Ifana Mahbub

A Low-Power 1-V Potentiostat for Glucose Sensors

In this brief, a 1-V potentiostat circuit for a glucose sensor has been proposed. Test results of this 1-V potentiostat demonstrate high linearity with respect to glucose concentration, which is comparable with conventional potentiostat designs. This high linearity is achieved with the help of a transconductance enhanced bulk-driven operational amplifier. The overall current consumption of the circuit is around 22 μA. The potentiostat is tested as a glucose biosensor for glucose concentration ranging from 0 to 30 mM. The design is realized in a 0.35-μm bulk-CMOS process, and the area for the core layout is 0.13 mm2. The proposed low-power potentiostat can be incorporated in an implantable glucose sensor system due to its low-power operation and small footprint.

A low power auto-reconfigurable pipelined ADC for implantable biomedical applications

This paper demonstrates a reconfigurable, pipelined analog-to-digital converter (ADC) that is designed for ultra-low power consumption through the use of weak inversion region-biased transistors. In addition, the converter is able to reconfigure itself into three different modes of operation based on the input signal or a third party signal such as body motion. An adaptation unit is presented which automatically distinguishes high frequency biosignals from low frequency ones and configures the ADC in the appropriate mode of operation. The adaptation unit gives two-bits of control selecting between 8-bit or 10-bit resolution and 73.7 KS/s or 737 KS/s sampling rate. The power consumption of the pipelined ADC and adaptation unit are 680 μW and 180 μW, respectively, with a 1.8 V supply voltage. The core circuit occupies only 0.425 mm2 area.

Impulse radio ultra-wideband (IR-UWB) transmitter for low power low data rate biomedical sensor applications

This paper presents a fully integrated (on-off keying) impulse radio ultra-wideband (IR-UWB) transmitter suitable for low-power wireless biomedical sensors. The transmitter operates at 3-5 GHz frequency range with a channel bandwidth of ~2GHz. Implemented in a standard 130-nm CMOS process the proposed transmitter follows on/-off keying (OOK) modulation scheme and consumes an average power of 496 μW with 1.2 V supply voltage. Simulation results show that the pulse duration is 3.5ns and the peak amplitude of the power spectrum is -46.8 dBm/MHz and which fully complies with the FCC spectral mask.

PVDF Sensor Stimulated by Infrared Radiation for Temperature Monitoring in Microfluidic Devices

This paper presents a ferroelectric polymer-based temperature sensor designed for microfluidic devices. The integration of the sensor into a system-on-a-chip platform facilitates quick monitoring of localized temperature of a biological fluid, avoiding errors in the evaluation of thermal evolution of the fluid during analysis. The contact temperature sensor is fabricated by combining a thin pyroelectric film together with an infrared source, which stimulates the active element located on the top of the microfluidic channel. An experimental setup was assembled to validate the analytical model and to characterize the response rate of the device. The evaluation procedure and the operating range of the temperature also make this device suitable for applications where the localized temperature monitoring of biological samples is necessary. Additionally, ease of integration with standard microfluidic devices makes the proposed sensor an attractive option for in situ analysis of biological fluids.

A Low-Power Wireless Piezoelectric Sensor-Based Respiration Monitoring System Realized in CMOS Process

This paper presents a methodology of monitoring respiration pattern using piezoelectric transducer incorporating CMOS integrated circuits for signal processing and data transmission. As a proof of concept, the system has been tested by placing electrodes on human chest using adhesive hydrogel to detect the pulsatile vibration due to respiration. The system can be used either as a wearable device itself or alternatively can be attached to a jacket or a chest belt. The front-end transducer is a piezoelectric material-based sensor, which is comprised of a ferroelectric polymer named polyvinylidene-fluoride (PVDF). PVDF is also biocompatible, which makes the sensor suitable to be used as a wearable device. The charge produced by the sensor is converted to a proportional voltage signal with the help of a charge amplifier designed in a standard 130-nm CMOS process with eight metal and one poly layer. The analog voltage signal acquired from the charge amplifier is then converted into a digital signal using a reconfigurable pipelined analog-to-digital converter for ease of transmission. An impulse-radio ultra-wideband transmitter operating in the frequency range of 3.1–5 GHz is designed for wireless transmission of the data. The smaller footprint, lighter weight, wireless telemetry, and low-cost material along with the low-power integrated CMOS circuitry for signal processing and data transmission make the proposed system an attractive choice for stable respiration monitoring system.

