Roy Paily

Dr. Roy P. Paily

Professor, Department of Electronics and Electrical Engineering

and Centre for Nanotechnology

IIT Guwahati, Assam, India - 781039

Consultancy/Research Projects:

  1. "Special Manpower Development Programme for Chip to Systems Development (SMDP-C2SD) " at IIT Guwahati, Ministry of Electronics & Information Technology (MeitY), Government of India, from 15-12-2014 till 14-12-2020, (Principal Investigator).
  2. "Centre for Excellence in Research and Development of Nanoelectronic Theranostic Devices" at IIT Guwahati, Department of Electronics & Information Technology, Ministry of Communications & Information Technology, Government of India, from 26-02-2014 till 25-02-2021 (one of the Principal Investigators).
  3. "Design and Implementation of a Blind Assistance System using FPGAs and Sensors" at IIT Guwahati, Department of Information Technology, India, from 23-11-2012 until 22-02-2017 (Principal Investigator).
  4. "Design of Carbon Nanotube Field Effect Transistor (CNFET) based Amplifiers", Global Research Collaboration (GRC) project, funded by Semiconductor Research Corporation, NC, USA, from August 2009 until July 2011 (Principal Investigator).
  5. "Special Manpower Development Project in VLSI Design and related software (SMDP II)" at IIT Guwahati, Department of Information Technology, India, from 08-11-2005 until 31-03-2013 (Investigator) (This is an Institute level project).
  6. "National MEMS Design Center at IIT Guwahati" under National Program on Micro and Smart Systems (NPMASS), from 30-12-2009 until 19-03-2013 (Principal Investigator) (This is an Institute level project).
  7. "Technology Incubation & Development of Entrepreneurs (TIDE) at IIT Guwahati in the areas of Electronics and ICT" Government of India a scheme by Ministry of Communications and Information technology by Department of Information Technology, India, from 09-06-2008 until 08-06-2010 (Principal Investigator) (This is an Institute level project and presently the project is under Technology Incubation Centre, IIT Guwahati).
  8. "Digital VLSI Design Virtual Lab", Under the National Mission on Education through ICT, from 2009 until 2012 (Principal Investigator).
  9. "Design, Fabrication and Testing of a Low Power Analog Front-End Chip for heart rate Detection", Instrument Development Division, Department of Science and Technology, India, from 29-09-2010 until 28-09-12 (Principal Investigator).

Integrated Circuit (Chip) Developments:

  1. Chip 1

    Name of the chip - SANGAI
    Technical specification – 4 Multilayer Inductors, 2.4 GHz VCO, 4 bit flash ADC, NMOS based Amplifier for GHz operation
    Foundary - UMC L180 1P6M MM/RFCMOS process of United Microelectronics Corporation (UMC) through the mini@sic programme of Europractice IC Service.
    Silicon area -1525μm×1525μm
    Test report – Two structures of outer diameter 130 μm and 222 μm and width of 8 μm were tested. The four-layer proposed structures with the outer diameter of 130 μm resulted in an inductance of 6.9 nH at 1 GHz with a peak quality factor of 6 at 2.1 GHz. In comparison, the inductor with the outer diameter of 222 μm has an inductance of 27 nH at 1 GHz with a peak quality factor of 3 at 1.1 GHz. The multilayer pyramidal symmetric inductor was implemented in the LC tank of a 2.4 GHz voltage controlled oscillator. The measured phase noise of the VCO is -99 dBc/Hz at 100 kHz and 108 dBc/Hz at 1 MHz offset frequency with a power consumption of 5 mW. The VCO was tuned with an inversion mode PMOS varactor and it operated from 2.441 to 2.557 GHz.

  2. Chip 2

    Name of the chip - IndiaChip-Analog 3
    Participating Institutes: Jadavpur University, Kolkata and IIT Guwahati
    Chip Integrator: IIT Guwahati
    Technical specification (Designs from IIT Guwahati)– 0.5 V 480 nW preamplifier, CMOS low power Precision temperature sensor, Inductive coupled Interchip transceiver
    Foundary - UMC L180 1P6M MM/RFCMOS process of United Microelectronics Corporation (UMC) through the mini@sic programme of Europractice IC Service.
    Silicon area -1525μm×1525μm

Device Developments:

  1. Device 1

    Name of the device: Carbon Nanotube Field-Effect Transistors (CNFETs)
    Name of Sponsor: Indian Nanoelectronics User Program (INUP) at Center of Excellence in nanoelectronics (CEN) Indian Institute of Technology Bombay, India
    Investigators: K.C. Narasimhamurthy and Roy Paily
    Duration: 12-01-2010 to 21-04-2010
    Device Details: Deposition of thin-film of SWCNT on the Hafnium oxide and SiO2 layers and achieved a good nanotube density. Fabricated semiconducting carbon nanotube thin-film transistors (SN-TFT) of channel dimensions from 2 µm to 500 µm. SN-TFTs of various gate structures like the global back gate, local back gate, top gate and dual gate are fabricated. The SN-TFTs have exhibited excellent p-type output characteristics for various gate voltages. The devices have shown good subthreshold slope, on-off current ratio, transconductance and carrier mobility.

