Implantable Chip Research Articles

Biodegradable Oxide Neuromorphic Transistors for Neuromorphic Computing and Anxiety Disorder Emulation.

Brain-inspired neuromorphic computing and portable intelligent electronic products have received increasing attention. In the present work, nanocellulose-gated indium tin oxide neuromorphic transistors are fabricated. The device exhibits good electrical performance. Short-term synaptic plasticities were mimicked, including excitatory postsynaptic current, paired-pulse facilitation, and dynamic high-pass synaptic filtering. Interestingly, an effective linear synaptic weight updating strategy was adopted, resulting in an excellent recognition accuracy of ∼92.93% for the Modified National Institute of Standard and Technology database adopting a two-layer multilayer perceptron neural network. Moreover, with unique interfacial protonic coupling, anxiety disorder behavior was conceptually emulated, exhibiting "neurosensitization", "primary and secondary fear", and "fear-adrenaline secretion-exacerbated fear". Finally, the neuromorphic transistors could be dissolved in water, demonstrating potential in "green" electronics. These findings indicate that the proposed oxide neuromorphic transistors would have potential as implantable chips for nerve health diagnosis, neural prostheses, and brain-machine interfaces.

ReplaceNet: real-time replacement of a biological neural circuit with a hardware-assisted spiking neural network.

Recent developments in artificial neural networks and their learning algorithms have enabled new research directions in computer vision, language modeling, and neuroscience. Among various neural network algorithms, spiking neural networks (SNNs) are well-suited for understanding the behavior of biological neural circuits. In this work, we propose to guide the training of a sparse SNN in order to replace a sub-region of a cultured hippocampal network with limited hardware resources. To verify our approach with a realistic experimental setup, we record spikes of cultured hippocampal neurons with a microelectrode array (in vitro). The main focus of this work is to dynamically cut unimportant synapses during SNN training on the fly so that the model can be realized on resource-constrained hardware, e.g., implantable devices. To do so, we adopt a simple STDP learning rule to easily select important synapses that impact the quality of spike timing learning. By combining the STDP rule with online supervised learning, we can precisely predict the spike pattern of the cultured network in real-time. The reduction in the model complexity, i.e., the reduced number of connections, significantly reduces the required hardware resources, which is crucial in developing an implantable chip for the treatment of neurological disorders. In addition to the new learning algorithm, we prototype a sparse SNN hardware on a small FPGA with pipelined execution and parallel computing to verify the possibility of real-time replacement. As a result, we can replace a sub-region of the biological neural circuit within 22 μs using 2.5 × fewer hardware resources, i.e., by allowing 80% sparsity in the SNN model, compared to the fully-connected SNN model. With energy-efficient algorithms and hardware, this work presents an essential step toward real-time neuroprosthetic computation.

CMOS Perceptron for Vesicle Fusion Classification

Edge computing (processing data close to its source) is one of the fastest developing areas of modern electronics and hardware information technology. This paper presents the implementation process of an analog CMOS preprocessor for use in a distributed environment for processing medical data close to the source. The task of the circuit is to analyze signals of vesicle fusion, which is the basis of life processes in multicellular organisms. The functionality of the preprocessor is based on a classifier of full and partial fusions. The preprocessor is dedicated to operate in amperometric systems, and the analyzed signals are data from carbon nanotube electrodes. The accuracy of the classifier is at the level of 93.67%. The implementation was performed in the 65 nm CMOS technology with a 0.3 V power supply. The circuit operates in the weak-inversion mode and is dedicated to be powered by thermal cells of the human energy harvesting class. The maximum power consumption of the circuit equals 416 nW, which makes it possible to use it as an implantable chip. The results can be used, among others, in the diagnosis of precancerous conditions.

