Atsuki Kobayashi

An energy-autonomous, disposable, big-data-based supply-sensing biosensor using bio fuel cell and 0.23-V 0.25-μm Zero-Vth all-digital CMOS supply-controlled ring oscillator with inductive transmitter

This study demonstrates an energy-autonomous disposable supply-sensing biosensor platform for big-data-based healthcare application for the first time. The proposed supply-sensing biosensor platform is based on bio fuel cells and a 0.23-V 0.25-μm zero-Vth all-digital CMOS supply-controlled ring oscillator with a current-driven pulse-interval-modulated inductive-coupling transmitter. The all-digital and current-driven architecture using zero-Vth transistors enables low-voltage operation and small footprint even in the cost-competitive legacy CMOS, which enables converterless energy-autonomous operation using bio fuel cell for disposable healthcare application. To verify its effectiveness, a test chip was fabricated using 0.25-μm CMOS technology. The measured results successfully demonstrated operation under a 0.23-V supply, which is the lowest supply voltage among reported proximity transmitters. In addition, an energy-autonomous biosensing operation using organic bio fuel cells for transdermal patch was successfully demonstrated.

A scalable time-domain biosensor array using logarithmic cyclic time-attenuation-based TDC for high-resolution and large-scale bio-imaging

This paper presents a time-domain biosensor array that uses a capacitor-less current-mode analog-to-time converter (CMATC) and logarithmic cyclic time-attenuation-based TDC with discharging acceleration. Combining the exponential function of the CMATC and logarithmic function of the proposed TDC offers linear input-output characteristics. The time-domain property enables bio-imaging at a high spatial resolution and large scale while maintaining scalability. Measurement results with a 0.25-μm test chip successfully demonstrated linear input-output characteristics.

Energy-efficient and low-voltage design methodology for a supply-sensing CMOS biosensor using biofuel cells for energy-autonomous healthcare applications

The power sources of wearable sensors play a key role in sensing-system architecture. As potential power sources for sensors monitoring physiological signals near the human body, biofuel cells, which generate energy from the biological environment through chemical methods, have attracted much attention. However, the insufficient open-circuit voltage of biofuel cells owing to thermodynamic limitation is a basic issue. Thus, the use of biofuel cells as a power supply for a sensor imposes a strict limitation upon the power budget. In this report, we propose a design methodology for a low-voltage supply-sensing CMOS biosensor using biofuel cells. To explore the design methodology for performance optimization, a SPICE simulation was conducted. The simulated results reveal an optimum energy-efficient point in the biosensor design parameters. A fabricated 250 nm CMOS test chip was used to verify the validity of the design methodology and the measurement results matched the simulated results.

A 40 GHz fully integrated circuit with a vector network analyzer and a coplanar-line-based detection area for circulating tumor cell analysis using 65 nm CMOS technology

A 40-GHz fully integrated CMOS-based circuit for circulating tumor cells (CTC) analysis, consisting of an on-chip vector network analyzer (VNA) and a highly sensitive coplanar-line-based detection area is presented in this paper. In this work, we introduce a fully integrated architecture that eliminates unwanted parasitic effects. The proposed analyzer was designed using 65 nm CMOS technology, and SPICE and MWS simulations were used to validate its operation. The simulation confirmed that the proposed circuit can measure S-parameter shifts resulting from the addition of various types of tumor cells to the detection area, the data of which are provided in a previous study: the |S 21| values for HepG2, A549, and HEC-1-A cells are −0.683, −0.580, and −0.623 dB, respectively. Additionally, the measurement demonstrated an S-parameters reduction of −25.7% when a silicone resin was put on the circuit. Hence, the proposed system is expected to contribute to cancer diagnosis.

Three-dimensional millimeter-wave frequency-shift-based CMOS biosensor using vertically stacked LC oscillators

This paper proposes a novel millimeter-wave frequency-shift-based CMOS biosensor capable of providing three-dimensional (3D) resolution. Using vertically stacked LC oscillators, the vertical resolution from the sensor chip surface can be obtained, which enables 3D target detection. Since the shifts in the frequencies of the upper and lower LC oscillators are different because of the changes in the complex dielectric constant of the target, the target can be detected in 3D. To verify the effectiveness of the proposed approach, a test chip was fabricated using a 65 nm CMOS process. The measurement results showed differences in the resonance frequency shifts of the upper and lower LC oscillators, which highlighted the capability of the proposed biosensor to provide 3D resolution.

