Sensors and Imagers

11:00 – VIS and NIR LED based Voltage-Tunable Sensor for Material Classification

This study introduces a cost-effective and energy-efficient material classification system designed to enhance recycling and waste management efficiency. The system employs a voltage-tunable germanium-on-silicon (Ge-on-Si) photodetector, operating across the 400–1600 nm wavelength range, to distinguish seven material types, including plastics, aluminum, glass, and paper. To ensure broad spectral coverage and stable operation, the system integrates three low-power LED light sources—one in the visible (VIS) range and two in the short wavelength infrared (SWIR) range. The simplified optical setup and compact sensor holder reduce mechanical complexity, enabling easy integration into automated sorting platforms. Classification is achieved by analyzing photocurrent responses under varying bias voltages using machine learning algorithms. Empirical results demonstrate rapid and accurate material identification with minimal power consumption, highlighting the system’s potential for scalable and sustainable deployment in modern waste sorting infrastructure.

11:20 – Testing the Reliability of 2D MEMS Mirrors by Increasing the Applied Stress Over Time

The reliability assessment and failure analysis of Microelectromechanical System (MEMS) mirrors is a rather new research area, where especially the influence of environmental and mechanical loads on the performance needs to be evaluated. The aim of this work is to test the reliability of 2D resonant MEMS mirrors, which are driven electrostatically, under applied stress in order to find out after which time and at which stress levels the function of the mirror is affected or a breakage occurs. With the help of the used test setup several mirrors could be tested simultaneously and different mirror parameters could be logged. Measurements have been executed with a duration of approximately one month, where the mirrors were stressed by increasing the oscillation angle over time. The results showed that there are mirror parameters, which may indicate a failure of the mirror before it occurs. Especially a negative drift of the mirror frequency was observed before breakage. Additionally the results showed a correlation between temperature and mirror frequency and information about the distribution of the stress levels at which the mirrors break was gathered.

11:40 – Read-Out and Electrical Connection of Modern High-Purity Germanium Detectors: Innovative Flexible Systems and Integrated Charge-Sensitive Pre-amplifiers

Segmented high-purity germanium detectors are at the heart of cutting-edge gamma spectroscopy. However, their technical and manufacturing specifications are not known, since they are provided by industry. To bridge this gap, Italy’s INFN launched the N3G Project, an initiative to design new segmented high-purity germanium detectors while acquiring the technical expertise to build, manage, and maintain them independently. In this framework, the current paper offers a novel contribution. The innovative system designed to electrically connect the electrodes of the detector to the front-end electronics will be described and its low impact on the detector leakage current will be shown. Moreover, the architecture of a new integrated charge sensitive pre-amplifier will be reported and its validation will be presented. The circuit demonstrated excellent linearity and low noise. An integral non-linearity factor of 0.04 % was found and an optimum equivalent noise charge of 108 root-mean-square electrons was measured for a 15 pF equivalent electrode capacitance.

12:00 – TCAD simulation of a SEBAT coupled to a THz detector in 150nm CMOS

This work provides an in-depth analysis of a Single Electron Bipolar Avalanche Transistor (SEBAT) fabricated in a 150nm CMOS process through TCAD simulations. The device has been integrated with a FET detector to achieve its primary objective of detecting THz waves. Moreover, valuable insights into the performance limitations of existing SEBAT design are demonstrated. Experimental measurements conducted on the transistor reveal inefficient generation of avalanche pulse counts if compared to the flux of injected electrons that motivate the creation of enhanced detector designs. The paper explores methods to significantly improve individual device performance through a comprehensive redesign of the SEBAT geometry and integration scheme.

12:20 – Photovoltaic Imaging in Standard BiCMOS with an Open-Circuit Voltage Pixel

A pixel unit cell utilizing the photovoltaic regime of the detector and a subthreshold common-source amplifier is proposed. A prototype 128 × 128 front-side illuminated visible image sensor fabricated in standard 0.13μm BiCMOS was developed to validate the pixel topology. Additionally, single-element photodiode arrays compatible with standard CMOS or BiCMOS processes were fabricated, characterized, and evaluated for photodetector performance. The standard photodiodes show measured dark current density and resistance-area product in the range of 0.82 - 1.99 μA/cm2 and 6.1 - 22 Ω×cm², respectively. The p+/n-well photodiodes show peak quantum efficiency of 14.5% at 0.7μm peak wavelength. The open-circuit voltage pixel (VocP) enables increased “effective” responsivity of the photodiode enabling sensitive imaging in “standard CMOS”. Noise-equivalent power (NEP) of < 300f W/√Hz is demonstrated for the prototype array. The pixel and detector techniques developed are realizable in low-cost, standard CMOS.

12:40 – Design and Application of a Silicon Photomultiplier-based Platform for Biosensing

This work describes an optoelectronic platform integrating highly sensitive silicon photomultiplier detectors with custom computer-based signal conditioning to detect bioluminescence from genetically modified bacteria engineered to respond to environmental contaminants. A suitably developed algorithm controls the acquisition rate, ensuring reliable performance across varying environmental conditions and different bacterial growth stages. To minimize potential interference from ambient light and electromagnetic sources, a custom-designed dark box was manufactured and rigorously tested to ensure its effectiveness. The platform can monitor up to four samples simultaneously, enabling more robust statistical analysis and direct biosensor calibration, a crucial feature when working with dynamic systems like bacterial populations. The system was tested with the low-intensity bioluminescent signals produced by engineered Escherichia coli in response to mercury exposure. A remarkable detection sensitivity of 0.25 μg/L –four times below current regulatory standards– was obtained, with a wide dynamic response range spanning approximately two orders of magnitude.