Smartphone-based multispectral imaging: system development and potential for mobile skin diagnosis

We investigate the potential of mobile smartphone-based multispectral imaging for the quantitative diagnosis and management of skin lesions. Recently, various mobile devices such as a smartphone have emerged as healthcare tools. They have been applied for the early diagnosis of nonmalignant and malignant skin diseases. Particularly, when they are combined with an advanced optical imaging technique such as multispectral imaging and analysis, it would be beneficial for the early diagnosis of such skin diseases and for further quantitative prognosis monitoring after treatment at home. Thus, we demonstrate here the development of a smartphone-based multispectral imaging system with high portability and its potential for mobile skin diagnosis. The results suggest that smartphone-based multispectral imaging and analysis has great potential as a healthcare tool for quantitative mobile skin diagnosis. © 2016 Optical Society of America.1

A Multimodal Neural Activity Readout Integrated Circuit for Recording Fluorescence and Electrical Signals

Monitoring the electrical neural signals is an important method for understanding the neuronal mechanism. In particular, in order to perform a cell-type-specific study, it is necessary to observe the concentration of calcium ions using fluorescent indicators in addition to measuring the electrical neural signal. This paper presents a multimodal multichannel neural activity readout integrated circuit that can perform not only electrical neural recording but also fluorescence recording of neural activity for the cell-type-specific study of heterogeneous neuronal cell populations. For monitoring the calcium ions, the photodiode generates the current according to the fluorescence expressed by the reaction between the genetically encoded calcium indicators and calcium ions. The time-based fluorescence recording circuit then records the photodiode current. The electrical neural signal captured by the microelectrode is recorded through the low-noise amplifier, variable gain amplifier, and analog-to-digital converter. The proposed integrated circuit is fabricated in a 1-poly 6-metal (1P6M) 0.18- ??m CMOS process. The fluorescence recording circuit achieves a recording range of 81 dB (75 pA to 860 nA) and consumes a power of 724 nW/channel. The electrical recording circuit achieves an input-referred noise of 2.7 ??Vrms over the bandwidth of 10 kHz, while consuming the power of 4.9 ??W /channel. The functionality of the proposed circuits is verified through the in vivo and in vitro experiments. Compared to the conventional neuroscience tools, which consist of bulky off-chip components, this neural interface is implemented in a compact size to perform multimodal neural recording while consuming low power

Smartphone-based multispectral imaging and machine-learning based analysis for discrimination between seborrheic dermatitis and psoriasis on the scalp

For appropriate treatment, accurate discrimination between seborrheic dermatitis and psoriasis in a timely manner is crucial to avoid complications. However, when they occur on the scalp, differential diagnosis can be challenging using conventional dermascopes. Thus, we employed smartphone-based multispectral imaging and analysis to discriminate between them with high accuracy. A smartphone-based multispectral imaging system, suited for scalp disease diagnosis, was redesigned. We compared the outcomes obtained using machine learning-based and conventional spectral classification methods to achieve better discrimination. The results demonstrated that smartphone-based multispectral imaging and analysis has great potential for discriminating between these diseases. © 2019 Optical Society of America.1

Subthreshold electrical stimulation as a low power electrical treatment for stroke rehabilitation

As a promising future treatment for stroke rehabilitation, researchers have developed direct brain stimulation to manipulate the neural excitability. However, there has been less interest in energy consumption and unexpected side effect caused by electrical stimulation to bring functional recovery for stroke rehabilitation. In this study, we propose an engineering approach with subthreshold electrical stimulation (STES) to bring functional recovery. Here, we show a low level of electrical stimulation boosted causal excitation in connected neurons and strengthened the synaptic weight in a simulation study. We found that STES with motor training enhanced functional recovery after stroke in vivo. STES was shown to induce neural reconstruction, indicated by higher neurite expression in the stimulated regions and correlated changes in behavioral performance and neural spike firing pattern during the rehabilitation process. This will reduce the energy consumption of implantable devices and the side effects caused by stimulating unwanted brain regions. © 2021, The Author(s).1

POWER SUPPLYING APPARATUS FOR NEURAL ACTIVITY RECORDER REDUCING COMMON-MODE SIGNAL APPLIED TO ELECTRODES CONNECTED TO THE NEURAL ACTIVITY RECORDER

Disclosed is a differential voltage supplying apparatus configured to supply, to a neural activity recorder, an input signal generated by combining, with a direct current (DC) power supply, a common-mode signal determined from a voltage applied to a detection electrode and a reference electrode connected to the neural activity recorder, and improve a common-mode rejection ratio of the neural activity recorder and generate a DC power supply

Low-energy integrated circuits and microsystems for implantable wireless neural recording

For real-time monitoring of brain activities, a low-power, high-data-rate, and highly mobile neural recording system is required. This paper discusses how low-energy integrated circuits and microsystems can make contributions to realize such systems with presenting some examples of integrated circuits and microsystems developed for implantable wireless neural recording

A signal folding neural amplifier exploiting neural signal statistics

A novel amplifier for neural recording applications that exploits the 1/fn characteristics of neural signals is described in this paper. Comparison and reset circuits are implemented with the core amplifier to fold a large output waveform into a preset range enabling the use of an ADC with less number of bits for the same effective dynamic range. This also reduces the transmission data rate of the recording chip. Both of these features allow power and area savings at the system level. At the receiver, a reconstruction algorithm is applied in the digital domain to recover the amplified signal from the folded waveform. Other features of this proposed amplifier are increased reliability due to removal of pseudo-resistors, less distortion and low-voltage operation. Meaφsurement results from a 65nm CMOS implementation of a prototype are presented.Accepted versio

A 0.18μm front end for ECG/EEG/neural sensor interface

A 1.8V 0.18μm CMOS analog front end consists of a chopper stabilized low noise preamplifier, a capacitive negative feedback gain stage and a variable gain amplifier with digital tunable low pass filter bank is presented. With optimized gain distribution, the analog front end eliminates the 1/f noise by chopper stabilization without the DC offset cancellation servo loops in conventional chopper amplifier, combines the advantages from chopper stabilization and capacitive negative feedback to achieve both low 1/f noise and compact structure. The simulation results show that the proposed analog front end achieves 32nV/Hz1/2 input referred thermal noise floor with 1.8μA total current from a 1.8V supply, 20kHz chopping frequency, and in-band gain of 400 and 2000, is suitable for electrocardiograph, electroencephalograph, and neural spike recording applications

A single-input dual-output 13.56 MHz CMOS AC-DC converter with comparator-driven rectifiers for implantable devices

A highly efficient single-input, dual-output AC-DC converter for wireless power transfer in implantable devices is implemented using the 0.18-μm CMOS process. The proposed AC-DC converter, consisting of three rectifiers with cross-coupled NMOS transistors and comparator-driven PMOS transistors, achieves up to 79.5% power conversion efficiency at 13.56 MHz operation frequency in order to provide dual outputs of 1.2 V and 2.2 V DC voltages along with 6.2 mA and 22.6 mA of current, respectively, to the implant device from a single RF input. The designed IC consumes a core die area of 0.18 mm2. © 2014 Elsevier Ltd.