Sambuddha Khan

Tyndall National Institute, Micro-Nano Systems, Senior Scientist II

Jadavpur University, Kolkata, India, School of BioScience and Engineering, Alumnus

Indian Institute of Science, CEDT, Graduate Student

Indian Institute of Science, Center for Nano Science and Engineering, Graduate Student

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I am currently employed in University of California, Irvine as an Assistant Specialist in the Department of Mechanical and Aerospace Engineering. My work is being supervised by Prof. Andrei Shkel. I have completed PhD in Nano Engineering for Integrated Systems (NIS) in Centre for Electronics Design and Technology (CEDT) and Department of Mechanical Engineering (ME), Indian Institute of Science (IISc), Bangalore.
Supervisors: Prof. Andrei Shkel, Prof. G. K. Ananthasuresh, and Prof. H. S. Jamadagni
Phone: (949)247-1641
Address: Microsystem Lab, Department of Mechanical and Aerospace Engineering, University of California, Irvine, CA, USA, 92697

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Papers by Sambuddha Khan

A Study on a Tether-Less Approach Towards Micro-Transfer-Printing of Large-Footprint Power Micro-Inductor Chiplets

2023 IEEE International 3D Systems Integration Conference (3DIC)

A Micromachined Wide-Band In-Plane Single-Axis Capacitive Accelerometer with a Displacement-Amplifying Compliant Mechanism

Mechanics Based Design of Structures and Machines, 2014

ABSTRACT With the premise that electronic noise dominates mechanical noise in micromachined accel... more ABSTRACT With the premise that electronic noise dominates mechanical noise in micromachined accelerometers, we present here a method to enhance the sensitivity and resolution at kHz bandwidth using mechanical amplification. This is achieved by means of a Displacement-amplifying Compliant Mechanism (DaCM) that is appended to the usual sensing element comprising a proof-mass and a suspension. Differential comb-drive arrangement is used for capacitive-sensing. The DaCM is designed to match the stiffness of the suspension so that there is substantial net amplification without compromising the bandwidth. A spring-mass-lever model is used to estimate the lumped parameters of the system. A DaCM-aided accelerometer and another without a DaCM—both occupying the same footprint—are compared to show that the former gives enhanced sensitivity: 8.7 nm/g vs. 1.4 nm/g displacement at the sensing-combs under static conditions. A prototype of the DaCM-aided micromachined acclerometer was fabricated using bulk-micromachining. It was tested at the die-level and then packaged on a printed circuit board with an off-the-shelf integrated chip for measuring change in capacitance. Under dynamic conditions, the measured amplification factor at the output of the DaCM was observed to be about 11 times larger than the displacement of the proof-mass and thus validating the concept of enhancing the sensitivity of accelerometers using mechanical amplifiers. The measured first in-plane natural frequency of the fabricated accelerometer was 6.25 kHz. The packaged accelerometer with the DaCM was measured to have 26.7 mV/g sensitivity at 40 Hz.

High Resolution Inertial Sensors

Dynamic Characterization of a Fabricated Dual-axis In-plane Capacitive Accelerometer for High-frequency Applications

Compact in-plane dual-axis spring-steel accelerometer

Presented in this paper is an improvement over a spring-steel dual-axis accelerometer that we had... more Presented in this paper is an improvement over a spring-steel dual-axis accelerometer that we had reported earlier.The fabrication process (which entails wire-cut electro discharge machining of easily accessible and inexpensive spring-steelfoil) and the sensing of the displacement (which is done using off-the-shelf Hall-effect sensors) remain the same. Theimprovements reported here are twofold: (i) the footprint of the packaged accelerometer is reduced from 80 mm square to 40mm square, and (ii) almost perfect de-coupling and symmetry are achieved between the two in-plane axes of the packageddevice as opposed to the previous embodiment where this was not the case. Good linearity with about 40 mV/g was measuredalong both the in-plane axes over a range of 0.1 to 1 g. The first two natural frequencies of the devices are at 30 Hz and 100Hz, respectively, as per the experiment. The highlights of this work are cost-effective processing, easy integration of the Hall-effect sensing capability on a customised printed circuit board, and inexpensive packaging without overly compromising eitherthe overall size or the sensitivity of the accelerometer. Through this work, we have reaffirmed the practicability of spring-steelaccelerometers towards the eventual goal of making it compete with micro machined silicon accelerometers in terms of sizeand performance. The cost is likely to be much lower for the spring-steel accelerometers than that of silicon accelerometers, especially when the volume of production is low and the sensor is to be used as a single packaged unit.

