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Sigurd Wagner - IEEE Xplore Author Profile

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Large-area electronic (LAE) thin-film transistors (TFTs) with GHz operation frequencies have enabled LAE-based wireless systems [1] . This motivates accurate modeling of GHz TFTs, but existing approaches are limited for two reasons [2] , [3] : (1) analytical models with numerous parameters are impractical for simulating complex circuits and systems; (2) important losses in the GHz regime are overl...Show More
Large-Area Electronics (LAE) consists of circuits and devices fabricated on large substrates for displays [1] and other applications [2 , 3] . The key LAE device is a bottom-gate thin-film transistor (TFT). On substrates with low thermal conductance, such as glass and plastics, operating a TFT will heat it, affecting carrier mobility, and may overheat it to thermal breakdown [ 4 – 6 ] . Here, we u...Show More
Thin-film transistors (TFTs) are typically made with a non-self-aligned bottom-gate process, which causes large parasitic capacitance from the gate and source/drain (S/D) overlaps. While a top-gate structure can effectively reduce the parasitic capacitance, it can lead to a large series resistance between the gated channel and the S/D contacts ( Fig. 1(a) ) due to high resistivity of the as-deposi...Show More
Resonant operation, exploiting high quality-factor planar inductors, has recently enabled gigahertz (GHz) applications for large-area electronics (LAE), providing a new technology platform for large-scale and flexible wireless systems. This work first presents the design, analysis, and characterization methodology of flex-compatible large-area planar inductors. Specifically, three distinct radio f...Show More
Electrically-driven soft robots based on piezoelectric actuators may enable compact form factors and maneuverability in complex environments. In most prior work, piezoelectric actuators are used to control a single degree of freedom. In this work, the coordinated activation of five independent piezoelectric actuators, attached to a common metal foil, is used to implement inchworm-inspired crawling...Show More
Reconfigurable antennas introduce unique and dynamic system capabilities for wireless communication and sensing, by enabling controllable radiation pattern, frequency response, and polarization of electromagnetic (EM) waves. The antenna’s physical dimensions are critical to enhancing control of radiative characteristics, making it necessary to distribute RF control devices across a large-area aper...Show More
Soft robots present unique capabilities, but have been limited by the lack of scalable technologies for construction and the complexity of algorithms for efficient control and motion. These depend on soft-body dynamics, high-dimensional actuation patterns, and external/onboard forces. This paper presents scalable methods and platforms to study the impact of weight distribution and actuation patter...Show More
Resonant operation, exploiting high quality-factor planar inductors, has recently enabled giga-Hertz applications in large-area electronics, opening up a new technology platform for large-scale and flexible wireless systems. This work presents the design, analysis, and characterization methodology of flex-compatible large-area planar inductors with a record-high quality factor of up to 65 in the 2...Show More
Soft robot is an enabling technology for many emerging applications. The operation voltages of many electric soft actuators, i.e., Macro Fiber Composites (MFC) and Dielectric Elastomer Actuators (DEA), are usually in the range of hundreds to thousands of volts. Actuators in a soft robot often need to be coordinated efficiently, precisely or rapidly, to perform useful functions such as crawling, ju...Show More
Large-area electronic (LAE) metal-oxide thin-film transistors (TFTs) with $f_{T}$ and/or $f_{MAX}$ beyond 1 GHz demonstrated over recent years [1]–[3] enable critical circuits and systems towards wireless applications in Internet of Things and 5G/6G (e.g., a 1-GHz phased array for far-field radiation beam steering [4]). Since most existing approaches towards GHz TFTs rely on improved charge-carrie...Show More
Electrostatic actuators provide a promising approach to creating soft robotic sheets, due to their flexible form factor, modular integration, and fast response speed. However, their control requires kilo-Volt signals and understanding of complex dynamics resulting from force interactions by on-board and environmental effects. In this work, we demonstrate an untethered planar five-actuator piezoele...Show More
Recent progress has substantially increased the operating frequency of large-area electronic (LAE) devices. Their integration into circuits has enabled unprecedented system-level capabilities, toward future wireless applications for the Internet of Things (IoT) and 5G/6G. These exploit large dimensions and flexible form factors. In this work, we focus on giga-Hertz (GHz) zinc-oxide (ZnO) thin-film...Show More