  2. Device 2

    Name of the device: High Aspect Ratio Structures Fabricated over SAW Resonator
    Name of Sponsor: Indian Nanoelectronics User's Programme, Centre for Nano Science and Engineering (CeNSE), Indian Institute of Science (IISc), Bangalore, India
    Investigators: N. Ramakrishnan, Harshal B. Nemade and Roy Paily Palathinkal
    Year: 2010
    Device Details: More than 150 SAW resonators were fabricated in three 4 inch lithium niobate wafers. SU-8 pillar structures were fabricated over the SAW patterns to study the mass loading characteristics of high aspect ratio structures. Recipe to fabricate high aspect ratio SU-8 structures on lithium niobate were identified during the project. The resonance frequency of each resonator with and without pillars was measured and the dimensions of the pillars were recorded using optical microscope and SEM.

  3. Device 3

    Name of the device: Microhotplates for Gas Sensing Application
    Name of Sponsor: Indian Nanoelectronics User Program (INUP) at Center of Excellence in nanoelectronics (CEN) Indian Institute of Technology Bombay, India
    Investigators: Gaurav Saxena and Roy Paily
    Duration: January 2014 - May 2015
    Device Details: The design was carried out at IIT Guwahati and the fabrication was carried out through the Indian Nano User Program (INUP) at Center of Excellence in Nanoelectronics (CEN) at Indian Institute of Technology Bombay (IIT-Bombay). The microheater is patterned over a composite membrane consisting of Si/SiO2/Si3N4 layers. The performance of microhotplate was enhanced by the optimization of insulation layer area, especially for power and temperature uniformity aspects. An analytical model is developed for the optimization of the insulation nitride area and to determine microhotplates temperature profile and power consumption. The modular nature of the developed model, the thermal losses in the insulation layer were estimated separately. The strength of proposed device lies in its simplicity and cost effectiveness, as this it will not add any new process step to the existing fabrication flow. Bulk micromachining of silicon was carried out to define the thin stack. The fabricated microhotplate has an S-shape heater with an active area of 500um x 330um. In order to minimize the fabrication cost, plastic photomasks are employed for pattern transfer using lithography. Hence, the minimum lithographic dimension used in the microheater design is 50 um. After the wafer-level fabrication of microhotplate, individual devices are diced and electrical contacts were made using conductive silver epoxy paste. The microheater die is mounted hole is drilled into the PCB to alleviate the direct thermal losses to the PCB. For the temperature measurement, K-type thermocouples are used and their outputs are feed to an AD595 instrumentation amplifier IC that has provision for cold junction compensation. The analog output of AD595 is connected to a Data Acquisition (DAQ) board which has a 10 bit ADC resolution. A visual basic based program is used to control and acquire the data from the DAQ board. In addition, the TC523A temperature controller is used to monitor the temperature inside the testing box. HP E3631A DC power supply is used for supplying the current/voltage to the microhotplate. With 10 V applied, the current drawn is 38 mA and a maximum temperature of 393 K is observed, just before the epoxy contact failure. Using an alternate direct probing method, a temperature greater than 694 K is obtained when a current of 175 mA is applied. The heating efficiency of the present microhotplate is 1.85 10E(–6) W/um2.

    Device 4

    Name of the device: PIN Photodiodes with Low Dark current for Scintillation Detection
    Name of Sponsor: Defense Research and Development Organization, Hyderabad, India
    Investigators: Dr. Amitava DasGupta, Professor, EE Dept., IIT Madras
    Duration: Defense Research and Development Organization, Hyderabad, India
    Device Details: Worked as a Senior Project Officer from 07-04-1999 till the completion of the project. The responsibilities include the design of the wafer, design and development of the mask for PIN Photodiodes and fabrication of the PIN diodes with the low dark current. After successful completion of the project, complete process documents and packaged PIN diodes suitable for scintillation detection were delivered to DRDL.

