique is implemented on silicon to justify the performance by using a standard 013-?m complementary metal-oxide-semiconductor process The energy consumption of the searching process is 1872 fJ/bit/search

A Self-Disabled Sensing Technique for Content-Addressable Memories

A miniature amplitude-shift-keying (ASK) demodulator without any passive elements, i.e., R or C, for low-frequency applications is presented in the paper. The noise margin of the envelope detector in the proposed ASK demodulator is enlarged such that any Schmitt trigger or current limiting resistor is no longer needed. It results in the number of transistors required for the ASK demodulator circuit is reduced to 12, while the area is merely 0.003025 mm2 using 0.35-mum 2P4M CMOS process. The power consumption is found to be 1.01 mW by physical measurement on silicon. The data rate is measured to be 250 kbps for 2-MHz carrier frequency and 27% modulation index.

All-MOS ASK Demodulator for Low-Frequency Applications

This paper presents an architecture as well as circuit implementation of a ZigBee modulator/demodulator in the transceiver for personal area network, which is compliant with the physical layer of IEEE standard 802.15.4. A test prototype has been designed and fabricated using 0.18-mum single-poly six-metal CMOS process with core area of 0.16 mm2 . The measurement results show that packet error rate (PER) is less than 1% given SNR = 5 dB. The total power consumption is merely 251 muW at a 2.4-MHz system clock.

ZigBee 868/915-MHz Modulator/Demodulator for Wireless Personal Area Network

A high speed and low power 8-bit carry-lookahead adder using two-phase modified dual-threshold voltage (dual-Vt) domino logic blocks which are arranged in a programmable logical array-like design style with pipelining is presented. The modified domino logic circuits employ dual-transistors and reversed bulk-source biases for reducing subthreshold leakage current when advanced deep submicrometer process is used. Moreover, an nMOS transistor is inserted in the discharging path of the output inverter such that the modified domino logic can be properly applied in a pipeline structure to reduce the power consumption. The addition of two 8-bit binary operands is executed in two cycles. Not only is it proven to be also suitable for long adders, the dynamic power consumption is also drastically reduced by more than 10% by the measurement results on silicon.

Chi-Chun Huang

Papers

A Mini-Invasive Long-Term Bladder Urine Pressure Measurement ASIC and System

A Self-Disabled Sensing Technique for Content-Addressable Memories

All-MOS ASK Demodulator for Low-Frequency Applications

ZigBee 868/915-MHz Modulator/Demodulator for Wireless Personal Area Network

A Low Power High-Speed 8-Bit Pipelining CLA Design Using Dual-Threshold Voltage Domino Logic