Ravinder S. Dahiya

• Professor
• Northeastern University

Transfer printing has been reported recently as a viable route for electronics on flexible substrates. The method involves transferring micro-/macrostructures such as wires or ultra-thin chips from Si (silicon) wafers to the flexible substrates by using elastomeric transfer substrates such as poly(dimethylsiloxane) (PDMS). A major challenge in this...

Printing sensors and electronics over flexible substrates are an area of significant interest due to low-cost fabrication and possibility of obtaining multifunctional electronics over large areas. Over the years, a number of printing technologies have been developed to pattern a wide range of electronic materials on diverse substrates. As further e...

Starting from human ??sense of touch,?? this paper reviews the state of tactile sensing in robotics. The physiology, coding, and transferring tactile data and perceptual importance of the ??sense of touch?? in humans are discussed. Following this, a number of design hints derived for robotic tactile sensing are presented. Various technologies and t...

Email Print Request Permissions Save to Project This paper presents ultra-thin silicon chips (flex-chips) on flexible foils, realized through post-processing steps such as wafer thinning, dicing, and transferring the thinned chips to flexible polyimide foils. The cost effective chemical etching is adopted for wafer thinning and the transfer pri...

A wide variety of tactile (touch) sensors exist today for robotics and related applications. They make use of various transduction methods, smart materials and engineered structures, complex electronics, and sophisticated data processing. While highly useful in themselves, effective utilization of tactile sensors in robotics applications has been s...

Transient electronics, comprising of degradable devices that disintegrate and disappear after their operational life, has received considerable interest in recent years because of the concerns related to the rapidly growing electronic waste (e-waste). However, the degradability or biodegradability of electronic devices alone is insufficient to asce...

Semiconducting nanowires (NWs) hold great potential for high‐performance flexible electronics. However, using them, to fabricate electronic devices, is a complex process requiring multiple lithography steps to address the issues such as the one arising from mismatches between the temperatures needed for NW growth and the temperatures the polymeric...

Transparent light detection devices are attractive for emerging see-through applications such as augmented reality, smart windows and optical communications using light fidelity (Li-Fi). Herein, we present flexible and transparent photodetectors (PDs) using conductive poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS): Ag nanowires...

Following an abiotic or biotic stress, the pH of the extracellular space or the apoplast of a plant can change dramatically, such as wounding that causes an increase in pH or alkalinization. In this proof‐of‐concept‐study, a newly developed carbon‐based bendable potentiometric sensor was tested for the first time in vivo on common bean (Phaseolus v...

Optoelectronic devices, such as photodetectors (PDs), are needed in many applications including high-speed optical communications, robotics, healthcare, and biomimetic visual systems, which require detection and interaction using light. As a result, a wide variety of PDs on planar substrates have been reported using various light sensitive material...

The pursuit of miniaturized Si electronics has revolutionized computing and communication. During recent years, the value addition in electronics has also been achieved through printing, flexible and stretchable electronics form factors, and integration over areas larger than wafer size. Unlike Si semiconductor manufacturing which takes months from...

The intriguing way the receptors in biological skin encode the tactile data has inspired the development of electronic skins (e-skin) with brain-inspired or neuromorphic computing. Starting with local (near sensor) data processing, there is an inherent mechanism in play that helps to scale down the data. This is particularly attractive when one con...

ZnO nanowires (NWs) form an important building block for various types of sensors and field-effect transistors. However, owing to known variability of ZnO structure morphologies, it is challenging to obtain ZnO NWs alone by using synthesis processes such as vapor phase transport (VPT). To address this challenge, we have performed a series of NW syn...

Electronic skin (e-skin), capable of sensing a physical or chemical stimulus and triggering a suitable response, is critical in applications such as healthcare, wearables, robotics, and more. With a substantial number and types of sensors over a large area, the low-cost fabrication is desirable for e-skin. In this regard, printing electronics attra...

Large area electronics (LAE) with the capability to sense and retain information are crucial for advances in applications such as wearables, digital healthcare, and robotics. The big data generated by these sensor-laden systems need to be scaled down or processed locally. In this regard, brain-inspired computing and in-memory computing have attract...

