Biomedical Circuits and Systems II

11:00 – Programmable Floating Inverter-Based Digital OTA for Electrochemical Biosensing

In this paper, an ultra-low voltage (ULV), ultra-low power (ULP), programmable Floating Inverter (FI)-based Digital Operational Transconductance Amplifier (FI-DIGOTA) for electrochemical biosensors is presented and demonstrated in 130 nm CMOS technology. The proposed FI-DIGOTA operates at a power supply voltage ranging from 300 mV to 500 mV and drives a capacitive load up to units of μF, which is consistent with the double-layer capacitance of a commercial screen printed electrode in a physiological solution. The DC gain ranges from 41.18 dB to 62.15 dB, the Gain-Bandwidth Product (GBW) spans from 25.9 Hz to 293 Hz with a power consumption ranging from 3.05 nW to 1,572.55 nW.

11:20 – An Improved Charge Recycling Bipolar Pulser Architecture for Ultrasound Imaging

High-voltage pulsers are crucial in medical ultrasound imaging systems, significantly influencing both transmitter's signal quality and power efficiency. In this context, we introduce a new structure for a 5-level bipolar pulser based on a voltage-doubling architecture, that is extended with four additional switches to enable charge recycling and dual-supply operation. Circuit-level simulations demonstrate substantial improvements, including reduced power consumption, enhanced harmonic rejection and higher fundamental output voltage.

11:40 – An Ultra Low-Power LC-ADC Using Oxide TFT Technology for ECG Signals Processing

This manuscript presents an ultra-low-power level-crossing analog-to-digital converter (LC-ADC) using amorphous indium gallium zinc oxide (a-IGZO) thin-film single-gate transistor technology for the first time. The entire circuit is implemented with unipolar oxide TFTs (n-type), which is compatible with flexible substrate to facilitate conformal wearable devices. The proposed LC-ADC consists of a single multi-level comparator along with control logic to generate time based spikes. The use of a single multi-level comparator leads to a simplified architecture and an energy-efficient topology. This circuit has shown an ENOB of 4.9 bits, SFDR of 34.8 dB, a power dissipation of 6 μW at a VDD of 2 V, when the input signal frequency is 100 Hz. To demonstrate the suitability of the circuit for biomedical applications, reconstruction of sine wave and ECG signal has been demonstrated. The crucial ECG parameters such PR, QT, QRS and ST interval are intact in the reconstructed signal.

12:00 – Impact of the Sensor Electrical Noise on Ionoacoustic Dose Reconstruction using 200 MeV Clinical Proton Beam

Ionoacoustic dosimetry has emerged as a promising technique for real-time dose verification in proton therapy, where conventional methods like Electronic Portal Imaging Devices (EPIDs) are ineffective due to the absence of an exit dose beyond the Bragg peak. This study evaluates the impact of realistic sensor noise on the ionoacoustic reconstruction of dose distributions generated by a 200 MeV proton beam, simulated using the k-Wave toolbox. Different signal-to-noise ratios (SNRs) were modeled by varying the delivered dose per pulse across a range of clinically relevant values (1–100 mGy). The quality of the reconstructed dose distributions was assessed using gamma index analysis at 1%/1 mm and 3%/3 mm criteria. Results demonstrate that, even under significant noise conditions, accurate dose reconstructions are achievable without the need for temporal averaging, provided sufficient per-pulse dose. These findings support the feasibility of ionoacoustic dosimetry for online, high-precision proton therapy monitoring and suggest pathways for future experimental validation and clinical translation.

12:20 – Design and Characterization of a Wideband Polyvinylidene Fluoride Ultrasound Sensor for Ionoacoustic Particle Therapy Monitoring

Accurate localization of the Bragg peak is critical in proton therapy to ensure precise dose delivery to tumors while minimizing damage to surrounding healthy tissues. Ionoacoustics is an emerging technique that exploits the acoustic signature of particle beams to make accurate range and dosimetric measurements. This work presents the modeling, design and experimental characterization of a ionoacoustic ultrasound sensor for Bragg peak localization in proton therapy. The study focuses on enhancing sensor performance through finite element method (FEM) simulations, analyzing both frequency response and time-domain behavior to optimize sensitivity and signal detection. Simulation results are validated on experimental acoustic test bench to assess the sensor's response under controlled conditions. The combination of FEM modeling and experimental verification provides insights into improving sensor design for real-time, high-precision proton range verification.