A Systematic Review of Bio-Cyber Interface Technologies and Security Issues for Internet of Bio-Nano Things

Advances in synthetic biology and nanotechnology have contributed to the design of tools that can be used to control, reuse, modify, and re-engineer cells' structure, as well as enabling engineers to effectively use biological cells as programmable substrates to realize Bio-Nano Things (biological embedded computing devices). Bio-NanoThings are generally tiny, non-intrusive, and concealable devices that can be used for in-vivo applications such as intra-body sensing and actuation networks, where the use of artificial devices can be detrimental. Such (nano-scale) devices can be used in various healthcare settings such as continuous health monitoring, targeted drug delivery, and nano-surgeries. These services can also be grouped to form a collaborative network (i.e., nanonetwork), whose performance can potentially be improved when connected to higher bandwidth external networks such as the Internet, say via 5G. However, to realize the IoBNT paradigm, it is also important to seamlessly connect the biological environment with the technological landscape by having a dynamic interface design to convert biochemical signals from the human body into an equivalent electromagnetic signal (and vice versa). This, unfortunately, risks the exposure of internal biological mechanisms to cyber-based sensing and medical actuation, with potential security and privacy implications. This paper comprehensively reviews bio-cyber interface for IoBNT architecture, focusing on bio-cyber interfacing options for IoBNT like biologically inspired bio-electronic devices, RFID enabled implantable chips, and electronic tattoos. This study also identifies known and potential security and privacy vulnerabilities and mitigation strategies for consideration in future IoBNT designs and implementations.

CMOS 256-Pixel/480-Pixel Photovoltaic-Powered Subretinal Prosthetic Chips With Wide Image Dynamic Range and Bi/Four-Directional Sharing Electrodes and Their Ex Vivo Experimental Validations With Mice

CMOS photovoltaic-powered 256-pixel/480-pixel implantable chips with a wide image dynamic range and shared electrodes are proposed and fabricated in CIS technology for subretinal prostheses. The infra-red (IR) light is incident only on photovoltaic cells of the chip whereas the visible light is mainly incident on pixels. The proposed adaptive background cancellation circuit (ABCC) is adopted to increase the image dynamic range so that the subretinal chips can adapt for different surrounding illuminances. A two-dimensional equivalent electrode model for electric crosstalk simulation is proposed to analyze the crosstalk charges and enable the stimulation pattern design with minimum crosstalk for both chips. Moreover, the bi-directional sharing electrodes (BDSEs) are used in the 256-pixel chip to increase electrode size under the same chip area and boost the stimulation charges to 11.4 nC. The four-directional sharing electrodes (FDSEs) are used to share the electrodes in both vertical and horizontal directions and achieve 480 pixels with nearly the same electrode size under the same pixel array area. The maximum stimulation charge is 9.8 nC. The dynamic range of image light is increased to 31.65 dB (24.9 dB) in the fabricated 256-pixel (480-pixel) chip. The functions of the chip have been successfully validated by both electrical measurement and ex vivo patch clamp experiments with the retinas of mice.

Design Consideration for Developing Bio-potential Instrumentation Amplifier Intended for Bionic Eye.

According to the Survey of WHO [World Health Organization] ,a people of about 285 million are visually impaired, 39 million are blind and 246 million are having low vision. Blindness is a serious ailment that makes people to suffer a lot. It occurs because of the eye related disorders like Retinitis Pigmentosa[RP], Age-Related Macular Degeneration[AMRD] and Glaucoma, resulting to lead an uncomfortable life style. Recent developments of the Biomedical Engineering field lead to the development of artificial human eye-Bionic eye analogous to natural eye. Bionic eye is a complex system which is integrated with many sub systems such as CCD camera, video processing unit, implantable chip , radio transmitter and receiver. The implanted artificial retina helps the patients of RP and AMRD regains the vision. Apart from this there exist limitations because of electrode count and noise levels. For better optimization to reduce noise levels of bio-potential signals an instrumentation amplifier is used. In this paper different Instrumentation amplifier are discussed.

Design Consideration for Developing Bio-potential Instrumentation Amplifier Intended for Bionic Eye.

According to the Survey of WHO [World Health Organization] ,a people of about 285 million are visually impaired, 39 million are blind and 246 million are having low vision. Blindness is a serious ailment that makes people to suffer a lot. It occurs because of the eye related disorders like Retinitis Pigmentosa[RP], Age-Related Macular Degeneration[AMRD] and Glaucoma, resulting to lead an uncomfortable life style. Recent developments of the Biomedical Engineering field lead to the development of artificial human eye-Bionic eye analogous to natural eye. Bionic eye is a complex system which is integrated with many sub systems such as CCD camera, video processing unit, implantable chip , radio transmitter and receiver. The implanted artificial retina helps the patients of RP and AMRD regains the vision. Apart from this there exist limitations because of electrode count and noise levels. For better optimization to reduce noise levels of bio-potential signals an instrumentation amplifier is used. In this paper different Instrumentation amplifier are discussed.

