SUNFEST at Penn
2014 Sample Projects
Descriptions of sample projects are given below. Use these to select which project you would like to work on. All the projects are related to the general area of sensor technologies, which acts as a common, intellectual focus.
Once you have been admitted to the program, it is recommended that you contact the faculty member for additional information on any of these or other projects. Feel free to make arrangements with the faculty member prior to starting the SUNFEST program.
Professor Haim H. Bau, Mechanical Engineering and Applied Mechanics
Since its invention, the electron microscope has facilitated numerous advances in diverse disciplines. The electron microscope provides sub-nanometer resolution, which far surpasses the resolution of conventional light microscopy. Traditional electron microscopy must be carried out, however, in a high vacuum environment that does not allow for real time imaging of processes in liquids. The traditional electron microscope imaging technology is often restricted to “postmortem,” after the fact investigations of dry or frozen samples. This is a slow, painstaking procedure that requires one to fix or freeze the sample at various stages of the process and prepare it for imaging without any guarantee that an image is captured at the “right” moment. Static images also do not provide information on process dynamics, and the sample preparation for electron microscope imaging may adversely impact the structure of the object to be imaged. For example, the ability to image structural and conformational changes of individual molecules under physiological conditions (in liquids) is certain to be transformative, lead to new discoveries, and provide a better understanding of important nanoscale processes.
The Bau group, who has a tradition of involving undergraduate students in the research, has developed the nanoaquarium that allows one to image processes in liquids with the high resolution of the electron microscope. The nanoaquarium consists of a thin liquid layer (tens to hundreds of nanometers in thickness) sandwiched between two electron transparent silicon nitride membranes. The liquid in the nanoaquarium is sealed from the vacuum of the electron microscope . The nanoaquarium is thin enough to allow electrons to go through with minimal inelastic scattering by the liquid, providing nm resolution. We have carried out a few experiments demonstrating the viability of this technology to study diffusion-limited aggregation, crystallization, dendrite formation during electrochemical processes, and bubble nucleation and growth  . The nanoaquarium is also useful to study and optimize processes taking place ion batteries and energy storage devices. This project will focus on both enhancing the nanoaquarium capabilities and using the nanoaquarium to gain new insights into various important processes.
The list below provides a sample of possible projects for undergraduate researchers.
- Equip the nanoaquarium with a heater for temperature control and studying boiling on patterned surfaces with the objective of optimizing heat transfer. The study is of relevance for improving temperature control in computer components and other types of equipment.
- Equip the nanoaquarium with on-board storage compartments for various fluids and develop means for pumping fluids to enable in-situ mixing and imaging of chemical interactions.
The participating student will be exposed to challenging, cutting edge research problems, to microfabrication, and electron microscopy.
-  J. M. Grogan and H. H. Bau, “A Nanoaquarium for in situ Electron Microscopy in Liquid Media,” pp. 1–2, 2010.
-  J. M. Grogan and H. H. Bau, “The Nanoaquarium: A Platform for Transmission Electron Microscopy in Liquid Media,” Journal of Microelectromechanical Systems, vol. 19, no. 4, pp. 885–894, Aug. 2010.
-  J. M. Grogan, L. Rotkina, and H. H. Bau, “In situ liquid-cell electron microscopy of colloid aggregation and growth dynamics,” Physical Review E, vol. 83, no. 6, p. 061405, Jun. 2011.
Professor Daeyeon Lee, Chemical and Biomolecular Engineering
The goal of this project is to develop environmentally benign colorimetric sensors that can detect the presence and concentration of analyte such as heavy metals, glucose and pathogens. We will use a microfluidic technique developed to generate photonic crystal spheres that changes their color in respond to the presence of an analyte in the solution. These colorimetric sensor spheres will be generated by encapsulating highly charged particles such as silica with a monomer (acrylamide), a crosslinker (bisacrylamide) and a photoinitiator in water-in-oil emulsion droplets. We have already successfully shown that UV irradiation of these droplets yields tunable colloidal crystals immobilized in soft hydrogels that has a strong diffraction peak in the visible range . We will functionalize the hydrogel with moieties that specifically interacts with our target analyte. The binding of the analyte with the hydrogel network of the photonic crystal spheres will induce changes in the interparticle spacing between silica particles and shift the Bragg diffraction, resulting in changes in the diffraction color.