Design of an energy-autonomous bio-sensing system using a biofuel cell and 0.19V 53μW integrated supply-sensing sensor with a supply-insensitive temperature sensor and inductive-coupling transmitter

This paper presents an energy-autonomous bio-sensing system with the capability of wireless communication. The proposed system includes a biofuel cell as a power source and sensing frontend associated with the integrated supply-sensing sensor. The sensor consists of a digital-based gate leakage timer, supply-insensitive time-domain temperature sensor, and inductive-coupling transmitter. A test chip using 65-nm CMOS technology was operated with a supply of 0.19 V and consumed 53 μW to successfully demonstrate wireless communication with an asynchronous receiver.

Enhancement in open-circuit voltage of implantable CMOS-compatible glucose fuel cell by improving the anodic catalyst

This paper presents an implantable CMOS-compatible glucose fuel cell that generates an open-circuit voltage (OCV) of 880 mV. The developed fuel cell is solid-catalyst-based and manufactured from biocompatible materials; thus, it can be implanted to the human body. Additionally, since the cell can be manufactured using a semiconductor (CMOS) fabrication process, it can also be manufactured together with CMOS circuits on a single silicon wafer. In the literature, an implantable CMOS-compatible glucose fuel cell has been reported. However, its OCV is 192 mV, which is insufficient for CMOS circuit operation. In this work, we have enhanced the performance of the fuel cell by improving the electrocatalytic ability of the anode. The prototype with the newly proposed Pt/carbon nanotube (CNT) anode structure successfully achieved an OCV of 880 mV, which is the highest ever reported.

Design and experimental verification of CMOS magnetic-based microbead detection using an asynchronous intra-chip inductive-coupling transceiver

In this study, an asynchronous intra-chip inductive-coupling transceiver was used to design and experimentally verify a CMOS magnetic-based microbeads detection system. Magnetic microbeads were employed for the surrounding living cells. These microbeads increased the magnetic flux and enabled the operation of an intra-chip inductive-coupling transceiver with a low transmitter supply voltage. Thus, by sensing the change in transmitter supply voltage, the system detected the living cells surrounded by microbeads. To verify the effectiveness of the proposed approach, a test chip was fabricated using 0.25 µm CMOS technology. The measured results successfully demonstrated the detection of microbeads.

A current-mode analog-to-time converter with short-pulse output capability using local intra-cell activation for high-speed time-domain biosensor array

This study demonstrates a current-mode analog-to-time converter (CMATC) enabling short-pulse output capability by using the newly-proposed local intra-cell activation technique, which contributes to the development of high-speed time-domain biosensor array. In the conventional CMATC, the activation pulse is generated globally at the periphery. This limits the output pulse width because of the considerable parasitic word-line capacitance. In this study, a shorter pulse output was achieved by generating the activation pulse locally by using intra-cell configuration without being affected by word-line capacitances. In 1024 × 1024 configuration, 77% pulse width reduction was confirmed using SPICE simulation. A test chip was fabricated using a 0.6 μm standard CMOS process. The measurement results obtained using a sensor chip demonstrate the expected input-output characteristic and 3.36 ns pulse output.

An energy-autonomous bio-sensing system using a biofuel cell and 0.19V 53μW 65nm-CMOS integrated supply-sensing sensor with a supply-insensitive temperature sensor and inductive-coupling transmitter

This paper presents an energy-autonomous bio-sensing system with the capability of proximity communication. The proposed biosensor includes a bio-fuel cell as a power source and sensing front-end associated with the integrated supply-sensing sensor. The sensor consists of a digital-based gate leakage timer, supply-insensitive time-domain temperature sensor, and current-driven inductive-coupling transmitter and achieves low-voltage operation. The timer converts the output supply-voltage from a bio-fuel cell to period output. The supply-insensitive temperature sensor provides PWM output without dependency of the supply voltage. The following inductive-coupling transmitter enables proximity communication. A test chip using 65-nm CMOS technology was operated with a supply of 0.19 V and consumed 53 μW to successfully demonstrate proximity communication with an asynchronous receiver. The measurement results show the possibility of energy-autonomous operation using bio-fuel cells.