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Solid-state complementary metal oxide semiconductor (CMOS)-compatible glucose fuel cells, with carbon nano horn (CNH) films with different amounts of CNH (wt.%) and glucose solution were investigated. CNH content of 3 wt.% with 30 mM glucose solution was found the highest open circuit voltage (OCV) of 420 mV, a power density of 2.83 µW/cm2 and current density of 6.73 µA/cm2. This is the highest value compared with the conventional glucose fuel cell. The OCV and power density increased together with the fuel cell concentration. The developed fuel cell uses materials that are bio-compatible with the human body (CNH-glucose). As a result, OCV of 420 mV with a CNH content of 3 wt.% while improvements in the performance of the CMOS-compatible fuel cell were obtained, and the parameters affecting the performance of the fuel cell were identified. This glucose fuel cell was fabricated using CMOS semiconductor processes on a silicon wafer. This work presents a (5 mm × 5 mm) solid-state CMOS compatible glucose fuel cell that 420 mV of OCV. It is the highest value for a glucose fuel cell when the anode area is (4.2 mm × 4.6 mm). These findings are significant in realizing mobile or implantable devices that can be used for biomedical applications.

Solid-state complementary metal oxide semiconductor (CMOS)-compatible glucose fuel cells, with single-walled carbon nanotube (SWCNT) films and different amounts of carbon nanotube (wt%) were investigated. Those with a SWCNT content of 3 wt% were found to develop the highest open circuit voltage (OCV) of 400 mV, together with a high electrical conductivity, a power density of 0.53 μW/cm2 and current density of 1.31 μA/cm2. Measurements were performed by dipping the anode into a 30 mM glucose solution. The OCV and power density increased together with the fuel cell concentration. The developed fuel cell uses materials that are biocompatible with the human body (single-walled carbon nanotube-glucose). As a result, it was possible to attain an OCV of 400 mV with a single-walled carbon nanotube content of 3 wt% while improvements in the performance of the CMOS-compatible glucose fuel cell were obtained, and the parameters affecting the performance of the fuel cell were identified. This bio-fuel cell was fabricated using CMOS semiconductor processes on a silicon wafer. These findings are significant to realizing mobile or implantable devices that can be used for biomedical applications.

This brief presents the lowest-current fully integrated sub-mm3 OOK transmitter, the transmission of which is modulated by its supply voltage. By combining the transmitter with a glucose fuel cell that functions as both the power source and sensing transducer, a self-powered continuous glucose monitoring system (CGMS) contact lens can be emerged. The prototype in 55-nm deeply depleted channel CMOS with on-chip inductor and antenna requires an average current of 6.1 nA under 0.32-V supply without any external signal, which demonstrates the potential for self-powered operation.

This paper proposes a self-powered disposable supply-sensing biosensor platform for big-data-based healthcare applications. The proposed supply-sensing biosensor platform is based on bio fuel cells and a 0.23-V 0.25- $\mu \text{m}$ zero- $V_{\text {th}}$ all-digital CMOS supply-controlled ring oscillator with a current-driven pulse-interval-modulated inductive-coupling transmitter. The fully digital, and current-driven architecture uses zero- $V_{\text {th}}$ transistors, which enables low voltage operation and a small footprint, even in a cost-competitive legacy CMOS. This enables converterless self-powered operation using a bio fuel cell, which is ideal for disposable healthcare applications. To verify the effectiveness of the proposed platform, a test chip was fabricated using 0.25- $\mu \text{m}$ CMOS technology. The experimental results successfully demonstrate operation with a 0.23-V supply, which is the lowest supply voltage reported for proximity transmitters. A self-powered biosensing operation using organic bio fuel cells was also successfully demonstrated. In addition, an asynchronous inductive-coupling receiver and an off-chip inductor for performance improvement were successfully demonstrated.

This work proposes a solar-cell-assisted wireless biosensing system that operates using a biofuel cell (BFC). To facilitate the reduction of the BFC area and apply this system to area-constrained continuous glucose monitoring (CGM) contact lenses, an energy harvester combined with an on-chip solar cell is introduced as a dedicated power source for the transmitter. A dual-oscillator-based supply voltage monitor is employed to convert the BFC output into digital codes. From measurements of the test chip fabricated with the 65-nm CMOS technology, the proposed system can achieve BFC area reduction of 99.66%.

This paper presents a self-controlled dual-oscillator-based supply voltage monitor for biofuel-cell-combined biosensing systems. First, the proposed self-triggered architecture enables self-control without requiring any external control signals. Second, the proposed frequency subtraction with two gate-leakage-based oscillators with different supply sensitivities enables low-power, small-footprint, and accurate supply voltage monitoring. The proposed supply voltage monitor converts the change in supply voltage into a digital supply voltage code. The proposed supply voltage monitor is fabricated using 65-nm CMOS technology with an active area of 0.0047 mm2, and it shows an operating supply voltage range of 250 mV (0.75-1 V). It consumes a standby power of 1.4 nW at a supply voltage of 0.75 V and has a voltage resolution of 2.4 mV. Furthermore, the measurement results show a peak-to-peak inaccuracy of+12.1 mV/-8.4 mV.

In this study, we developed an AI-based edge-intelligent hypoglycemia prediction system for the environment with low-periodic blood glucose level. By using long-short-term memory (LSTM), a specialized network for handling time series data among neural networks along with introducing alternate learning and inference, it was possible to predict the BG level with high accuracy. In order to achieve, the system for predicting the blood glucose level was created using LSTM, and the performance of the system was evaluated using the method of the classification problem. The system was successfully predicted the probability of occurrence of hypoglycemia after 30 min at approximately 80% times. Furthermore, it was demonstrated that accuracy is improved by alternately performing learning and prediction.