The students involved in this program will directly learn how to prepare glass capillary microfluidic device using a capillary puller and a microforge. The student will also learn to model the Bragg diffraction of these photonic crystal spheres based on the diffraction theory. Each year, a student(s) will develop a new hydrogel network that will respond to different types of analyte. For example, to detect the presence of glucose, the student will functionalize the network with boronic acid. The student will learn both the theoretical and experimental aspects of photonic materials from this project. Our group has a strong history of mentoring undergraduate students (38 students since 2004) and has published over 10 papers with undergraduate researchers.
-  T. Kanai, D. Lee, H. C. Shum, R. K. Shah, and D. a Weitz, “Gel-immobilized colloidal crystal shell with enhanced thermal sensitivity at photonic wavelengths.,” Advanced materials (Deerfield Beach, Fla.), vol. 22, no. 44, pp. 4998–5002, Nov. 2010.
-  T. Kanai, D. Lee, H. C. Shum, and D. a Weitz, “Fabrication of tunable spherical colloidal crystals immobilized in soft hydrogels.,” Small (Weinheim an der Bergstrasse, Germany), vol. 6, no. 7, pp. 807–10, Apr. 2010.
Professor Shu Yang, Materials Science and Engineering
The increasing technological needs for a new generation of optical devices with novel architectures, tunability and tailored properties, provides a potent stimulus to the study and replication of optical systems in living organisms. In particular, we are interested in how the bio-organisms alter their appearance in response to environmental change, which in turn will allow us to design smart windows that can sense temperature and light intensity change. Here, we will create microstructured metamaterials in soft materials, which can reconfigure the shape and structure in response to external stimuli. By designing lattice symmetry and shape, and use of anisotropic materials, our goal is to induce dramatic volume change, thus, symmetry and optical property change at the cusps of instability of the periodic structures using as small as possible stress/strain. These will form the basis of novel sensors for environmental applications.
The student will work with senior graduate students and post-doctoral fellows in a team with diverse background, including materials science and engineering, electrical engineering, optical engineering. He/She will learn about polymer/colloidal particle formulation, design and microfabrication using photolithography, soft lithography techniques, sample characterization using SEM and AFM), (fluorescent) optical microscope measurements and basics of sensing phenomena.
Professor Jorge Santiago, Electrical and Systems Engineering
Hybrid super-capacitors are being considered as promising electrical energy storage devices in powering robotics and distributed sensors / actuators, as they might combine the high power density of a super-capacitor with the high energy density of a modern battery. For the electrical double layer (physical) part of the hybrid, we have been exploring the utilization of different high specific surface area carbonaceous materials, and for the Faradaic (redox or electrochemical) part of the hybrid, the utilization of the thiophene polymer PproDOT.
The students participating in this program will be preparing some of the materials from precursors, such as mixing and forming carbon / polymer composites and doing electro-polymerization for the formation of electrodes. They will perform electrochemical capacitors characterization to evaluate capacitance and equivalent series resistance. For these experiments, the students will be using Cyclic Voltammetry and electrochemical Impedance spectroscopy. The participants will benefit by learning the fundamentals of electrochemistry in the context of electrical energy storage, will familiarize with the electrochemical instrumentation, hybrid capacitors characterization and with simulation software. 
-  H. K. Sahoo, E. Villarreal, R. Cardona, and J. J. Santiago-Avilés, “Influence of Materials and Process Parameters on the Performance of Carbon based Super-capacitors,” J. of Power Sources, 2013.
Professor Rahul Mangharam, Electrical and Systems Engineering
Over the past five years, the Real-Time and Embedded Systems Lab at UPenn has been developing medical device software and systems. We now plan to develop a low-cost portable test-bed for physiological control systems. Such systems include automatic drug infusion pumps, say to deliver morphine to a patient recovering from a surgery. Our goal is to develop an Intensive Care Unit (ICU) in a bag to explore control algorithms for safe drug delivery. This will include patient simulators, supervisory control software for Programmable Logic Controllers, a selection of medical sensors such as wearable ECG patches, pulse oximeters, etc. and a network of actuating devices such as a low-cost infusion pump. The ICU-in-a-Bag will also mimic an operating room with multiple sensors and invite investigations for smart alarms to reduce alarm fatigue with nurses. The Sunfest REU student will have some background in bio-medical engineering and love to program embedded systems.