Soft robots have drawn great interest due to their ability to take on a rich range of shapes and motions, compared to traditional rigid robots. However, the motions, and underlying statics and dynamics, pose significant challenges to forming well-generalized and robust models necessary for robot design and control. In this work, we demonstrate a five-actuator soft robot capable of complex motions ...Show More
Soft robots have drawn significant attention recently for their ability to achieve rich shapes when interacting with complex environments. However, their elasticity and flexibility compared to rigid robots also pose significant challenges for precise and robust shape control in real-time. Motivated by their potential to operate in highly-constrained environments, as in search-and-rescue operations...Show More
We highlight recent progress in gigahertz large-area electronic (LAE) devices and circuits. On the device level, this relies on advanced design of zinc-oxide (\textZnO) thin-film transistors (TFTs), for which we consider three key figures of merit, i.e., unity current gain frequency fT and unity power gain frequency fMAX of active devices, and unity off-to-on-impedance ratio frequency fcut-off of ...Show More
Future IoT and 5G networks place significant new demands on antennas, where unguided EM waves are generated to access densely distributed sensor nodes. Reconfigurable antennas, capable of changing key parameters (directionality, frequency response, polarization), are starting to play a critical role, but are limited by the assembly of discrete RF components across the large antenna apertures typic...Show More
A number of papers have been published over the past few years demonstrating metal-oxide thin-film-transistors (TFTs) with fT and/or fMAX over 1GHz [1]-[4]. However, these works have focused purely on device-level characterization and have not demonstrated gigahertz circuit operation. In this work, we demonstrate a large-area-compatible metal-oxide TFT-based cross-coupled LC oscillator operating a...Show More
Thin film transistors (TFT's) on flexible large-area substrates enable large-scale deployment of form-fitting embedded and tactile sensors. However, the combination of insulating substrates (e.g., glass, plastics), long metal traces for distributed sensors and circuits over large areas, plasma processing and packaging/assembly for hybrid (CMOS-TFT) systems makes anomalous breakdown in TFT gate die...Show More
Tactile sensing requires form-fitting and dense sensor arrays over large-areas. Hybrid systems, combining Large-Area Electronics (LAE) and silicon-CMOS ICs to respectively provide diverse sensing and high-performance computation/control, enable a platform for such sensing. A key challenge is that hybrid systems require a large number of interfaces between the LAE and CMOS domains, particularly as ...Show More
Tactile sensing has wide-ranging applications, from intelligent surfaces to advanced robotics. Large-Area Electronics (LAE), based on low-temp. fabrication (<;200°C) of thin films, presents distinct capabilities, due to compatibility with a broad range of materials (enabling diverse transducers), as well as large and flexible substrates and materials-deposition methods (enabling expansive and form...Show More
This letter presents a system that enables identification and localization of objects through an array of RFID-readers integrated into a thin sheet via large-area electronics, for lining everyday surfaces. We demonstrate a 5 × 5 active matrix of RFID readers based on thin-hlm transistor (TFT) LC oscillators, using in-house fabricated ZnO TFTs. The array is designed to read commercial ISO14443 13.5...Show More
The tremendous value artificial intelligence (AI) is showing across a broad range of applications is driving it from cyber-systems to systems pervading every aspect of our lives. But real-world data challenges the efficiency and robustness with which AI systems of today can perform, due to the highly dynamic and noisy scenarios they face. While algorithmic solutions are required, this paper also e...Show More
Hybrid systems combine large-area electronics (LAE) with silicon-CMOS ICs for sensing and computation, respectively. In such systems, interfacing a large number of distributed LAE sensors with the CMOS domain poses a key limitation. This paper presents an architecture that aims to greatly reduce both the number of physical connections and the time for accessing all of the sensors. Each sensor modu...Show More
In a photovoltaic device, the evaluation and understanding of carrier-selective contacts are difficult, because in both terminals the current measured represents the sum of both electron and hole currents at that contact. We seek to independently know the electron current and hole current across a carrier-selective contact. In this work, we demonstrate a heterojunction bipolar transistor structure...Show More
In the development of human-centric systems, access to a large number of human information signals is required. Such signals can be acquired from both ambient and on-person (wearable) sensors. Large-area electronics (LAE) provide distinct capabilities for creating the required diverse, distributed and conformal sensors. However, the large volume of and complex correlation to target information wit...Show More