A design of gate-leakage-based timer using an amplifier-less replica-bias switching technique that can realize stable and low-voltage operation is presented. To generate stable oscillation frequency, the topology that discharges the pre-charged capacitor via a gate leaking MOS capacitor with low-leakage switch and logic circuits is employed. The test chip fabricated in 55-nm deeply depleted channel (DDC) CMOS technology achieves an Allan deviation floor of 200 ppm at a supply voltage of 350 mV in a 0.0022 mm2 area.

This work presents the lowest power consumption sub-mm2 supply modulated OOK transmitter for enabling self-powered continuous glucose monitoring (CGM) contact lens. By combining the transmitter with a glucose fuel cell which functions as both the power source and sensing transducer, self-powered CGM contact lens can be emerged. The 385 x 385 μm2 test chip implemented in 65-nm standard CMOS technology operates 270pW under 0.165V and successfully demonstrates self-powered operation using 2 x 2 mm2 solid-state glucose fuel cell.

Solid-state complementary metal oxide semiconductor (CMOS)-compatible glucose fuel cells, with carbon nano horn (CNH) films with different amounts of CNH (wt.%) and glucose solution were investigated. CNH content of 3 wt.% with 30 mM glucose solution was found the highest open circuit voltage (OCV) of 420 mV, a power density of 2.83 µW/cm2 and current density of 6.73 µA/cm2. This is the highest value compared with the conventional glucose fuel cell. The OCV and power density increased together with the fuel cell concentration. The developed fuel cell uses materials that are bio-compatible with the human body (CNH-glucose). As a result, OCV of 420 mV with a CNH content of 3 wt.% while improvements in the performance of the CMOS-compatible fuel cell were obtained, and the parameters affecting the performance of the fuel cell were identified. This glucose fuel cell was fabricated using CMOS semiconductor processes on a silicon wafer. This work presents a (5 mm × 5 mm) solid-state CMOS compatible glucose fuel cell that 420 mV of OCV. It is the highest value for a glucose fuel cell when the anode area is (4.2 mm × 4.6 mm). These findings are significant in realizing mobile or implantable devices that can be used for biomedical applications.

This paper presents a stochastic oscillator using multiple ring oscillators and OR-gate intended for low supply voltage operation for the first time. For achieving low supply voltage operation under considerable process variations, multiple ring oscillators are employed. By using OR gates, the ring oscillator with lowest voltage capability can be utilized, which was confirmed by SPICE simulations. The prototype is fabricated in 65nm CMOS technology. Measurement results shows effectiveness of the proposal.

In order to care and prevent diabetes, continuous glucose monitoring (CGM) is considerably important [1]. However, existing needle-type glucose monitoring systems [2] are painful, thus unsuitable for preventing applications. In order to address this issue, a needle-less and pain-free CGM contact lens has been developed [3]. Since tear glucose level has high correlation with blood glucose level, it can be expected to be future de facto standard CGM. However, the existing CGM contact lens is based on RFID technology associated with the dedicated smart glasses, which degrade the patients' comfort and cost too much.

This paper presents a bit error rate (BER)-modulated inductive-coupling transceiver using dynamic intermediate interference control technique for the first time. By controlling interference from the intermediate writer, BER can be modulated. SPICE simulation is performed in 65-nm CMOS. The simulation results show that the proposed approach is effective for power and cost reduction of the writer.

This work presents world's lowest power consumption sub-mm2supply-modulated CMOS OOK transmitter for enabling self-powered continuous glucose monitoring contact lens. By introducing self-oscillating voltage doubler and charge pump, compact, low-voltage, low-power supply-modulated OOK transmitter become available. By prototyping 385 μm × 385 μm testchip in 65nm standard CMOS technology, 0.27 nW under 0.165 V performance and self-powered operation using 2 mm × 2 mm solid-state glucose fuel cell were sucessfully demonstrated.

A blood glucose level prediction system that uses machine learning with a recurrent neural network is presented, to prevents hypoglycemia. By introducing machine learning associated with a recurrent neural network, a high accuracy can be obtained with only a time-series of the blood glucose level. For verifying the proposed method, the system is evaluated from the following viewpoints: the alert frequency, the accuracy rate of the alerts, and the prediction of hypoglycemia after 30 min. The system is able to achieve a prediction accuracy of approximately 80%. In addition, the possibility of a further performance improvement by increasing the frequency of blood glucose measurement is verified. Finally, a method for optimizing the hyperparameters according to the operating period is presented.

This paper presents a gate-leakage-based timer using an amplifier-less replica-bias switching technique that can realize stable and low-voltage operation with logic circuits based architecture. To generate stable oscillation frequency in low power operation, the topology that discharges the pre-charged capacitor via a gate leaking MOS capacitor with low-leakage switch is employed. The proposed amplifier-less replica-bias switching technique enables the low-voltage operation of the timer by tracking the discharging node of the capacitor and minimizing the leakages through the switch without analog circuits. The native NMOS header is implemented to reduce supply sensitivity of the timer. The test chip fabricated in 55-nm deeply depleted channel (DDC) CMOS technology achieves an energy efficiency of 25 pJ/cycle at a supply voltage of 350 mV with a body bias in a 0.0022 mm2 area, and 200-ppm Allan deviation floor.

Fabrication of a 0.36 mm2 (0.6 mm × 0.6 mm) solid-state CMOS-compatible glucose fuel cell, which delivers 12% yield and a highest reported open circuit voltage (OCV) of 370 mV, is presented. The introduction of repeated separator coating helps avoid electrical short-circuiting between the anode and cathode of the fuel cell, resulting in a higher yield as compared to that when the conventional single coating is used. Higher yield allows improvement in the value of peak OCV. The measurement results show an OCV of 370 mV and a 12% yield with a 30 mM glucose solution.