About

Harbans Dhadwal is an Associate Professor at the Department of Electrical and Computer Engineering at Stony Brook University. His research focuses on integrated fiber optics, fiber optic biosensors, optical signal processing, photon correlation spectroscopy, and inverse problems. His work involves developing advanced optical technologies and methodologies for biosensing and signal analysis, contributing to the fields of bioelectronics and optical sensing systems.

Research topics

• Physics
• Materials science
• Optoelectronics
• Electrical engineering
• Engineering
• Thermodynamics
• Mechanical engineering
• Chemistry
• Composite material

Selected publications

• Laser illumination of multiple capillaries that form a waveguide

  OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 2023-01-23

  articleOpen access1st authorCorresponding

  A system and method are disclosed for efficient laser illumination of the interiors of multiple capillaries simultaneously, and collection of light emitted from them. Capillaries in a parallel array can form an optical waveguide wherein refraction at the cylindrical surfaces confines side-on illuminating light to the core of each successive capillary in the array. Methods are provided for determining conditions where capillaries will form a waveguide and for assessing and minimizing losses due to reflection. Light can be delivered to the arrayed capillaries through an integrated fiber optic transmitter or through a pair of such transmitters aligned coaxially at opposite sides of the array. Light emitted from materials within the capillaries can be carried to a detection system through optical fibers, each of which collects light from a single capillary, with little cross talk between the capillaries. The collection ends of the optical fibers can be in a parallel array with the same spacing as the capillary array, so that the collection fibers can all be aligned to the capillaries simultaneously. Applicability includes improving the efficiency of many analytical methods that use capillaries, including particularly high-throughput DNA sequencing and diagnostic methods based on capillary electrophoresis.

  PublisherOA PDF

• Direct battery electrolyte and supercapacitor heating and temperature maintenance at low temperatures

  2022

  Senior authorCorresponding
  • Materials science
  • Electrical engineering
  • Optoelectronics

  In this paper, the development of a novel technology for direct and rapid heating of battery electrolyte at low temperatures and maintaining the battery temperature at its optimal performance level is presented. The technology has been extensively tested on a wide range of primary and secondary batteries at temperatures as low as -54 deg. C without causing any damage to the batteries. The technology is applicable to almost all primary and secondary batteries, such as Lithium-ion, Lithiumpolymer, NiMH and lead-acid batteries. The technology is also applicable to super-capacitors and has been used to rapidly heat super-capacitors at temperatures as low as -54 deg. C without any damage.

  PublisherDOI

• A hybrid in-parallel TEG-TPV system for harvesting electrical energy from highly varying high-temperature sources

  2022

  Senior authorCorresponding
  • Materials science
  • Optoelectronics
  • Mechanical engineering

  In this paper, a novel heat energy harvesting system that is constructed by a combination of thermoelectric generators (TEG) and thermophotovoltaic (TPV) cells that are configured to operate in parallel is presented. The resulting hybrid TEG-TPV heat energy harvester can therefore generate significantly more electrical energy than is possible for a given TEG surface area. The hybrid TEG-TPV heat energy harvester is designed to generate electrical energy from sources with highly varying and high temperatures. The hybrid harvester is designed to provide a constant temperature gradient to TEG members and allow the TPV cells to operate within their allowable temperature range.

  PublisherDOI

• Observational Clinical Studies of Human Lens Transparency Using the Vision Index Pen

  Translational Vision Science & Technology · 2019-11-15

  articleOpen access

  Purpose: Preventing or delaying the onset of presbyopia and cataract formation remains a challenge. The goal of this study was to establish the utility of the Vision Index Pen (VIP), designed to measure in vivo dynamic light scattering (DLS) from the crystalline lens, in the detection of early cataract or loss of accommodation and to show reproducibility through trials at two independent sites. The gradual loss of transparency of the lens was characterized by the lens crystallin aggregation index (LCX) derived from measured DLS data. Methods: Volunteers in different age groups participated in two independently operated observational clinical studies. All subjects underwent a detailed eye exam and VIP measurement of the intensity correlation of the backscattered light from the lens. Results: LCX values extracted from DLS data show strong correlation with the aging lens, ranging from 20 at the age of 20 years to over 150 at 60 years. Quantitatively significant changes in the LCX value occur from 35 years to 55 years. LCX values were found to correlate with the loss of accommodation (correlation of −0.563 with P < 0.001) and with published data regarding the change in relative lens resistance with age. Conclusions: Results from two independent observational clinical trials have confirmed the repeatability and reproducibility of the VIP diagnostic device as a viable clinical tool for tracking localized macromolecular changes taking place in the aging lens. Detection of early changes in the crystalline lens can be useful in developing patient-specific prediction models, which can be used to screen patients who may benefit from early therapeutic interventions for delaying the onset of presbyopia and cataract growth. Translational Relevance: The VIP diagnostic device provides in vivo access to the human lens, enabling characterization of the unfolding and decomposition of long-lived macromolecules.

  PublisherOA PDFDOI

• In Vivo Observational Clinical Study of Lens Transparency using the Vision Index Pen.