Improving the Sensitivity and Bandwidth of In-Plane Capacitive Microaccelerometers Using Compliant Mechanical Amplifiers

Journal of Microelectromechanical Systems, 2014

ABSTRACT This paper presents a method to enhance both the sensitivity and bandwidth of in-plane c... more ABSTRACT This paper presents a method to enhance both the sensitivity and bandwidth of in-plane capacitive micromachined accelerometers by using compliant mechanical amplifiers, and thus obviating the compromise between the sensitivity and bandwidth. Here, we compare one of the most sensitive single-axis capacitive accelerometers and another with large resonant frequency reported in the literature with the modified designs that include displacement-amplifying compliant mechanisms (DaCMs) occupying the same footprint and under identical conditions. We show that 62% improvement in sensitivity and 34% improvement in bandwidth in the former, and 27% and 25% in the latter can be achieved. Also presented here is a dualaxis accelerometer that uses a suspension that decouples and amplifies the displacements along the two in-plane orthogonal axes. The new design was microfabricated, packaged, and tested. The device is 25-μm thick with the interfinger gap as large as 4 μm. Despite the simplicity of the microfabrication process, the measured axial sensitivity (static) of about 0.58 V/g for both the axes was achieved with a cross-axis sensitivity of less than ±2%. The measured natural frequency along the two in-plane axes was 920 Hz. Displacement amplification of 6.2 was obtained using the DaCMs in the dual-axis accelerometer.

A micro-mechanical compliant device for individual cell-stretching, compression, and in-situ force-measurement

2017 International Conference on Manipulation, Automation and Robotics at Small Scales (MARSS), 2017

(We describe the fabrication, characterization and operation of a microfabricated, overhanging mi... more (We describe the fabrication, characterization and operation of a microfabricated, overhanging micromachined SU-8 device that can stretch and compress individual cells. This compliant device is composed of folded beams with a single actuation point. Upon actuation with a glass micropipette attached to an XYZ positioner, it can apply varying deformation to multiple cells simultaneously. The applied force is computed using the measured displacement of the compliant device. Cell-attachment is achieved by simply adding a suspension of cells on the device. The stiffness of the device was designed such that cells can deform the beams they are attached to. Measuring this deformation in the absence of actuation allows for quantifying the forces exerted by the cells with a resolution of 0.18 μΝ.)

Micromachined Accelerometers with Mechanical Amplification

Development Of Micromachined And Meso-Scale Multi-Axis Accelerometers With Displacement-Amplifying Compliant Mechanisms

