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In this article, three different implementations of an Axon-Hillock circuit are presented, one of the basic building blocks of spiking neural networks. In this work, we explored the design of such circuits using a unipolar thin-film transistor technology based on amorphous InGaZnO, often used for large-area electronics. All the designed circuits are fabricated by direct material deposition and patterning on top of a flexible polyimide substrate. Axon-Hillock circuits presented in this article consistently show great adaptability of the basic properties of a spiking neuron such as output spike frequency adaptation and output spike width adaptation. Additional degrees of adaptability are demonstrated with each of the Axon-Hillock circuit varieties: neuron circuit threshold voltage adaptation, differentiation between input signal importance, and refractory period modulation. The proposed neuron can change its firing frequency up to three orders of magnitude by varying a single voltage brought to a circuit terminal. This allows the neuron to function, and potentially learn, at vastly different timescales that coincide with the biologically meaningful timescales, going from milliseconds to seconds, relevant for circuits meant for interaction with the environment. Thanks to careful design choices, the average measured power consumption is kept in the nW range, realistically allowing upscaling towards the spiking neural networks in the future. The spiking neuron with refractory period modulation presented in this work has an area of 607.3 μm × 492.2 μm, it experimentally demonstrated firing rates as low as 11.926 mHz, and its energy consumption per spike is ≈ 700 pJ at 30 Hz.

This article presents a 24-V high voltage (HV) ultrasonic driver for haptic feedback, designed to drive piezoelectric micromachined ultrasonic transducers (PMUTs) using a unipolar 0.8 $\mu \text{m}$ indium–galium–zinc–oxide (IGZO) thin-film transistor technology fabricated on a polymer substrate. A new hybrid silicon/IGZO DLL architecture is proposed to overcome the IGZO technology shortcomings by leveraging the accuracy and speed capabilities of silicon technologies. The ultrasonic driver is able to drive a transducer capacitance up to 36 pF with a 3.54 bit phase resolution and a frequency of 250 kHz occupying a pitch-matched area per pixel of 800 $\times $ 800 $\mu \text{m}$ . This work shows the first fully integrated high-voltage ultrasonic driver realized in thin-film transistor technology. As the proposed hybrid architecture enables large active driver arrays at a fraction of the cost of silicon solutions, a new range of applications can be envisioned, such as large ultrasonic haptic feedback matrices.

In this work, five different logic architectures [diode-load (DL), dual-input diode-load (DINP-DL), pseudo-CMOS (P-CMOS), crossover, and differential] for digital circuits in amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT) technologies are analyzed and compared. Dual-gate self-aligned (DGSA) lab technology is used to process n-type devices with a-IGZO channel on 6-in glass wafers and flexible substrates. Inverters, ring oscillators, and RFID-compatible 12-bit Manchester-encoded code generator circuits, using different logic architectures, are designed, processed, and characterized. Analyses of unipolar gates are performed to improve the digital design flow for realizing complex digital circuits. A detailed overview compares these logic architectures on different metrics such as robustness, power consumption, performance, and area with the aim of choosing the most optimal logic to comply with the specifications of targeted applications.

Accurate efficiency prediction, improved reliability, and extended lifetime of solar modules are the key driving factors for investment and research in photovoltaic (PV) systems. Enhanced performance and more refined models are realized by incorporating data derived from localized monitoring of solar modules. This work combines interface circuits designed in flexible thin-film transistors (TFTs) with distributed temperature sensors integrated into solar cell lamination enabling in-module within-cell PV monitoring. A TFT multiplexer selects between sensors and is commanded through a serial peripheral interface (SPI) to reduce the IO connections, while the low offset unity-gain TFT buffer enables precise signal transfer. The in-cell sensors together with TFT read-out circuitry demonstrate accurate outdoor temperature monitoring, comparable to silicon integrated circuits.