Implantable Devices with Reconfigurable Biosensing Analog Front End

This paper, have a tendency to develop a reconfigurable analog front end for wireless body sensing element nodes and implantable devices with reduced size. By converting voltage in to current the effort to achieve the area efficiency is taken. Because these are bio implantable chips if the numbers of transistors are reduced it will reduce lots of power and area, the circuit operation is also quick. In the proposed system, narrow swing current mirror circuit is used in the low pass filter region. By using the current mirror the same input current can be obtained at the output. At the same time the area of the chip used in the devices gets reduced. The active space of the chip is 157µm2.

Improved Charge Pump Design and Ex Vivo Experimental Validation of CMOS 256-Pixel Photovoltaic-Powered Subretinal Prosthetic Chip.

An improved design of CMOS 256-pixel photovoltaic-powered implantable chip for subretinal prostheses is presented. In the proposed subretinal chip, a high-efficiency fully-integrated 4× charge pump is designed and integrated with on-chip photovoltaic (PV) cells and a 256-pixel array with active pixel sensors (APS) for image light sensing, biphasic constant current stimulators, and electrodes. Thus the PV voltage generated by infrared (IR) light can be boosted to above 1V so that the charge injection is increased. The proposed chip adopts the 32-phase divisional power supply scheme (DPSS) to reduce the required supply current and thus the required area of the PV cells. The proposed chip is designed and fabricated in 180-nm CMOS image sensor (CIS) technology and post-processed with biocompatible IrOx electrodes and silicone packaging. From the electrical measurement results, the measured stimulation frequency is 28.3 Hz under the equivalent electrode impedance load. The measured maximum output stimulation current is 7.1 μA and the amount of injected charges per pixel is 7.36 nC under image light intensity of 3200 lux and IR light intensity of 100 mW/cm2. The function of the proposed chip has been further validated successfully with the ex vivo experimental results by recording the electrophysiological responses of retinal ganglion cells (RGCs) of retinas from retinal degeneration (rd1) mice with a multi-electrode array (MEA). The measured average threshold injected charge is about 3.97 nC which is consistent with that obtained from the patch clamp recording on retinas from wild type (C57BL/6) mice with a single electrode pair.

Analysis of wave propagation for wireless implantable body area network application

The enhancement technologies of wireless body area network improved the health monitoring system. Previous work have been designed the implantable chip printed antenna at 4.8 GHz. This paper is continuing the investigation where the antenna wave propagation in term of attenuation and polarization were studied. The antenna is implanted in human hand voxel model from CST Microwave Studio Software. The performances of the antenna are evaluated in term of return loss, gain and efficiency. Results show that the rate attenuation for the propagation is approximately 0.16 dB up to 0.42 dB. All the results will be guidelines in designing implantable antennas in futures.

Numerical Investigation of a Chip Printed Antenna Performances for Wireless Implantable Body Area Network Applications

Recently, wireless implantable body area network (WiBAN) system become an active area of research due to their various applications such as healthcare, support systems for specialized occupations and personal communications. Biomedical sensors networks mounted in the human body have drawn greater attention for health care monitoring systems. The implantable chip printed antenna for WiBAN applications is designed and the antenna performances is investigated in term of gain, efficiency, return loss, operating bandwidth and radiation pattern at different environments. This paper is presents the performances of implantable chip printed antenna in selected part of human body (hand, chest, leg, heart and skull). The numerical investigation is done by using human voxel model in built in the CST Microwave Studio Software. Results proved that the chip printed antenna is suitable to implant in the human hand model. The human hand model has less complex structure as it consists of skin, fat, muscle, blood and bone. Moreover, the antenna is implanted under the skin. Therefore the signal propagation path length to the base station at free space environment is considerably short. The antenna’s gain, efficiency and Specific Absorption Rate (SAR) are - 13.62dBi, 1.50 % and 0.12 W/kg respectively; which confirms the safety of the antenna usage. The results of the investigations can be used as guidance while designing chip implantable antenna in future.

An Inductive Power and Data Telemetry Subsystem With Fast Transient Low Dropout Regulator for Biomedical Implants.