Development of micromachined and meso-scale

Wireless sensor networks for human intruder detection

| In this paper we report on the outcomes of a research and demonstration project on human intrus... more | In this paper we report on the outcomes of a research and demonstration project on human intrusion detection in a large secure space using an ad hoc wireless sensor network. This project has been a unique experience in collaborative research, involving ten investigators (with expertise in areas such as sensors, circuits, computer systems, communication and networking, signal processing and security) to execute a large funded project that spanned three to four years. In this paper we report on the specific engineering solution that was developed: the various architectural choices and the associated specific designs. In addition to developing a demonstrable system, the various problems that arose have given rise to a large amount of basic research in areas such as geographical packet routing, distributed statistical detection, sensors and associated circuits, a low power adaptive micro-radio, and power optimising embedded systems software. We provide an overview of the research results obtained. aSmartDetect is a research and demonstration project funded by the ER&IPR Division of the Defence Research and Development Organisation (DRDO), Government of India, during the period 2006-2010. The following project team contributed to the work presented in this paper: Anurag Kumar (Principal Investigator), P. Vijay Kumar (co-Principal Investigator); (the following are in alphabetical order within category) Faculty Investigators: Bharadwaj Amrutur, G.K. Ananthasuresh, Navakanta Bhat, R.C. Hansdah, Malati Hegde, Joy Kuri, Vinod Sharma, Y.N. Srikant, Rajesh Sundaresan; Project Staff: Tarun Agarwal, S.V.R. Anand, Pallav Bose, Vijay Dewangan, Shalini Keshavamurthy, A.V. Krishna, Pavan Kumar, Sharath Kumar, D. Manjunath, Sundeep Patil, Poornima V.L., K. Aditya Prasad, Santosh Ramachandran, Anurag Ranjan, Subathra Sampath, Jeena Sebastian, Vishwas Vasuki; Students: Pranav Agrawal, Sahebrao Sidram Baiger, Vinod Kumar Chouhan, Taposh Banerjee, Satyam Dwivedi, Abhishek Gupta, Santosh Hedge, Neeraj Kumar, Prachee Jindal, Premkumar Karumbu, Sambuddha Khan, Girish Krishnan, Syam Krishnan, Chaitanya U. Kshirasagar, K.P. Naveen, Mohan Rathod, Deepak Ravi, U. Raviteja, R. Abu Sajana, Ramanathan Subramanian, Thejas, Amulya Ratna Swain, Lalitha Vadlamani, Leena Zacharias.

Development of a Meso-scale Dual-axis Steel Accelerometer with Hall-effect Sensors

We present here an overview of the work done on the development of a mesoscale dual-axis spring s... more We present here an overview of the work done on the development of a mesoscale dual-axis spring steel in-plane accelerometer equipped with Hall-effect sensors. The design of the accelerometer has the unique feature that there is perfect de-coupling of the motions in the two in-plane orthogonal directions. One more extra feature is the use of rechargeable Li-ion batteries as a part of the proof-mass in addition to serving as the power source. The mechanical element of the accelerometer is made of EN J42/AISI 1080 spring steel foil machined using Wirecut Electro-Discharge Machining (EDM) process. Allegro A1395 linear Hall-effect sensors are used to transduce the displacement of the proof-mass into voltage. The packaged sensor has an overall dimension of 73 mm × 73 mm × 28.5 mm. The packaged sensor can detect an acceleration signal as small as 25 milli-g with a measured sensitivity of 78 mV/g and 102 mV/g along X and Y axes respectively. Reason for asymmetry and scope for improvement in performance, reduction in size, and batch production are also discussed in this paper.

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Mode ordering in tuning fork structures with negative structural coupling for mitigation of common-mode g-sensitivity

2015 IEEE SENSORS, 2015

Sensitivity Enhancement of a Dual-axis In-plane Capacitive Micro-accelerometer using Compliant Displacement-amplifiers

Improving the Sensitivity and Bandwidth of In-Plane Capacitive Microaccelerometers Using Compliant Mechanical Amplifiers

This paper presents a method to enhance both the sensitivity and bandwidth of in-plane capacitive... more This paper presents a method to enhance both the sensitivity and bandwidth of in-plane capacitive micromachined accelerometers by using compliant mechanical amplifiers, and thus obviating the compromise between the sensitivity and bandwidth. Here, we compare one of the most sensitive single-axis capacitive accelerometers and another with large resonant frequency reported in the literature with the modified designs that include displacement-amplifying compliant mechanisms (DaCMs) occupying the same footprint and under identical conditions. We show that 62% improvement in sensitivity and 34% improvement in bandwidth in the former, and 27% and 25% in the latter can be achieved. Also presented here is a dualaxis accelerometer that uses a suspension that decouples and amplifies the displacements along the two in-plane orthogonal axes. The new design was microfabricated, packaged, and tested. The device is 25-μm thick with the interfinger gap as large as 4 μm. Despite the simplicity of the microfabrication process, the measured axial sensitivity (static) of about 0.58 V/g for both the axes was achieved with a cross-axis sensitivity of less than ±2%. The measured natural frequency along the two in-plane axes was 920 Hz. Displacement amplification of 6.2 was obtained using the DaCMs in the dual-axis accelerometer.