Heterogeneous integration on flexible substrates has been explored in recent years to meet the high‐performance and flexible form factors requirements of several emerging applications. Reliable interconnects, in both 2D and 3D layouts, are critical for the effective use of these systems. But it is challenging to employ conventional bonding and inte...

Stretchable photodetectors (PDs) form an important component of wearable systems used in healthcare applications. High performance and robustness over several cyclic stretching cycles is crucial for these devices to meet the demand of these applications. Herein, we present ZnO nanowires based stretchable PDs that show stable performance for tested...

Printing technology holds great potential for resource‐efficient development of electronic devices and circuits. However, even after decades of research, achieving uniformly responding nanowires (NWs) based printed devices is still a challenge. To date, there is no design rule that clearly guides the fabrication of NW ensemble‐based field‐effect tr...

The photovoltaic devices offer promising eco‐friendly solution for self‐powered flexible electronics. However, their fabrication on flexible substrate is not easy due to mismatches between the requirements of conventional microfabrication and the thermal, and mechanical features of the substrates. Herein, direct roll printed nanoscale photoactive e...

Flexible hybrid electronics (FHE) is an emerging area that combines printed electronics and ultra‐thin chip (UTC) technology to deliver high performance needed in applications such as wearables, robotics, and internet‐of‐things etc. The integration of UTCs on flexible substrates and the access to devices on them requires high resolution interconnec...

Energy harvesting from ambient sources has attracted considerable interest, and triboelectric nanogenerators (TENGs) are the latest among a wide variety of harvesters reported in recent years. While TENGs show notably high voltages, their outputs could be further enhanced with suitable nanofillers. Herein, we demonstrate as-synthesized ultrathin mo...

Zinc oxide (ZnO) nanowires (NWs) are attractive for development of sensitive optoelectronic sensors due to their wide bandgap, high aspect ratio, large surface area, and tunable properties. Due to their abundant surface states, ZnO NWs based devices also experience the bias stress instability, which could open new avenues for development of new sen...

Robust perception is crucial for autonomous and intelligent robots, and this can be achieved through a network of multimodal sensors embedded in the robotic body, like biological organs. Herein, we report a perceptive robotic end-effector, developed using multi-material additive manufacturing, for manipulation of delicate objects. The 3D-printed ph...

Efficient operation of control systems in robotics or autonomous driving targeting real-world navigation scenarios requires perception methods that allow them to understand and adapt to unstructured environments with good accuracy, adaptation, and generality, similar to humans. To address this need, we present a memristor-based differential neuromo...

The integration of high mobility inorganic materials such as silicon (Si) and gallium arsenide (GaAs) onto flexible substrates is a challenging yet crucial step for the development of high-performance flexible electronics. The development of such integration technologies could also lead to hybrid and heterogeneous integration. Herein, we present ‘d...

Highly conductive, transparent, and easily available materials are needed in a wide range of devices, such as sensors, solar cells, and touch screens, as alternatives to expensive and unsustainable materials such as indium tin oxide. Herein, electrospinning was employed to develop fibers of PEDOT:PSS/silver nanowire (AgNW) composites on various sub...

Wearable electronic devices‐laden systems such as electronic‐skin (e‐Skin) have been explored in recent years to enable advances in applications such as Internet of Things, healthcare, and robotics. The power requirement of multitudes of devices in the e‐Skin is a major hurdle for its wider uptake. Herein, a solar cells‐based energy generating e‐Sk...

Efficient operation of intelligent machines in the real world requires methods that allow them to understand and predict the uncertainties presented by the unstructured environments with good accuracy, scalability and generalization, similar to humans. Current methods rely on pretrained networks instead of continuously learning from the dynamic sig...

Highly sensitive pressure sensors, with a wide operating range, are needed in applications such as wearables, prostheses, and haptic‐based interactive systems. Herein, fully 3D printed capacitive pressure sensors comprising polydimethylsiloxane (PDMS) foam‐based dielectric layer, sandwiched between the poly(3,4‐ethylenedioxythiophene):polystyrene s...