Professor Jan Van der Spiegel, Electrical and Systems Engineering
The development on microelectronics in the last two decades enables the neurologists to study neural activity in non-human primates (NHP) during free behavior by employing portable brain-computer interface (BCI) . The goal of the overall research program is to introduce various sensing devices into the traditional BCI system, as a Sensor-Brian-Computer-Interface (SBCI) system, to monitor and/or reconstruct somatosensory of human beings and/or various NHP. A traditional BCI system includes i) multi-electrode neural recording device ; ii) multi-electrode stimulating device  and iii) user friendly graphic interface on the computer.
Dr. Van der Spiegel, his post-docs and graduate students have built a general-purpose BCI system featuring multi-channel neural data recording/stimulating, wireless communication and real-time configuration. Our recent research aims to implement battery-free active smart sensory nodes enable the detection of temperature, pressure, skin deformation, etc., powered by energy harvesting from emitted radio waves. The proposed sensor node will be wirelessly detected and controlled by a wearable device which is part of the SBCI system. This work is in collaboration with Professor Tim Lucas of the School of Medicine and Professor Nader Engehta of the Electrical and Systems Engineering Dept.
REU students will be involved in i) sensor design and testing, ii) graphic user interface (GUI) design, iii) online/offline signal processing, e.g. spike detection, feature extraction, and iv) recorder-stimulator and/or sensor-stimulator modulation. The students will learn neurobiology, sensor design, wireless communication, biological signal processing and its engineering applications.
-  S. Zanos, A. G. Richardson, L. Shupe, F. P. Miles, and E. E. Fetz, “The Neurochip-2: an autonomous head-fixed computer for recording and stimulating in freely behaving monkeys.,” IEEE transactions on neural systems and rehabilitation engineering: a publication of the IEEE Engineering in Medicine and Biology Society, vol. 19, no. 4, pp. 427–35, Aug. 2011.
-  M. K. Awais and J. M. Andrew, “On-chip feature extraction for spike sorting in high density implantable neural recording systems,” 2010 Biomedical Circuits and Systems Conference (BioCAS), pp. 13–16, Nov. 2010.
-  S. Stanslaski, P. Afshar, P. Cong, J. Giftakis, P. Stypulkowski, D. Carlson, D. Linde, D. Ullestad, A.-T. Avestruz, and T. Denison, “Design and validation of a fully implantable, chronic, closed-loop neuromodulation device with concurrent sensing and stimulation.,” IEEE transactions on neural systems and rehabilitation engineering: a publication of the IEEE Engineering in Medicine and Biology Society, vol. 20, no. 4, pp. 410–21, Jul. 2012.
-  R. M. Walker, H. Gao, P. Nuyujukian, K. Makinwa, K. V Shenoy, T. Meng, and B. Murmann, “A 96-Channel Full Data Rate Direct Neural Interface in 0 . 13 µ m CMOS,” pp. 144–145, 2011.
Professor Vijay Kumar, Mechanical Engineering and Applied Mechanics
"Biological cells have many built-in mechanisms for sensing changes in the environment, and these sensing mechanisms may be modified, enhanced, and augmented using techniques from genetic engineering. Synthetically engineered cells sense and report changes in chemical concentration, light exposure and temperature. We are investigating methods for interfacing synthetic biological systems with non-living components, thereby creating microbiorobotic sensors. Our group develops microbiorobots with length scales on the order of 10-100 microns for manipulating cells and microfabricated structures. We have previously investigated methods for actuating such robots . These methods include using magnetic field gradients as well as harnessing the propulsive forces from swarms of bacterial cells. We are specifically interested in advancing the capabilities of magnetic microrobots by integrating bioengineered cellular sensors to detect changes in light or chemical concentration. The primary impact of this work will be the development of a suite of techniques for integrating abiotic microactuators with biological sensors, such that newly developed cells may be rapidly integrated and characterized with existing magnetic actuation systems. Our group has had many undergraduate students involved in the research. Some of the PhD students were former Sunfest REU fellows.