A low power wireless apnea detection system based on pyroelectric sensor

The paper presents a fully integrated system for apnea detection. Apnea has been one of the leading causes of death in the USA and it is even more critical for premature neonatal infants. A prototype device with the pyroelectric sensor and a wireless telemetry designed in 0.5 μm CMOS process is presented which overcomes the complexity of the point of care diagnosis of sleeping disorders.

A low power wireless breathing monitoring system using piezoelectric transducer

The paper presents a continuous breathing pattern monitoring system using a piezoelectric transducer and low power CMOS integrated circuit. The system is compatible for being used as a wearable device around the chest using a belt. The piezoelectric sensor is a ferroelectric polymer which is a biocompatible material. The rest of the integrated circuit is designed using a standard 130 nm CMOS process. The smaller footprint, wireless interface, low-cost and inconvenience-free design features of the proposed system makes it an attractive alternative to conventional methods for continuous breathing pattern monitoring.

A Divide-by-3 0.4–1.4 GHz Injection-Locked Frequency Divider Based on Relaxation Oscillator

In this letter, a new topology for divide-by-3 injection-locked frequency divider based on relaxation oscillator is reported. A prototype is designed and implemented in a 90 nm CMOS process technology. The measurement results demonstrate a locking range of 0.4-1.4 GHz with a power consumption of 30 μW.

A Low-Power Low-Data Rate Impulse Radio Ultra-Wideband (IR-UWB) Transmitter

A low-power and low-data-rate (100 kbps) fully integrated CMOS impulse radio ultra-wideband (IR-UWB) transmitter for biomedical application is presented in this paper. The transmitter is designed using a standard 180-nm CMOS technology that operates at the 3.1-5 GHz frequency range with more than 500 MHz of channel bandwidth. Modulation scheme of this transmitter is based on on-off keying (OOK) in which a short pulse represents binary “1” and absence of a pulse represents binary “0” transmission. During the ‘off’ state (sleep mode) the transmitter consumes only 0.4 μW of power for an operating voltage of 1.8 V while during the impulse transmission state it consumes a power of 36.29 μW. A pulse duration of about 3.5 ns and a peak amplitude of the frequency spectrum of about -47.8 dBm/MHz are obtained in the simulation result which fully complies with Federal Communication Commission (FCC) regulation.

A low power wearable respiration monitoring sensor using pyroelectric transducer

This paper presents a fully integrated low-power wearable respiration monitoring system using a pyroelectric transducer. Many chronic respiratory diseases such as asthma and apnea are leading causes of death worldwide which are even more critical for premature neonatal infants. Currently, the diagnosis of apnea requires the infants to go through overnight clinical sleep analysis, also known as polysomnography for 12 to 24-hour period. During this process numerous sensors are attached to the sensitive skin of the infants resulting in irritation and inconvenience. To overcome this problem a novel point-of-care respiration monitoring system has been proposed. At the front-end of the sensor a PVDF (Polyvinylidene Fluoride) based pyroelectric transducer is used which could be placed under the nasal cavity or inside a cannula of the subject. The charge generated by the transducer due to the nasal air flow is then converted to a proportional voltage signal by an operational transconductance amplifier (OTA) based charge amplifier. The subsequent signal processing blocks detect and process the signal coming out of the charge amplifier if it lies within the voltage range that corresponds to an apneic event. Once the signal is detected an alarm signal is generated indicating the occurrence of an apneic event. The light-weight design and smaller footprint of the transducer as well as the integrated devices make it suitable as a wearable sensor for non-invasive respiration monitoring. A prototype device with the integrated circuit fabricated using 0.5µm CMOS process is presented in the paper which can prevent many major disorders that can lead to neonatal mortality.