Engineering and Research Portfolio

Sid Annapragada
B.S. Electrical Engineering and Behavioral Neuroscience, Northeastern University
Interested in merging neuroscience, medicine, and engineering to help people struggling with mental and neurological illnesses
Projects
Research

Datta Lab @ Harvard Medical School
I worked at the Datta Lab for a total of 2 years under Dr. Sandeep Robert Datta.
Engineering:
Developed instrumentation for recording data from freely moving mice
An Active Commutator device I designed to track mouse head angle and actively rotate a tether connected to head sensors to alleviate cable tension on the body of a freely moving mouse.














Watch how the rotor follows the IMU. Note the control loop is pretty smooth, and the signal passes through a pretty fast moving system. But this pancake design wasn’t reliable enough, hence the switch to the cylinder design.
The mouse has an IMU and breathing sensor attached to the head, and the tether is being rotated based on the IMU angle to compensate for cable tension. Slip ring inside allows for commutation.
Just the top part of it, don’t have a good photo of the whole thing.
From left to right: rotor board, motor, slip ring, stator board.
Used a pancake design with rolling pin connections to transmit signals. Didn’t work super great, but it did work!
Small amplifier circuit with DAC for offset adjustments for a thermistor sensor implanted in the nose of freely moving mice to sense breathing.
Plugged into another breadboard connected to an arduino. Mouse is tethered to this amplifier.
Test first!
I can solder! The green wire is very nice 30AWG wire wrapping wire, good for rework
Small, implantable LED array for simple patterned optogenetic stimulation in freely-moving mice.
Actually building the flex LED array was really hard. Here it is under the scope.
Only put four LEDs on this one. Ultimately, manufacturing was too difficult and the lighting too diffuse, so we didn’t end up using this device. But it was a fun build.
Ultra-lightweight IMU headstage for monitoring head movements in freely moving mice. The lab ended up using this device along with the commutator to collect a bunch of mouse behavioral data for Caleb Weinreb’s Keypoint Moseq paper (citation below). My engineering and data collection contributions earned me a co-authorship.
Publication:
Weinreb, C., Pearl, J.E., Lin, S. et al. Keypoint-MoSeq: parsing behavior by linking point tracking to pose dynamics. Nat Methods 21, 1329โ1339 (2024). https://doi.org/10.1038/s41592-024-02318-2
Did a lot of debugging and testing work to get this odor delivery system working well.
My primary project at the Datta lab involved studying a mouse social olfactory behavior called the social transmission of food preference. In this paradigm, a simple odor input from the breath or excrement of another mouse induces a change the exposed mouse’s food preference: an interesting type of learning. We used various techniques to study this including many behavioral recordings with fiber photometry, optogenetics, and behavioral videos as odors and stimuli were being presented. I was responsible for helping build the experimental rigs, running experiments, and writing python code to scale up our analysis pipelines from handling single sessions, to TBs of data.
Shown are photos of some of the computer vision algorithms I implemented and some example data visualizations.



Live fiber photometry data from a headfixed mouse on a wheel during odor presentations. Breathing, running, and a video of the face are being collected as well. I was responsible for helping build the experimental rig, collecting data, and writing analysis and visualization pipelines.
Example computer vision task I needed to complete for our video analyses
Example of an analysis I did to quantify whisker motion
Example visualization of keypoint tracking data of a mouse and dish of food in an arena, recorded from above.
Example model I trained to detect mice, using Detectron2.

Action Lab @ Northeastern University
I worked at the Action lab for 4 years during school, including a 6 month co-op under Dr. Dagmar Sternad.
Engineering:
Developed a device to record human movements while interacting with a movement game.
Custom designed device to measure arm angle during an interactive game-like experiment. Involved mechanical, electrical, firmware, software development.
Full device CAD assembly



PCB with MCU and USB connection for interfacing with encoder, user interaction button, and the MATLAB app on the host computer. Assembled by hand with a stencil.
Set up the device in our collaborators lab at Brown, and we took this photo to commemorate.
Conducted experiments studying human movement and complex object manipulation in healthy and stroke populations.
My primary personal project at the Action Lab was called the Bell Task, an experiment where we investigated how humans control a bell, which is a complex object requiring precise force control.
I also helped collect data for and rewrite a python-based computer vision system for an experiment called Magic Table. In this experiment, we record stroke and healthy patients manipulating a 3D printed cup with a ball inside (a complex object again) and analyze their movments. I upgraded the code to be compatible with a 3D depth camera instead of a 2D webcam, for future 3D experiments, and made it easier for the user to use.



