An Auto Adjustable Transimpedance Readout System for Wearable Healthcare Devices

Abstract

The objective of this work was to design a versatile readout circuit for patch-type wearable devices consisting of a Transimpedance Amplifier (TIA). The TIA performs Current to Voltage (I–V) conversion, the most widely used technique for amperometry and impedance measurement for various types of electrochemical sensors. The proposed readout circuit employs a digitally controllable feedback resistor (Rf) technique in the TIA to improve accuracy, which can be utilized in a variety of electrochemical sensors within a current range of 0.1 µA–100 µA. It is designed to accommodate multiple sensors simultaneously to track multiple target analytes for high accuracy and versatile usage. The readout circuit consists of low power operational amplifier (op–amp) and digital circuit blocks, is designed and fabricated with Magna 0.18 µm Complementary Metal Oxide Semiconductor (CMOS) technology, which provides low power consumption and a high degree of integration. The design has a small size of 0.282 mm2 and low power consumption of 0.38 mW with a 3.3 V power supply, which are desirable factors in wearable device applications.

A 180 nm CMOS Integrated Optoelectronic Sensing System for Biomedical Applications

“…These requirements can be fulfilled by employing integrated optoelectronics sensors in standard CMOS technology combined with digital-based pulse-wave analysis techniques [9,10]. Optical sensor systems are also widely used in other fields of safety-healthcare applications, such as in wearable prosthetic systems [11][12][13][14], where a single or array of sensors are designed to increase the day-to-day patient life quality. Another important application of wearable optical sensors is the continuous environmental monitoring of workplaces where hazardous gases or nano-and/or micro-sized pollutants are employed with the aim of guaranteeing the health and safety of persons there operating [15][16][17].…”

Watch-Type Dual-Mode Wearable Health Device

“…Many researchers have reported multiple types of WHD to detect biomarkers for physiological signal monitoring such as CO , 2 glucose, uric acid, lactic acid, and metabolites, etc. [19][20][21][22][23][24][25][26][27] One research group, Tipparaju et al have developed a watch-type of wearable transcutaneous CO 2 monitoring device that utilizes an infrared sensor. It can be widely used in the remote assessment of pulmonary gas exchange efficiency for patients with respiratory diseases, like COVID-19, sleep apnea, and chronic obstructive pulmonary disease.…”