  Investigative Ophthalmology & Visual Science · 2019-07-22

  articleOpen access
  Publisher

• Utility of Vision Index Pen in detecting early cataract and loss of accommodation

  Investigative Ophthalmology & Visual Science · 2018-07-13

  articleOpen accessSenior author
  Publisher

• Collection and Conditioning Circuits

  2017-03-28

  book-chapterSenior author

  In the previous chapters, four commonly used transducers for converting mechanical energy to electrical energy are described, that is, piezoelectric, electrostatic, electromagnetic, and magnetostrictive transducers. In all cases, external mechanical energy is converted to electrical energy and is available at the output of the transducer for collection, conditioning, and delivery to the load. A collection and conditioning (CC) circuit is needed to ensure that the energy demands of the load are satisfied over the entire operating range. In case of sporadic availability of input mechanical energy, an intermediate storage capability may be needed to accumulate the energy to a suitable level. In general, the complexity of the CC circuit is dependent both on the output energy and the voltage/current characteristics of the transducer, and on the energy demands of the load. All transducers considered here produce a time-varying voltage or current, but none are ideal sources; thus, CC circuits are required for each specific system configuration. The time-varying features of the transducer output can be separated into oscillatory, or pulsed periodic, or pulsed sporadic, or even a single pulse. In the latter cases, the peak pulse amplitude as well as duration need to be considered, while for oscillatory outputs, their temporal profile as well as their periodic features must also be considered.

  PublisherDOI

• Mechanical-to-Electrical Energy Conversion Transducers

  2017-03-28

  book-chapterSenior author

  The process of harvesting mechanical energy from the environment and converting it to usable electrical energy can be illustrated as shown in the block diagram of Fig. 2.1. The input mechanical energy to be converted to electrical energy may be in the form of potential energy and/or kinetic energy. The mechanical system providing the mechanical energy for harvesting is hereinafter referred to as the “host system.” The host system may be capable of providing mechanical energy in a number of ways, for example, through linear or rotatory vibration of its structure; through a rocking motion such as experienced in a boat, ship, or buoy; through random relative motion between relatively rigid machine components, such as the motion between different links of a car suspension system; or through shock loading experienced by a weapon platform during firing or target impact. In many cases, and depending on the mechanical-to-electrical energy transducer (electrical generator) being employed, an interfacing mechanism is needed for effective transfer of mechanical energy to the energy-harvesting device. Such interfacing mechanisms may, for example, be needed to amplify force or motion, vary the input force or motion frequency, convert a shock loading impulse to oscillatory or vibratory motion, etc. The interfacing mechanism may perform more than one function depending on the application, the host system, and the transducer characteristics. For example, in many cases, the interfacing mechanism is desired to maximize the rate or amount of mechanical energy transferred to the transducer. In other cases, this mechanism is used to “condition” the available mechanical energy to make the energy transfer possible while protecting the transducer and/or the host system. An interfacing mechanism may connect the structure or a component of the host system directly to the energy-conversion transducer or indirectly via certain intermediate elements such as vibrating structures or magnetic coupling elements.

  PublisherDOI

• Wireless energy and data transfer to munitions using high power laser diodes

  Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2017-05-05 · 1 citations

  article1st authorCorresponding

  In time critical power up applications, such as pre-launch preparation of smart munitions, both power and guidance information needs to be transferred rapidly from the host to the munitions. Tethered solutions are not practical and the existing magnetic inductive charging methods are slow and have limited data transfer rate capability. A wireless solution based on the use of high power laser diodes is presented. Custom dual-junction photo-voltaic cells achieve power conversion efficiencies exceeding 50% at a single wavelength of operation. Energy transfer times of 3.5 s have been achieved for energy levels of 90 J. Guidance and other control data is uploaded to on-board memory devices at a rate of 500 kb/s, through the use of an additional photodiode, which can receive a small fraction of the modulated power beam. A removable collar provides an alignment free charging/data solution enabling rapid deployment of multiple munitions.

  PublisherDOI

• Mechanical-to-Electrical Energy Transducer Interfacing Mechanisms

  2017-03-28

  book-chapterSenior author

  Harvesting electrical energy from mechanical energy of a mechanical (host) system involves the use of transducers (electrical generators) such as those introduced in Chapter 2. In almost all cases an appropriate interfacing (“conditioning”) mechanism is needed for effective integration of the transducer with the source of mechanical energy, i.e., the host system. Such interfacing or conditioning mechanisms may for example be needed to amplify force or displacement or to increase or decrease input displacement or frequency of an input oscillatory motion. Hereinafter, the term interfacing mechanism is intended to refer to those devices that are used to transfer mechanical energy to the transducer, while in some cases performing certain motion and/or force conditioning action. In addition, motion is intended to refer to translational as well as rotational motions. The term “force” is used to also indicate couple, moment, and torque when appropriate. The transfer of mechanical energy to a transducer may be direct or through other intermediate elements in which the mechanical energy may, for example, be stored in the form of potential or kinetic energy and when needed (or a threshold is reached) be released to the transducer for conversion to electrical energy.

  PublisherDOI

Frequent coauthors

• Benjamin Chu

  36 shared

• Romel R. Khan

  State University of New York

  28 shared

• J. Rastegar

  Omnitek Partners (United States)

  23 shared

• Kwang I. Suh

  Halliburton (United Kingdom)

  20 shared

• Rafat R. Ansari

  National Aeronautics and Space Administration

  16 shared

• Anatole P. Kurkov

  National Aeronautics and Space Administration

  11 shared

• Philip Kwok

  Omnitek Partners (United States)

  9 shared

• Renliang Xu

  8 shared

Labs

• Electrical and Computer EngineeringPI