Shown is the camera color and depth views, with the orange cup and green ball being tracked as I move the cup around.
Handwritten in Python without AI. I walk through the whole flow of the app from experiment setup to recording and saving. My contribution of this app and data collection assistance earned me co-authorship on two conference poster presentations and a co-authorship on a manuscript in-prep
Poster describing the bell task, my primary science project in the Action Lab. Presented as first author at the Society For Neuroscience Conference 2024, Chicacgo, USA. I also presented earlier work on the same project at the Society for the Neural Control of Movement, 2023, Victoria, Canada.
Just an example visualization of some of our bell data. Notice some of the analyses we did such as Mutual Information calculations.
Audio transcription app. Written in Python, with some AI. Uses WhisperX speech to text model.

Engineering Capstone: Rhythm Rehab Revolution
Engineering Capstone Project: Rhythm Rehab Revolution, a custom controller and game for finger and hand rehabilitation. Controller incorporates haptics, and force-sensing buttons for complex rehabilitation paradigms. I did the hardware design (EE, ME). Firmware and Software were done by teammates (Dominik Zajac, David Fatheree, Iris Wang, Andrew Briasco-Stewart)
Fully assembled custom force-measuring handheld controller for a handmade rehabilitation-focused rhythm game.
Custom designed handheld controller for a rhythm based rehabilitation game.











Watch how I play the rhythm game, making discrete movements with right and left swipes, and rhythmic finger movements. This combination of rhythmic and discrete movement combined with force sensitivity makes this game and controller unique in the rehabilitation space. Gesture detection needed some refinement ๐
Watch the buttons light up and try to listen as the controller vibrates with each button push. The visual and haptic stimulus enhances the sensory engagement for the user and is believed to improve rehab results.
Everything is wired up, including the battery and force sensors!
Assembled by hand with a stencil. Contains battery management, BLE MCU, IMU, LED driver, analog front end for FSR sensors, haptic motor. Note the touch of debugging/rework needed. I swapped SCL and SDA, rookie mistake.
Breadboard setup to test some of the ICs we used on the final board and spin up firmware.
Render of SLA printed top shell, holding four force-sensitive, spring loaded button modules.
Render of SLA printed bottom shell, holding a haptic motor and various mounting points.
Getting good ergonomics was a big design challenge for me
Took some refinement to get our 3D prints to feel good in the hand
Just four small FSRs for sensing finger forces.
Stroke often results in dexterity loss, so having a way to progressively and personally train this is useful for rehabilitation. Incorporating gross arm movements helps improve whole body coordination training, and varying between rhythmic and discrete movements engages more of the motor system.


We developed an algorithm that used the on-board IMU to detect right and left swipe gestures as part of the training program.

Dynamica
Independently started research project involving developing devices and software to assess finger dexterity in stroke and aging populations. I am responsible for the scientific idea, leadership, mechanical design, and software development. Team of 3 other engineers involved. Working with Dr. David Lin at Mass General Hospital and Dr. Dagmar Sternad at Northeastern University. Other engineers involved: Walter Stadolnik (EE), Dominik Zajac (firmware), and Demitri Kokoros (mechanical design support).
A device for precisely measuring finger forces during custom Python-based experimental tasks with stroke patients, to assess dexterity changes. I did the mechanical design and software. Collaborators did the PCB and firmware.
Tabletop mounted, fully adjustable finger force measurement device for stroke rehabilitation research.






Simple GUI running to read out the force sensors, while I test it out.
Designed by Walter Stadolnik. This board contains an MCU, an analog front end for the sensors, an IMU, haptic motor, and power management.
SLA printed force-sensitive button design, with snap-hooks and spring-loaded force applicator.
A 3D mockup of a handheld version of the finger force measurement system, with adjustable sensor positions.
~70 million Americans are over 65 โ and most will lose hand dexterity as they age. This loss signals cognitive decline and reduced independence. Yet clinicians have no way to accurately quantify dexterity under real-world conditions.
We are developing a series of devices to solve this problem by bringing low-cost, highly accurate force sensors to an accessible form factor for impaired populations with a neurology and rehabilitation informed software analysis and game suite.