Multimaterial 3D printing is an attractive route for low‐cost fabrication of electronic systems having different types of embedded devices. Herein, tunable thermoplastic polyurethane (TPU)‐based conductive composite filaments are presented for development of either strain sensors or different circuit elements. The filaments are developed with two f...

There is a growing interest in the large area, lightweight, low‐power electronic skin (e‐Skin), consisting of a multitude of sensors over conformable surfaces. The use of multifunctional sensors is always challenging, especially when their energy requirements are considered. Herein, the heterogeneous integration of custom‐made flexible organic phot...

Wearable and compliant metallic coils are gaining importance in applications, such as healthcare and Internet of things, for sensing and wireless power and data transfer. This letter presents a resource-efficient and low-cost additive manufacturing (AM)-based microfluidic coils filled with flexible and stretchable liquid metals. The fabrication pro...

This paper presents a biocompatible flexible pressure sensor fabricated by employing a biocompatible organic ferroelectric, namely, single protonated 1,4-diazabicyclo[2.2.2]octane fluoroborate ([Hdabco]BF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ) embedded in poly(vinylidene fluoride) (P...

Flexible, stretchable strain sensors are needed to measure physiological parameters or joint angles in wearable systems and robotics, respectively. This letter presents the stretchable strain sensor that is directly fabricated on environment-friendly Ecoflux substrate. The sensor uses stretchable serpentine-shaped Au interconnects and Ag nanowires...

Out‐of‐plane or 3D electronics on flexible substrates are an interesting direction that can enable novel solutions such as efficient bioelectricity generation and artificial retina. However, the development of devices with such architectures is limited by the lack of suitable fabrication techniques. Additive manufacturing (AM) can but often fail to...

The ever-increasing demand for energy as a result of the growing interest in applications such as Internet of Things (IoT), and wearable systems etc. call for the development of self-sustained energy harvesting solutions. In this regard, the 2D materials have sparked an enormous interest recently, owing to their outstanding properties such as ultra...

Highly sensitive pressure sensors with features such as biocompatibility, biodegradability, and flexibility are needed in applications such as robotics, prosthesis, medical implants, and wearable electronics. However, due to material limitations or technological bottlenecks it is often challenging to fabricate pressure sensors with these attributes...

Piezoelectric materials have been widely used as dynamic force sensors, accelerometers, and energy harvesters. Herein, we report the poly(vinylidene fluoride-co-tetrafluoroethylene) (P(VDF-TrFE)) based transparent piezoelectric nanogenerator (PENG) as a self-powered force sensor. The 2 x 2 array of PENGs was fabricated by sandwiching the P(VDF-TrFE...

Heavy metal ions such as Cu <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2+</sup> are harmful to the environment and our health. Such ions are typically measured using glassy carbon electrode (GCE) based electrochemical sensors developed on rigid substrates. However, several emerging applications re...

Sensor-laden flexible electronic systems offer opportunities to develop a wide range of applications including healthcare, electronic skin (e-skin) in robotics, Internet of Things (IoT) etc. However, the mass production of sensors, needed for these applications, could be a huge challenge when developed with inherently wasteful conventional fabricat...

This paper presents a flexible and disposable humidity sensor based on Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The sensing layer is developed by drop casting PEDOT:PSS on screen printed graphene-carbon (G-C) ink based interdigitated electrodes (IDEs) on paper substrate. The humidity sensing properties are investigated in...

Nanowires (NWs) based sensors have been studied extensively to measure various physical, chemical, and biological parameters as their large surface-to-volume ratio leads to sensitive devices. Further, due to the low flexural rigidity of NWs, these sensors can be developed on ultra-flexible substrates. However, their performance often degrades after...

Conformable and flexible tactile/pressure sensors are of interest in applications such as robotics, wearable and interactive systems to measure the contact forces. These applications require a large number of robust sensors, for which simple manufacturing routes such as additive manufacturing can be useful. Herein, we present the fully 3D printed c...