This paper presents a capacitorless low-dropout (LDO) regulator with fast transient response and data reverse telemetry circuit for fully implantable wireless transmission applications. We propose a novel hybrid feedback structure using high-frequency compensation technology to achieve a rapid transient response for the LDO regulator. To reduce the size of the implant and transmit neural recordings through the same coil without interfering with power transmission, the load-shift-key (LSK) modulation technique is adopted for back data telemetry. The proposed implantable chip, fabricated using commercial 0.18 μm complementary metal oxide semiconductor technology, yielded an output power of 15 mW. Under 1.15 V operation voltage, the maximum overshoot and undershoot voltages were less than 45 mV and 55 mV, respectively, for a 15 mA full-load current whose rising and falling time were less than 100 ns. The proposed LSK transceiver uses a digitized demodulator to improve bandwidth efficiency for low carrier frequency operation.

Wireless implantable chip with integrated nitinol-based pump for radio-controlled local drug delivery.

We demonstrate an active, implantable drug delivery device embedded with a microfluidic pump that is driven by a radio-controlled actuator for temporal drug delivery. The polyimide-packaged 10 × 10 × 2 mm(3) chip contains a micromachined pump chamber and check valves of Parylene C to force the release of the drug from a 76 μL reservoir by wirelessly activating the actuator using external radio-frequency (RF) electromagnetic fields. The rectangular-shaped spiral-coil actuator based on nitinol, a biocompatible shape-memory alloy, is developed to perform cantilever-like actuation for pumping operation. The nitinol-coil actuator itself forms a passive 185 MHz resonant circuit that serves as a self-heat source activated via RF power transfer to enable frequency-selective actuation and pumping. Experimental wireless operation of fabricated prototypes shows successful release of test agents from the devices placed in liquid and excited by radiating tuned RF fields with an output power of 1.1 W. These tests reveal a single release volume of 219 nL, suggesting a device's capacity of ~350 individual ejections of drug from its reservoir. The thermal behavior of the activated device is also reported in detail. This proof-of-concept prototype validates the effectiveness of wireless RF pumping for fully controlled, long-lasting drug delivery, a key step towards enabling patient-tailored, targeted local drug delivery through highly miniaturized implants.

A remotely powered implantable biomedical system with location detector.

An universal remote powering and communication system is presented for the implantable medical devices. The system be interfaced with different sensors or actuators. A mobile external unit controls the operation of the implantable chip and reads the sensor's data. A locator system is proposed to align the mobile unit with the implant unit for the efficient magnetic power transfer. The location of the implant is detected with 6 mm resolution from the rectified voltage level at the implanted side. The rectified voltage level is fedback to the mobile unit to adjust the magnetic field strength and maximize the efficiency of the remote powering system. The sensor's data are transmitted by using a free running oscillator modulated with on-off key scheme. To tolerate large data carrier drifts, a custom designed receiver is implemented for the mobile unit. The circuits have been fabricated in 0.18 um CMOS technology. The remote powering link is optimized to deliver power at 13.56 MHz. On chip voltage regulator creates 1.8 V from a 0.9 V reference voltage to supply the sensor/actuator blocks. The implantable chip dissipates 595 μW and requires 1.48 V for start up.

Efficient hybrid neural network for spike sorting

Artificial neural network has been used successfully to develope the automatic spike extraction. In order to address some of the problems before the wireless transmission of the implantable chip, the automatic spike sorting method with low complexity and high efficiency is proposed based on the hybrid neural network with the principal component analysis network (PCAN) and normal boundary response (NBR) self-organizing mapping (SOM) network classifier. An automatic PCAN technique is used to reduce the dimension and eliminate the correlation of the spike signal. The NBR-SOM network performs the spike sorting challenge and improves the classification performance. The experimental results show that based on the hybrid neural network, the spike sorting method achieves the accuracy above 97.91% with signals containing five classes. The proposed NBR-SOM network classifier is to further improve the stability and effectiveness of the classification system.

Remote-Controlled Medicine

Implanted devices have been in use for decades to deliver certain drugs (typically, a single drug via a specific blood vessel that supplies relevant organs). Now, a multi-institutional team reports that it has developed an implantable chip that can release precise …

RFID Terminology and Technology: Preparing to Evaluate RFID for Your Library

Radio Frequency Identification (RFID) has arrived. It is commonly used in areas as diverse as warehouses and implantable identification chips for pets and livestock. As with any technology, the evaluator must learn certain concepts and terminology. This article presents various basic concepts of RFID and indicates applicability in the library setting. It provides a foundation for addressing privacy concerns regarding the use of RFID in the library. For those considering implementing RFID in their institution, it provides suggested resources for further reading.