The students will learn how to develop and characterize microbiorobotic sensors while learning techniques for microfabrication, cell culture and microscopy while integrating project components. Students will also learn how to model and analyze experimental results under the guidance of post-doctoral fellows and graduate students.
-  E. B. Steager, M. Selman Sakar, C. Magee, M. Kennedy, a. Cowley, and V. Kumar, “Automated biomanipulation of single cells using magnetic microrobots,” The International Journal of Robotics Research, vol. 32, no. 3, pp. 346–359, Mar. 2013.
Professor Dan Koditschek, Electrical and Systems Engineering
As mobile robots leave the laboratory and begin interacting with real, unstructured terrain, body contact with the ground becomes inevitable and sometimes desirable to achieve certain highly energetic tasks . Various “electronic skins” and other tactile sensors have been proposed to sense pressure and contact at multiple locations on a robot's body. However these methods require a new, often soft layer of material be attached to the exterior of the robot and directly come into contact with the ground. Alternatively high-precision depth sensors can produce a 3D model of the ground in front of the robot, while careful state estimation can predict where the robot itself is and therefore where contact could be occurring. These exteroceptive methods are computationally intensive and not robust to changing ground conditions. Instead we are seeking a non-tactile body contact sensor that relies on measurements of body accelerations without changing the external material (in this case hard carbon fiber) used on the robot, similar to .
Students working on this project will integrate several small MEMS accelerometers and related circuitry into the robot's body. Then using various statistical learning techniques, derive a robust classifier to distinguish between the “expected” signal that occurs during walking and the “unexpected” signal from a collision , as well as possibly a triangulated location and magnitude of the contact event. In addition to these electronic circuit design, signal processing, and analysis skills, the student will also learn how the RHex-style  legged robots work and create reactive behaviors that use this new information.
-  A. M. Johnson and D. E. Koditschek, “Toward a Vocabulary of Legged Leaping,” pp. 2553–2560, 2013.
-  W. Mcmahan, J. M. Romano, and K. J. Kuchenbecker, “Using Accelerometers to Localize Tactile Contact Events on a Robot Arm [ Extended Abstract ].”
-  A. M. Johnson, G. C. Haynes, and D. E. Koditschek, “Disturbance Detection , Identification , and Recovery by Gait Transition in Legged Robots Recovery by Gait Transition in Legged Robots,” pp. 5347–5353, 2010.
-  U. Saranli, M. Buehler, and D. E. Koditschek, “RHex: A Simple and Highly Mobile Hexapod Robot RHex: A Simple Hexapod Robot,” 2001.
Professor C.J. Taylor, Computer and Information Science
The emergence of cheap RGB-D sensors like the Kinect has helped to revolutionize the field of robotics by making it simpler for robots to perceive their 3D environment. In this work we aim to leverage the capabilities of these sensors to develop new real-time motion planning algorithms that would allow humanoid robotic systems like the Willow Garage PR2 to interact safely in complex environments populated with human actors. This work will build upon free-space representations of the workspace that can be derived directly from the RGB-D sensor data and high performance planning systems.
Students involved in the project will become familiar Kinect, use it for motion planning and learn to write algorithms to control the sensors and interpret data.
Professor Andre DeHon, Electrical and Systems Engineering
Sensor nodes are often highly energy constrained, particularly when operating on battery power. They can communicate their results off-chip for processing, but that, too, costs energy for data transmission. If we can make the computational energy for key signal processing tasks small enough, we can either avoid off-chip communication or reduce the amount of data that needs to be communicated off-chip sufficiently to achieve net reduction in energy or, effectively, increases in battery life. In this effort, we explore new programmable architectures that minimize energy of computation exploiting a number of techniques including component-specific and lifetime-adaptive mappings, lightweight checking, and spatial processing. 