    Device 5

    Name of the device: Silicon PIN Photodiodes for Detecting He-Ne Laser Signal
    Name of Sponsor: ELOIRA, RCA, Hyderabad
    Investigators: Dr. Amitava DasGupta, Professor, EE Dept., IIT Madras
    Duration: 09-07-2001 to 31-05-2003
    Device Details: Worked as a Project Officer for the project. The responsibilities include the design of the wafer, design and development of the mask for PIN Photodiodes and fabrication of the PIN diodes with the low dark current. The specifications were Dark current: < 1 nA at 12 V reverse bias, Responsivity: 0.40 A/W at 623 nm wavelength for devices with dimensions of 100 µm width and 60 µm separations. After successful completion of the project, complete process documents and packaged PIN diodes suitable for scintillation detection were delivered to ELOIRA.

    Device 6

    Name of the device: Indigenous Development of Si PIN Photodiodes
    Name of Sponsor: IISU, Indian Space Research Organization, Trivandrum, India
    Investigators: Dr. Amitava DasGupta, Professor, EE Dept., IIT Madras
    Duration: 16-04-2003 to 15-04-2004
    Device Details: Worked as a Project Officer for the project. The responsibilities include the design of the wafer, design and development of the mask for PIN Photodiodes and fabrication of the PIN diodes with the low dark current. The specifications were Dark current: < 1 nA at 5 V reverse bias, Responsivity: 0.40 A/W at 623 nm wavelength for devices with dimensions of 200 µm width and 60 µm separations. The initial fabrication and packaging of devices were successfully completed.

Sensor Developments:

  1. Sensor 1

    Name of the device: Glucose Sensor Based on Osmosis Principle without any chemical reaction
    Name of Sponsor: Indian Nanoelectronics User's Programme, Centre for Nano Science and Engineering (CeNSE), Indian Institute of Science (IISc), Bangalore, India
    Investigators: Nagesg CH and Roy Paily Palathinkal
    Duration: January 2012- May 2013
    Sensor Details: Few Sensors based on the principle of osmosis were designed and fabricated for glucose sensing applications. The design, packaging and testing was completed at IIT Guwahati while the fabrication of devices were carried out IISc. The advantages of sensors are their chemical-free nature, better response time, improved lifetime and absence of any mechanical excitations. The device was tested with different glucose concentrations ranging from 50 mg/dL to 450 mg/dL and the output voltage of the glucose sensor was increased from -6.7 mV to 22.4 mV.

  2. Sensor 2

    Name of the device: Field Effect Transistor Based Biosensor for Detection of Glutathione
    Name of Sponsor: Ministry of Electronics and Information Technology (Government of India) and EEE Department, Indian Institute of Technology Guwahati, India. The entire work was carried out at Centre for Nanotechnology, Indian Institute of Technology Guwahati, India
    Investigators: Ujjwol Barman, Roy Paily, Siddhartha Sankar Ghosh, Department of Biosciences and Bioengineering
    Duration: January 2018 - April 2019
    Sensor Details: This work involves the design and fabrication of a biosensor for the detection of glutathione, a biomarker for cancer. The experiments include the development of an effective functionalization mechanism on ZnO nanoparticles; followed by characterization tests on fabricated chemi-resistive and FET structures for successful detection of glutathione. Sensitivity and LOD obtained were ~60 uA/dec change in concentration and ~13 nM respectively with a linear response for 100 nM - 100 mM concentration of glutathione when the device was tested for glutathione as the solution. On the other hand, when characterized with cancer cells, ~200 nA/cell of sensitivity and LOD of ~30 cells were obtained. The assay time was less than a minute. This work is expected to have a potential impact in the field of cancer applications to detect the elevated concentration of glutathione.