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A Micromachined Wide-Band In-Plane Single-Axis Capacitive Accelerometer with a Displacement-Amplifying Compliant Mechanism

DOI: 10.1080/15397734.2014.908299, May 20, 2014

With the premise that electronic noise dominates mechanical noise in micromachined accelerometers... more With the premise that electronic noise dominates mechanical noise in micromachined accelerometers, we present here a method to enhance the sensitivity and resolution at kHz bandwidth using mechanical amplification. This is achieved by means of a Displacement-amplifying Compliant Mechanism (DaCM) that is appended to the usual sensing element comprising a proof-mass and a suspension. Differential comb-drive arrangement is used for capacitive-sensing. The DaCM is designed to match the stiffness of the suspension so that there is substantial net amplification without compromising the bandwidth. A spring-mass-lever model is used to estimate the lumped parameters of the system. A DaCM-aided accelerometer and another without a DaCM—both occupying the same footprint—are compared to show that the former gives enhanced sensitivity: 8.7 nm/g vs. 1.4 nm/g displacement at the sensing-combs under static conditions. A prototype of the DaCM-aided micromachined acclerometer was fabricated using bulk-micromachining. It was tested at the die-level and then packaged on a printed circuit board with an off-the-shelf integrated chip for measuring change in capacitance. Under dynamic conditions, the measured amplification factor at the output of the DaCM was observed to be about 11 times larger than the displacement of the proof-mass and thus validating the concept of enhancing the sensitivity of accelerometers using mechanical amplifiers. The measured first in-plane natural frequency of the fabricated accelerometer was 6.25 kHz. The packaged accelerometer with the DaCM was measured to have 26.7 mV/g sensitivity at 40 Hz.

Wireless Sensor Networks for Human Intruder Detection

Journal of the Indian Institute of Science, VOL 90:3, Sep 1, 2010

In this paper we report on the outcomes of a research and demonstration project on human intrusio... more In this paper we report on the outcomes of a research and demonstration project on human intrusion detection in a large secure space using an ad hoc wireless sensor network. This project has been a unique experience in collaborative research, involving ten
investigators (with expertise in areas such as sensors, circuits, computer systems, communication and networking, signal processing and security) to execute a large funded project that spanned three to four years. In this paper we report on the specific engineering
solution that was developed: the various architectural choices and the associated specific designs. In addition to developing a demonstrable system, the various problems that arose have given rise to a large amount of basic research in areas such as geographical packet routing, distributed statistical detection, sensors and associated circuits, a low power adaptive micro-radio, and power optimising embedded systems software. We provide an overview of the research results obtained.

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Micromachined Accelerometers with Mechanical Amplification.

International Conference on Microactuators and Micromechanisms (MAMM-2012)

Dynamic Characterization of a Fabricated Dual-axis In-plane Capacitive Accelerometer for High-frequency Applications.

International Conference on Smart Materials Structures and Systems (ISSS-2012)

This paper presents dynamic characterization of a micromachined in-plane capacitive dual-axis acc... more This paper presents dynamic characterization of a micromachined in-plane capacitive dual-axis accelerometer with wide operational 3 dB bandwidth and low cross-axis sensitivity. The mechanical sensing element consists of a proof-mass and 12 compliant folded beam suspensions arranged in a special way to achieve perfect de-coupling of in-plane motions of the proof-mass along two orthogonal axes and with high rotational stiffness. The two axes of the accelerometer are functionally de-coupled from each other but they share a common proof-mass. De-coupling mechanism ensures low cross-axis sensitivity. Furthermore, sense-combs are attached to the compliant de-coupling mechanism to capture the change in capacitance due to the displacement of the proof-mass. The device was fabricated using Silicon-on-Insulator Multi-user MEMS Processes (SOIMUMPs). As per simulation, the device has a 3 dB bandwidth of 8.27 kHz and 0.5 fF/g capacitive sensitivity. Die-level dynamic characterization using laser Doppler vibrometer showed that its bandwidth is approximately 8.5 kHz. The quality factor of the response was found to be about 26 in ambient pressure. The damping ratio was determined to be 0.023 as calculated experimentally using the step-response of the accelerometer.

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High Resolution Inertial Sensors

by Sambuddha Khan and Rudra Pratap

Student Research Preview at International Solid-State Circuits Conference (ISSCC), Feb 2010