Author: ginaseo

This week, I completed the final LED response validation and finalized the wiring organization for our project. All hardware components were tested together in a full system run to ensure stable operation and reliable communication between pressure sensors, NFC scanners, LED indicators, and the central microcontroller. I’m in the process of integrating the temperature and humidity sensors as well as the final LDR into the system and validated their readings through preliminary tests.

A major focus this week was preparing the hardware for demo by physically reinforcing all sensor placements, optimizing cable routing to minimize visual clutter and signal interference, and finalizing the concrete plan to securely wrapping the system in a silicon mat to complete the device’s final assembly.

One of the main challenges this week was time management—balancing system testing, hardware reinforcement, sensor integration, and predictive logic development within a very compressed timeline. Minor troubleshooting was also needed to stabilize the temperature sensor readings, which initially showed fluctuations due to wiring noise.

Looking ahead, my final steps before the demo include running complete, end-to-end system tests under different simulated user scenarios to ensure reliability during the live demo. I will also polish the LDR wake system and humidity sensor integration.

Throughout this final phase, I relied heavily on rapid iteration and hands-on debugging, drawing from earlier informal learning and adapting techniques on the fly. Reflecting on this capstone, I feel that this project significantly strengthened my ability to manage full hardware-software integration, troubleshoot real-time sensor systems, and deliver a functional prototype under tight deadlines.

This week, I completed the initial circuit verification and LED implementation for our project. I conducted validation tests for pressure detection, manual inventory adding, and NFC sticker scanning, ensuring that the hardware components performed as intended. I also began LED response testing, which is ongoing and scheduled to be completed tomorrow. A major focus throughout the week was ensuring stable power delivery across all hardware components, which required careful checking of each connection and verifying overall system performance.

One of the main challenges I encountered was managing the organization of wiring while maintaining stable and reliable power flow. Additionally, I had to make minor adjustments to sensor positioning to optimize detection consistency, especially during the pressure detection tests.

Looking ahead, my next steps are to complete the LED response validation, finalize the wiring organization to prepare the hardware for presentation, and integrate temperature and humidity sensors into the system before the upcoming demo. I also plan to implement predictive logic that will help recommend against unnecessary grocery purchases based on user inventory. Finally, I aim to fully wrap the device with a silicon mat to finalize the hardware assembly.

Throughout the process of designing, implementing, and debugging the project, I found it necessary to strengthen my knowledge of stable power distribution techniques and real-time sensor validation strategies. I also had to learn practical wiring organization methods to minimize signal noise and maintain consistent performance under different operating conditions. To acquire this new knowledge, I relied heavily on informal learning strategies, including watching targeted YouTube tutorials, reading discussions and troubleshooting posts on Stack Overflow and Arduino forums, and studying relevant sensor datasheets. Accessing real-world examples and project references online helped me quickly adapt and apply new techniques without the need for formal coursework, allowing me to troubleshoot and optimize our hardware setup more effectively.

I successfully completed the wiring and soldering of the LED subsystem. Initially, we attempted to solder four separate 4-LED strips (16 total) into a square formation to fit the base of our design. However, we encountered a major roadblock: current flow inconsistencies due to segmenting the strips. To resolve this, we opted not to cut the LED strips. Instead, we used a continuous 16-LED strip and geometrically folded it into a square pattern to maintain uniform current flow and simplify the wiring layout. This new configuration has been tested using our power booster and logic level shifter, which step the Arduino’s 3.3V output up to 5V for the LED signal and power. All 16 LEDs now light up consistently with no drop in brightness, verifying the effectiveness of our revised wiring approach. The 4 squares of LEDs will now take up 4 pins in total on our main ESP32 board.

I’ve completed testing the power circuit stability. Using a multimeter, I confirmed that the voltage booster consistently outputs ~5V under full LED load, and the logic level shifter correctly translates the Arduino’s 3.3V signal to 5V for LED data input. The system maintained stable performance with no flickering or voltage drops.

I still need to complete testing for the light sensor, which is scheduled for next week. This will involve simulating fridge door open and close states using a flashlight to verify that the sensor correctly detects changes in ambient light and triggers power-off behavior when lux levels drop below the threshold.

To verify pressure sensor accuracy, we will place 10 items of varying weights (≥50g) on the GlowFresh pad, testing sensor response with and without the silicone mat interface. I’ll confirm that placement and removal are consistently detected, aiming for a 98% success rate with minimal false positives. We’ll also evaluate sensor sensitivity and response when two items are stacked, ensuring that changes in total force are correctly registered.

This week, I soldered the LEDs into square shapes, with one pad containing 16 LEDs and completed the LED code on a separate ESP32, ensuring it produces the desired color outputs reliably and gradients effects. This weekend, I began integrating the ESP32 with the rest of the circuit; early tests indicate that the system is communicating properly and that the LEDs are responding as expected.