A 2 MHz Wireless CMOS Transceiver for Implantable Biosignal Sensing Systems

An implementation of an implantable sensing biosystem composes of a readout circuit, a power management block, an embedded microcontroller unit (MCU), an implantable drug delivery section and a wireless uplink transceiver system. This paper describes a bi-directional wireless transceiver system for implantable sensing systems. The transceiver system is composed of an external and implantable transceiver, communicating through an inductive link. Half duplex communication between transceivers at a 10 Kbps data rate was achieved at a maximum distance of 4 cm. Command and data will be supplied to the implantable module by radio frequency (RF) telemetry utilizing an amplitude shift keying (ASK) modulated 2 MHz carrier frequency. A capacitor-less amplitude demodulation receiver architecture was produced in the research with implantable receiver core area measuring at 113.2 µm by 171.8 µm with average power dissipation at 815.1 µW at a 3.3 V single rail power supply. An active uplink transceiver utilizing load shift keying (LSK) as backward data telemetry was designed. Implantable transmitter core area measures 251.7 µm by 139.3 µm, consuming 103.62 mW while driving an RF ferrite core antenna at maximum reading range. Integrating both circuits, implantable transceiver, measuring 355.3 µm by 171.8 µm, was designed and implemented using TSMC 0.35 µm mixed-signal 2P4M 3.3 V standard CMOS process. The integrated circuit solution addressed solutions for many of the problems associated with implanted devices and introduces circuits which improve in several ways over previously published designs, in functionality and integration level. In addition to being fully integrated in plain CMOS technology, not relying at least partly on available specialized elements and expensive technologies, these building blocks improve on previous designs in performance and/or power consumption. This work succeeded in implementing building blocks for an implantable transceiver, which depends only on the absolute minimum off-chip components. A complete implantable chip is presented, which highlight the design tradeoffs and optimizations applied to the design of CMOS implantable system chips.

Pacemakers charging using body energy

Life-saving medical implants like pacemakers and defibrillators face a big drawback that their batteries eventually run out and patients require frequent surgery to have these batteries replaced. With the advent of technology, alternatives can be provided for such surgeries. To power these devices, body energy harvesting techniques may be employed. Some of the power sources are patient's heartbeat, blood flow inside the vessels, movement of the body parts, and the body temperature (heat). Different types of sensors are employed, such as for sensing the energy from the heartbeat the piezoelectric and semiconducting coupled nanowires are used that convert the mechanical energy into electricity. Similarly, for sensing the blood flow energy, nanogenerators driven by ultrasonic waves are used that have the ability to directly convert the hydraulic energy in human body to electrical energy. Another consideration is to use body heat employing biothermal battery to generate electricity using multiple arrays of thermoelectric generators built into an implantable chip. These generators exploit the well-known thermocouple effect. For the biothermal device to work, it needs a 2°C temperature difference across it. But there are many parts of the body where a temperature difference of 5°C exists – typically in the few millimeters just below the skin, where it is planned to place this device. This study focuses on using body heat as an alternative energy source to recharge pacemaker batteries and other medical devices and prevent the possibility of life-risk during repeated surgery.

Oxygen sensitivity and biocompatibility of an implantable paramagnetic probe for repeated measurements of tissue oxygenation.

The use of oxygen-sensing water-insoluble paramagnetic probes, such as lithium octa-n-butoxynaphthalocyanine (LiNc-BuO), enables repeated measurements of pO(2) from the same location in tissue by electron paramagnetic resonance (EPR) spectroscopy. In order to facilitate direct in vivo application, and hence eventual clinical applicability, of LiNc-BuO, we encapsulated LiNc-BuO microcrystals in polydimethylsiloxane (PDMS), an oxygen-permeable and bioinert polymer, and developed an implantable chip. In vitro evaluation of the chip, performed under conditions of sterilization, high-energy irradiation, and exposure to cultured cells, revealed that it is biostable and biocompatible. Implantation of the chip in the gastrocnemius muscle tissue of mice showed that it is capable of repeated and real-time measurements of tissue oxygenation for an extended period. Functional evaluation using a murine tumor model established the suitability and applicability of the chip for monitoring tumor oxygenation. This study establishes PDMS-encapsulated LiNc-BuO as a promising choice of probe for clinical EPR oximetry.