Printing technologies are changing the face of electronics with features such as resource-efficiency, low-cost, and novel form factors. While significant advances have been made in terms of organic electronics, the high-performance and stable transistors by printing, and their large-scale integration leading to fast integrated circuits remains a ma...

Disposable devices designed for single and/or multiple reliable measurements over a short duration have attracted considerable interest recently. However, these devices often use non-recyclable and non-biodegradable materials and wasteful fabrication methods. Herein, we present ZnO nanowires (NWs) based degradable high-performance UV photodetectors...

The field of additive manufacturing has expanded from single material-based 3D printing to multimaterial printed complex smart structures with intrinsic sensing capability. However, current multimaterial 3D printers allow printing of one material at a time, with limited ability of mixing multiple materials. Herein, we present the new 3D printer whi...

Self-powered flexible pressure sensors are needed in applications such as human-machine interaction. Here, we present a triboelectric nanogenerator (TENG) based self-powered flexible pressure sensor capable of operating over a wide-range of pressures (3.2 - 1176 kPa). The sensor exhibits excellent sensitivities in various regions of the pressure ra...

Flexible hybrid electronics (FHE) offers potential for fast computation and communication needed in applications such as human–machine interfaces, electronic skin, etc. FHE typically comprises devices that can vary from nano‐ to chip scale, and their integration using a common process is often challenging. Herein, a printed electronics route is pre...

The recent advances of portable sensors in flexible and wearable form factors are drawing increasing attention worldwide owing to their requirement applications ranging from health monitoring to environment monitoring. While portability is critical for these applications, real-time data gathering also requires a reliable power supply-which is large...

Biological measurements are often contaminated with large amounts of non-stationary noise which require effective noise reduction techniques. We present a new real-time deep learning algorithm which produces adaptively a signal opposing the noise so that destructive interference occurs. As a proof of concept, we demonstrate the algorithm’s performa...

Estimation of pH is vital to assess the biochemical and biological processes in a wide variety of applications ranging from water to soil, health, and environment monitoring. This work reports a screen-printed flexible and disposable pH sensor using the impedimetric method. The pH sensor was fabricated by screen printing Graphene-Carbon modified Zi...

Sensitive flexible pressure sensors are needed in applications such as health monitoring, robotics, and wearable systems. Herein, crumpled graphene flakes network (c‐GFN) channel based highly sensitive pressure sensing field effect transistors (PRESSFETs) are presented. The solution‐processed PRESSFET devices are developed on ultrathin (≈3 μm thick...

Humidity sensing is crucial for several industrial, environmental, and healthcare applications, many of which require sensors in flexible form factors and with features such as disposability and facile fabrication processes. Herein, we present a flexible, cost-effective, and disposable humidity sensor developed on paper substrate. The screen-printe...

The printed electronics is expected to revolutionize the field of electronics by providing cost‐effective routes for processing diverse electronic materials at temperatures compatible with plastic substrates to develop high‐performance flexible electronics. Building on the achievements of the traditional paper and textile printing industry, and the...

Electronic systems possessing skin‐like morphology and functionalities (electronic skins [e‐skins]) have attracted considerable attention in recent years to provide sensory or haptic feedback in growing areas such as robotics, prosthetics, and interactive systems. However, the main focus thus far has been on the distributed pressure or force sensor...

We propose a novel framework for deep active visuotactile cross-modal robotic object recognition. Our deep neural network (termed xAVTNet) is trained solely with dense visual point cloud data and tested on sparse point clouds acquired from tactile sensors. We propose a novel unsupervised domain adaptation loss function termed VTLoss for minimising...

We propose for the first time, a novel deep active visuotactile cross-modal full-fledged framework for object recognition by autonomous robotic systems. Our proposed network xAVTNet is actively trained with labelled point clouds from a vision sensor with one robot and tested with an active tactile perception strategy to recognise objects never touc...

Nano/microstructures of compound semiconductors such as gallium arsenide (GaAs) demonstrate enormous potential for advanced photonic technologies as they provide realistic means for miniaturization of optoelectronic devices that feature better performance and low power consumption. However, intimately integrating them onto flexible substrates is ch...