On Sunday, we plan to meet to finalize our testing before our demos on Monday and Wednesday, and we will also be discussing the Apple Developer license for our app and seeing how this may change our timeline. Furthermore, I plan on laser-cutting squares of thin acrylic and order test silicon sheets to wrap our project around our electronics before molding step.

Overall, this progress marks a key step toward a fully integrated system as we move closer to our critical demo deadlines.

This week, I focused on sourcing and researching components needed for the LED strip circuitry. Specifically, we required a signal and power booster to meet the 5V requirement of the LED strips while operating on a 3.3V system. Although I had planned to begin LED integration, our ESP32 was confiscated by TSA at an airport, preventing direct testing. In the meantime, I wrote and prepared code in the Arduino IDE to facilitate testing once we receive a replacement next week.

The project remains on schedule. For the upcoming demo, we plan to integrate the LED system with NFC scanners and tags. This will allow the system to correctly recognize stickers on objects placed in different zones of the pad and send real-time notifications to the frontend.

Next week, I aim to finalize the LED setup by cutting the strips into four sections, each corresponding to a specific zone of the pad. The goal is to enable the LEDs to change colors—green, yellow, or red—based on backend notifications.

This week, I completed the rapid prototyping of 4 pressure sensors and an LDR in Arduino IDE, with strong initial thresholds set for sensitivity. The pressure sensors are connected to GPIO pins (32, 33, 34, 35), and I’ve assigned names to each sensor for easy identification in the serial monitor. The system checks for pressure detection, and prints the sensor name and value when pressure is applied. For the light sensor, I used a TEMT6000 on GPIO 26, and set a threshold to detect changes in the light status. The sensor was sensitive enough to detect when my hand came closer to cover the circuit, simulating the fridge door closing, but it was not affected by the LED light. I’ve also connected an LED to GPIO 25 to indicate the light status — if the light is on, the LED lights up, and if the light is off, the LED is turned off. A demo video is shown here.

Additionally, Jess, Sarah and I completed the design report by Friday. I mainly focused on research and writing on hardware components, justifications, battery life, problem statement and solution overview, and system diagrams.

Overall, my team and I are making steady progress and are on schedule.

Some roadblocks included the late delivery of the LED, NFC tag, and NFC scanner, so we weren’t able to integrate everything over Spring break. However, I plan to integrate the LED system with Jess next week. Even further, with Jess’s progress on the Bluetooth (BLE) functionality and WiFi setup for the ESP32, I will be able to help put together our initial prototype + real LED strips with Wifi data transfer mechanism, which will be key for moving forward with the integration.

This week, I focused on finalizing our design slides and collaborated with Jess and Sarah to thoroughly review our hardware components for the presentation. We ensured that all elements were clearly documented and that our explanations were concise and well-supported. Additionally, after internal discussions and consulting with a Master’s-level Mechanical Engineer experienced in working with pressure and weight sensors in various projects, we decided to transition from force-sensitive resistors (FSRs) to weight sensors for greater accuracy and reliability. To support this shift, I began exploring different weight sensor options that align with our design needs. However, we are concurrently testing pressure sensors to validate our decision, as we have acquired square and small circle pressure sensors from the Ideate lab for evaluation.

Our decision to move away from pressure sensors stems from their inherent limitations in detecting stacked items. Pressure sensors measure force per unit area, meaning that if the added item distributes its weight over a large surface, the overall pressure change might be too minimal to register accurately. This could lead to unreliable or inconsistent readings. In contrast, a load cell strain gauge directly measures total force applied, making it far more effective at detecting subtle weight changes due to stacking. By using a load cell, we can ensure a much more precise and responsive detection system, which is crucial for our application.

In addition to refining our sensor choices, I addressed concerns regarding the fabrication of our electronics with FDA-safe silicone. On Thursday, I met with Cody from Ideate to discuss the scope of our project, our progress so far, and the feasibility of using food-safe silicone for the final product. We received great news—facilities are available to help us create silicone molds using FDA-compliant materials, as the Creative Soft Robotics class is currently working on similar projects involving silicone mold printing. Cody demonstrated how straightforward the process would be, as long as we finalize the sensor layout.

The decision to use a weight sensor aligns well with this fabrication plan, as we can calibrate it precisely to account for any pressure applied by the silicone casing. Additionally, Cody helped us select free acrylic sheets that I can laser cut (since I already have clearance for laser cutting) to create plates for sandwiching the strain gauge weight sensor. This setup will provide a stable and effective means of integrating the sensor into our final design.

Looking ahead, I plan to begin drafting the design report since the deadline is quickly approaching. Simultaneously, I will start assembling the prototype with the team to ensure we have a functional version before spring break. Having a physical build will give us a much clearer understanding of any potential integration challenges, allowing us to refine our design early in the process. We’re making steady progress, but accelerating our pace now will help us stay ahead of upcoming deadlines.