There are a broad range of opportunities for student engagement, including implementing, optimizing, and benchmarking specific processing tasks, developing algorithms and code to automate design mapping, and developing and optimizing circuits. Student will learn state-of-the-art techniques for energy minimization as well as methodologies for algorithm, architecture, and circuit research.
-  A. DeHon, “Location , Location , Location — The Role of Spatial Locality in Asymptotic Energy Minimization,” 2013.
-  B. Gojman and N. Howarth, “GROK-LAB: Generating Real On-chip Knowledge for Intra-cluster Delays Using Timing Extraction Categories and Subject Descriptors.”
Professor George Pappas, Electrical and Systems Engienering
Redundancy is a well-known method to enhance robustness of systems to failures. For example; in sensor networks, more than one sensor may be colocated to measure a quantity, from which a majority vote mechanism may be used to filter faulty sensors. This conventional notion of (physical) redundancy poses challenges in applications like air vehicles where weight and payload are of interest; and miniature devices where size is a constraint. To address these challenges, we introduce software (or network) redundancy .
Software redundancy exploits the existing network structure and underlying relationship between system components, presenting other ways of estimating, with high confidence, the reading at a failed sensor. An example is an electric circuit where lines between loads have current flows and loads have voltage drops. If an ammeter on a given line fails, for instance, Kirchoff's current law can be used to determine the reading at the failed ammeter. Each sensor will have different ways (libraries), through which it can be estimated. To augment confidence in the desired estimate, we solve an optimization problem that weighs and sparsely combines the most informative of the library elements to minimize the estimation error.
The undergraduate student will build a test bed that implements the concept above, and analyze its results. The student will also study and characterize patterns in the choices of the most informative estimates, with respect to the desired estimation error bound. Familiarity with elementary probability and DC electric circuits will be helpful. Amongst others, the student will learn how errors propagate through functions to affect confidence in an estimate.
-  Q. Maillet, H. Xu, N. Murray, and R. M. Ozay, “Dynamic State Estimation in Distributed Aircraft Electric Control Systems via Adaptive Submodularity,” in Conference on Decision and Control, 2013.
Professor Robert Mauck, Bioengineering
Adult stem cells are a promising cell source for regenerative medicine and tissue engineering applications as they can be induced to differentiate into a number of different cell types (including bone, cartilage, and adipose tissue). To create tissue engineered constructs, these cells are placed in a 3D biomaterial environment and exposed to a variety of soluble signals to induce differentiation. In addition to these soluble cues, mechanical features of the microenvironment influence how cells differentiate, and the time course and strength of this lineage commitment. Our group generates advanced biomaterials for specific application to articular cartilage, knee meniscus, and intervertebral disc tissue engineering. Further, we develop custom mechanical bioreactor systems to stimulate the growth of these engineered constructs in the lab. Ongoing studies are exploring how adult stem cells carry out their role as "sensors" of the local mechanical environment, and seek to identify the molecular, mechanical, and signal transduction pathways that regulate the differentiation process.
Working with senior graduate students and post-doctoral fellows, students will be involved in the design and fabrication of materials for tissue engineering, and the operation of custom bioreactor systems to mechanically perturb tissue engineered constructs and evaluate stem cell response to these perturbations. The students will learn how to carry out basic tissue culture protocols, how to acquire and analyze mechanical test data, how to perform gene expression and histological analysis, and how to interpret their results in the context of cell differentiation pathways.
The goal of the overall research program is to study new approaches to vision sensors . One such project relates to polarization imaging. Polarization is becoming of increased interest in biological imaging and remote sensing. In contrast to intensity and spectral information, polarization provides information about surface orientation and roughness, and is only weakly dependent on the material parameters and overall scattering cross section of the objects in an image . However, measuring the polarization properties of a scene remains challenging due to the lack of on-chip high-quality microgrid polarizers as well as the lack of advanced microgrid based algorithms that can correct for artifacts associated with the specific nature of polarization imaging. Our research aims to develop a microgrid polarimetric imaging system that consists of nano-fabricated wire-grid polarizers integrated on a custom imager . REU students will be involved in optical imager design and testing, optimization of polarizer design and fabrication as well bio-inspired algorithms. The students will learn biological aspects of computational neuroscience, the physics of polarization as well as its engineering applications.