Clinicians tend to use tools that are very qualitative, giving only time to completion or other single number metrics or very expensive, with advanced robotic technologies. We are seeking a middle ground.
We validated the market gap with a handful of researchers in the field.
Based on the gap we found, we identified two priorities: making our device accessible and reasonably-priced, and making it quantitative with enough sensing and actuation capabilities to realistically perform rehabilitation and monitoring functions.
Using the design priorities we found, we can visually demonstrate the market gap.

Sonar Transceiver
Developing a long-range sonar transceiver for underwater biomimetic robots. PI: Joseph Ayers
Render of final circuit board design. Contains a receiver module (log amp front end) with tone-decoding, a transmitter module (Class AB, 2W), PIC MCU + custom C firmware, power management, and a USB interface.





Assembled by hand with a stencil. Battery management section not populated. Hand-assembled board used for testing.
We placed the two ceramic transducers into a bucket to test simple transmission and reception. Scope picture is next in the gallery.
Red is the input into the transmitter and yellow is the received signal.
Pardon the crappy soldering, I didn’t have a microscope at the time. Log amplifier for the receiver front end.
I smudged the paste on this IC by accident :(, took a bit to clean, but it reflowed and worked fine!
Personal and Consulting

Daneel MK 1 Robot
Autonomous robot designed for the Trinity Firefighting Robotics Competition.
I did mechanical, electrical, firmware, and software. IR, ultrasonic, encoders, IMU sensors included.



PCB containing MCU, battery management, various sensor interfaces, and motor control interfaces.
Pardon the wiring, I was making it look messy on purpose for a before/after shot. But I lost the after shot.

Miscellaneous Board Designs
Various board designs done for clients and myself
Contains low-noise DC power supply design with analog front end and ADC.








Just demonstrating a simple soldering job. This is a BLE enabled development board that I designed.
Low-power, low-cost design for a cellular-based water leak detector. Contains battery management, analog sensor interface, and cellular module.
Discovered a bug where the cell modem would draw a large power transient on transmission. Had to swap the LDO to be able to handle more current and surges. Fun debug and fix!
Solid State relay board for switching ~20A loads.
Assembled unit in waterproof enclosure
An analog op-amp circuit which simulates the hindmarsh-rose neuron equations to generate spiking electrical activity. Lost the photo of the real board ๐

Wifi Enabled Kitchen Automation
A series of wifi-enabled IOT devices for a client for kitchen automation. Includes an automatic powder dispenser, load cell sensor, and AC relay controller. Worked on with Dominik Zajac.
Wifi enabled automated powder dispenser. Contains a load cell and stepper driver with custom C firmware to automatically dispense a user-specified weight of loaded powder.










Lots of issues that we had to fix, like vibrations, and backflow!
Custom PCB with Wifi module, load cell amplifier, and stepper motor driver.
A little rework needed on the stepper driver for the dispenser board
Prototype load cell amplifier PCB with wifi module
Prototype Wifi enabled relay control board

Small Projects
Various miscellaneous electromechanical builds
Hardware for lab kit for freshmen engineers to program their own strain testing device. Contains a current sensor and motor driver, and interacts with student MATLAB programs via arduino.






I run the strain tester with matlab as a little example. The collected data is not shown, but the device records the current flowing through the motor and uses physics to back calculate the amount of force being applied to the specimen.
Note the arduino, current sensor board, and off-the-shelf motor controller.
Freshmen engineering project. Science exhibit demonstrating electromagnetism with two electromagnetic race cars. Includes custom software and a PCB for driving the magnets. I was responsible for mechanical and electrical design.
This was an early test. The cars are clearly not synchronized, and a bit jumpy. But still cool ๐
board for pulsing two electromagnets
I programmed a Microchip DSP in C to simulate the firing of a neuron and be adjustable via a potentiometer. Notice how the firing goes from burst to a normal train.

Agriculture Technology
Various devices made as a consultant to an agriculture technology startup
Contains water speed, pressure, and turbidity sensor, with interface board to monitor soil runoff from fields.









Note the O-ring and acetone-smoothed PLA 3D print.
10+ units deployed in the field. An interface board to connect environmental various sensors to an off-the-shelf datalogger.
These got deployed in the field!
Soil Moisture monitor build, with power timer, sensor interface, battery, and cell mesh network module
Moisture Monitor PCB
These got deployed in the field!
Sheet metal design for a flume for runoff