A low power sensor signal processing circuit for implantable biosensor applications

Abstract

A low power sensor read-out circuit has been implemented in 0.35 µm CMOS technology that consumes only 400 µW of power and occupies an area of 0.66 mm2. The circuit is capable of converting the current signal from any generic biosensor into an amplitude shift keying (ASK) signal. The on-chip potentiostat biases the chemical sensor electrodes to create the sensor current which is then integrated and buffered to generate a square wave with a frequency proportional to the sensor current level. A programmable frequency divider is incorporated to fix the ASK envelope frequency to be inbetween 20 Hz and 20 kHz, which is within the audible range of human hearing. The entire transmitter block operates with a supply voltage as low as 1.5 V, and it can be easily powered up by an external RF source. Test results emulate the simulation results with good agreement and corroborate the efficacy of the designed system.

Advances in Complementary-Metal–Oxide–Semiconductor-Based Integrated Biosensor Arrays

“…33 Also, in another study, Zhang et al described a potentiostat which maintained the 0.7 V voltage difference between the working and reference electrodes. 52 For an electrochemical biosensor featuring redox enzymes, Huang et al reported a CMOS-based bipotentiostat comprising two readout channels for application of excitation signals and a potential control unit to support redox recycling ( Figure 12). In their study, they achieved high gain and precision with operation in the "1 nA to 10 μA of dynamic range".…”

“…The results of the signal processing circuit shown in Figure 46 were found to be similar to the simulation results. 52 In another study of an implantable biosensor, Hasan et al proposed a low-voltage high-resolution CMOS comparator circuit (Figure 47) for "preamplification of single ended sampled-data", which counterbalances the differential input offset. For easier integration in the biosensor chip, the circuit was made using just 38…”

Simple oscillators-based readout circuit for low-power biomedical implant system

“…As long as the potential difference of 0.7 V is maintained across the WE-RE, the collection electrode (CE) can output a certain current according to the density of analytes (glucose). The potentiostat can be designed in various different ways depending on the output current ranges [19][20][21][22]. In [19], a 16-channel wide-range potentiostat with 6 decades input dynamic range is designed based on the integrator and R-D analogto-digital converter (ADC).…”

“…It will be shown that in our design, 0.2 lA input sensitivity with one decade is sufficient for this sensor system. A 0.7 V potentiostat implemented in a 0.35 lm CMOS process was reported in [20]. In that design, four operational amplifiers (opamps) were utilized which resulted in a large current consumption as well as added complexity due to large number of circuit components.…”

Design and Optimization of Printed Circuit Board Inductors for Wireless Power Transfer System

“…While the wearable sensors are placed outside the body, the implantable types are placed underneath the skin or inside the body cavity typically via surgical means. Implantable sensors are designed to acquire the information on the vital physiological phenomena by monitoring blood glucose level [1][2][3], lactate in the bloodstream or tissues [4], pH, oxygen, and minimally invasive monitoring of pressure in blood vessels and intracranial compartments, etc. [5].…”