    Sensor 3

    Name of the device: A Surface Acoustic Wave based biosensor for the Detection of Hepatitis B Surface Antigen
    Name of Sponsor: Ministry of Electronics and Information Technology (Government of India) and EEE Department, Indian Institute of Technology Guwahati, India. The work was carried out at Centre for Nanotechnology, Indian Institute of Technology Guwahati, India
    Investigators: Namami Goswami and Roy Paily, Siddhartha Sankar Ghosh, Department of Biosciences and Bioengineering
    Duration: January 2016 - December 2019
    Sensor Details: This work involves the design, simulation, fabrication and testing of a biosensor for the detection of Hepatitis B Surface Antigen. The device is a Surface Acoustic Wave (SAW) based dual delay line configuration, with one delay line used for the measurement of sample and the other for reference. The space between the input and output electrodes is used as the sensing area. Devices with three different interdigitated electrode widths are fabricated on two different piezoelectric substrates. A recombinant antibody used for the capture of the target biomolecule, Hepatitis B Surface Antigen is produced. The immobilization of the antibody to the sensing surface is achieved using the linker molecule 11-MUA. The novel concept of regeneration of the sensing area with acetate buffer is achieved for the first time. The device successfully and selectively functions in liquid medium detection. Also, a comparison has been made among the six devices, and a label-free detection method has been proposed. Out of the six devices, the highest frequency change of 889 kHz, and hence the best sensitivity was shown by the delay line with an IDT width of 4 um and 41° YX LiNbO3 substrate. The sensor showed a response to HBsAg in a range of 0.0818 IU/ml to 818000 IU/ml. The developed SAW immuno-biosensors showed a limit of detection of approximately 1.5 IU/ml. This work is expected to have a potential impact in the field of biosensing applications.

FPGA/Microcontroller/IoT based Developments:

  1. Project 1

    Name of the device: High-Throughput Turbo Decoder for Wireless Communication Systems
    Name of Sponsor: EEE Department, Indian Institute of Technology Guwahati, India
    Investigators: Rahul Shrestha and Roy Paily Palathinkal
    Duration: 2013 January -2014 April
    Project Details: The turbo decoder has eight parallel MAP cores and the target board was ALTERA Cyclone V SoC 5CSXFC6D6F31C8ES device. It has decoded 6144 bits in 5.5 iterations with a code-rate of 1/3. JTAG ports are used for the communication between FPGA and PC with a virtual logic analyzer. The input a-priori LLR soft-values were stored using onboard memories and were fed to the decoder which could operate at an operating frequency of 800 MHz. In order to capture the output waveform of 11 bits a-posteriori LLR value, the FPGA board was interfaced with a logic analyzer via HSMC which transfers data at a maximum rate of 3.125 Gbps. The values displayed on the logic analyzer screen were verified with the simulated results from the MATLAB environment. Thereafter, the BER plots of the hardware prototype of a parallel turbo decoder were compared with the simulated BER curve of turbo decoder. It showed that the implemented turbo decoder had degradation of 0.6 dB in comparison with the simulated BER value at 10E(-4) for eight decoding iterations.

  2. Project 2

    Name of the device: Micro-Cantilever Printing Based Devices and Applications
    Name of Sponsor: Centre for Nanotechnology and EEE Department, Indian Institute of Technology Guwahati, India
    Investigators: Vimal Kumar Singh Yadav and Roy Paily Palathinkal
    Duration: January 2018 - December 2019
    Project Details: Using Micro-Cantilever based Printing technology, micro-resistors, micro-Schottky diodes and field-effect transistors were fabricated. The print resolution and minimum feature size were in um. These resistors were cheaper compared to SMD chip resistors available in the market due to lower fabrication costs. The fabricated Schottky micro-diodes were tested as sensors for air pollutant gases such as CO2, CO and NO2 at room temperatures with a gas concentration ranging from ppb to ppm. The best sensitivity obtained was less than 1 ppb, a response time of few seconds and a recovery time of couple of minutes.

    System Developments:

    1. System 1

      Name of the device: Blind Assistance system using FPGAs and Sensors
      Name of Sponsor: Ministry of Electronics and Information Technology (Government of India) and EEE Department, Indian Institute of Technology Guwahati, India
      Investigators: Debajit Basak, Pralay Chakraborty, Siddhanta Roy, Nishanth PV, Monalisa Das, Satyajit Bora, Shruti Konwar, Amit Barman, Dipankar Talukdar, Jyotishman Saikia, Josephine Sylvester, Harshal Nemade and Roy Paily
      Duration: February 2011 - December 2016
      System Details: In this project, a low-cost, user-friendly, and portable system has been developed to assist the navigation of the visually impaired. The proposed blind assistance system detects the obstacles present on the path of navigation of the visually impaired, by using a stereo pair of cameras. The distance towards the detected obstacle is estimated by using the triangulation method which exploits the stereo correspondence of different points on the scene captured by the cameras. The correspondence between pixels from a given stereo pair of images is computed by using the ZSAD (Zero Mean Sum of Squared Differences) algorithm. The proposed system also includes an object recognition module which can recognize the presence of human and car among the detected obstacles. Object recognition is achieved through the parallel implementation of two independent binary SVM classifiers utilizing HOG (Histograms of Oriented Gradients) features extracted from the images. The navigation of the visually impaired is guided by informing the details about the detected obstacles through a series of audio messages. A prototype of the proposed blind assistance system has been implemented on a hardware platform based on Xilinx FPGA. The architecture utilizes 31453 FFs, 25883 LUTs, 1206 Memory LUTs, 131.5 BRAMs, 17 DSP48s, 8 BUFGs and 1 MMCM. Typically, performance in object detection systems is measured in frames per second. The proposed architecture works up to clock frequency of 150MHz. The disparity estimation has an initial latency of 20.81ms and that of SVM is 22.53ms. So, the overall latency of the system is 22.53ms which is due to SVM. It works at a frame rate of 4.02fps at 150MHz. It is found that human and car detection accuracy is about 90%. The total power consumed of the entire system was within 2.5W. The functionality of the hardware prototype has been evaluated through several experiments conducted under different real-time, real-world scenarios such as indoor environment, outdoor environment, parking lot, etc. These experiments have revealed that the prototype system delivers expected results under different scenarios, thereby proving its acceptability as a blind assistance system. Based on the observation that the objectives of a blind assistance system and collision avoidance system used in vehicle parking are closely related, a standalone anti-collision system for preventing collisions in a parking lot has also been implemented by using an array of ultrasonic sensors and Arduino embedded platform.

    2. System 2

      Name of the device: An FPGA /ASIC Based Sensor Platform for Monitoring Air Pollutants
      Name of Sponsor: Ministry of Electronics and Information Technology (Government of India) and EEE Department, Indian Institute of Technology Guwahati, India
      Investigators: Hari Sarkar, Deep Jyoti Das, Thockchom Birjir Singha, Shruti Konwar, Amit Barman, Gagan Deep Singh, Sandeep P., Thomas Daniel, Vimal Kumar Singh Yadav, Josephine Sylvester, Nallam Nagarjuna and Roy Paily
      Duration: December 2014 - November 2020
      Project Details: The aim of this project is to develop a low-cost, portable sensor platform to measure air pollutants. The proposed system is developed to monitor the concentration of pollutant gases such as CO, CO2 and NO2, along with temperature and relative humidity of a localized area of 100 squre meter. The system is intended to be deployed in various parts of the North-Eastern India. The Air Quality Monitoring System (AQMS) is targeted for a sensitivity of < 1 mV, a power consumption of < 1W operating with a power bank with a capacity of 11000 mAh with a supply voltage < 5 V and the physical dimensions within 20cm x 20 cm x 15 cm. The individual components such as five sensors, amplifier, ADC, multiplexer, processor, external memory, display and RF module, and their specifications were finalized in the initial phase after relevant discussions. LM35 was selected as the Temperature Sensor, HiH 5030 as the Humidity Sensor, NDIR MH-Z14 as the CO2 Sensor and MiCS-4514 as the CO/NO2 Sensor. A 10-bit ADC with a resolution of 5 mV is used for converting the analog signal to digital bits. An Atmega-based processor embedded in an Arduino module was used for processing and controlling the whole system. A time division multiplexing (TDM) unit, memory and an RF module is attached to the processor. The TDM module allows only a single sensor data to be transmitted at a time. As the sensor data is not sought 24×7, rather each sensor data is read once every hour sequentially, a power control management unit is used to turned OFF the unused sensors as well as other blocks to save power. In order to reduce the transmission power, the data is temporarily stored in MicroSD module before its transmission. For the data display and for date/time stamp an LCD screen and RTC is used. An amplifier IC is specifically designed for this work. The design incorporates a 10-input Op-Amp, along with switch select pins for multiplexing the desired sensor data. The desired gain values and filtering are achieved by feedback for each sensor by controlling switches. The targeted values of amplifier are a supply voltage of 3.3 V, Input Common-mode Range (ICMR) from 0.3 V to 3 V, Output swing from 0.3 V to 3 V, output C = 10 pF which is the input capacitance of the ADC, a GBW > 2 MHz, Gain > 60 dB, PM > 45° and Power consumption < 2 mW. This amplifier was taped out with TSMC 180nm technology devices and the measured results have demonstrated that they were well within in the target specifications. A stacked board with three PCBs and a power bank were enclosed in a package that ensures the entry of atmospheric gases while restricting the water in case of rain. Testing of the complete board is done under different humidity, temperature environments and data has been collected. Using an indigenously developed facility at IIT Guwahati, we have completed the calibration of NO2, CO2 and CO gases. Custom made waterproof enclosure meeting standard IP67 is in progress.