Applications
& Implications

HigiBox is a personal sanitary pad dispenser that combines a motor-driven spiral mechanism, touchless activation, stock monitoring, battery management, and a graphical interface. It stores sanitary pads and automatically dispenses one unit when the user places their hand near the activation sensor.

The system will:

• Detect the user's hand without physical contact
• Rotate a spiral mechanism to dispense one sanitary pad
• Detect whether sanitary pads are available
• Display stock, battery, cycle, and system information
• Monitor voltage, current, and power consumption
• Obtain current date and time through Wi-Fi
• Operate using a rechargeable 12 V battery

The sanitary pads are positioned between the turns of the spiral. When the stepper motor completes the programmed movement, the spiral advances the products and releases the first sanitary pad through the outlet.

Two VL53L0X sensors enable the system to function autonomously:

Commercial sanitary pad vending machines already exist in universities, schools, workplaces, and public restrooms worldwide. These machines use mechanical systems to store and dispense products efficiently at scale. Studying these machines provided critical insights into vertical storage, spiral movement, product outlets, and motor coupling systems.

However, commercial dispensers are typically large metal machines intended for public use. They require coins, buttons, or manual activation and do not provide personalized features.

Most personal-use products found were simple organizers that store sanitary pads vertically or horizontally. These designs require manual removal and refilling, with no integrated sensors, stock monitoring, battery feedback, or digital interface.

HigiBox adapts the operating principle of a commercial vending machine into a smaller device intended for personal use. Its key differentiators are:

The project was developed using information and inspiration from:

• Commercial sanitary pad vending machines and their spiral mechanisms
• Arduino-based vending machine projects
• Existing personal sanitary pad organizers
• Official datasheets for the XIAO ESP32-C3, VL53L0X, INA219, TCA9548A, ILI9341 display, LM2596, ULN2003, and 28BYJ-48 motor
• Arduino and Adafruit library documentation
• Fab Academy weekly assignments and feedback from instructors
• GrabCAD models used as dimensional references
• Physical measurements of sanitary pads and electronic components
• Individual component and breadboard tests
• Mechanical tests using real sanitary pads

These sources enabled me to compare existing solutions, understand required electronics, estimate available internal space, and identify which parts needed custom design specifically for HigiBox.

I will design the main mechanical, electronic, structural, and visual elements of HigiBox:

• Product-storage compartment
• Rotating dispensing spiral
• Motor-to-spiral coupling
• Motor and spiral support
• Product outlet
• Sensor holders and separators

• Acrylic enclosure and internal divisions
• Rounded corner pieces
• Removable panels for access
• Sensor holders and mounting points
• PCB protective case

• Custom PCB with power distribution and signal routing
• XIAO ESP32-C3 microcontroller
• Motor driver circuit
• Sensor interface (VL53L0X × 2, INA219 power monitoring)
• Internal cable layout and routing

• Embedded control program (Arduino/C++)
• Sensor-reading and motor-control functions
• Stock and battery calculation algorithms
• TFT display screen sequence management
• Wi-Fi and NTP time synchronization
• Menstrual-cycle day calculation

• Final system integration and assembly
• Access points for charging and maintenance
• User interface refinement

Autodesk Inventor and Fusion 360 will be used to model the enclosure, internal divisions, spiral, motor coupling, component supports, corners, and complete assembly. Movement and spatial tests will help identify collisions, verify clearances, and evaluate how components fit inside the enclosure.

The 4 mm acrylic panels, internal divisions, covers, display opening, product outlet, and access panels will be manufactured through laser cutting. Laser engraving will add logo and decorative details. Surface contrast techniques (paint filling or backlighting) may improve visibility on white acrylic.

Custom circuit boards will be manufactured using a PCB router. The traces, pads, holes, and external board outline will be milled from single-sided copper-clad board. Multiple iterations may be needed to optimize trace routing, pin assignments, and power distribution.

FDM 3D printing will manufacture the dispensing spiral, motor coupling, sensor holders, curved corners, PCB case, and internal supports. The spiral will require careful support structure planning due to its helical geometry.

Acrylic and printed parts will be assembled using screws, threaded inserts, adhesives, and custom supports. Physical fitting tests will verify dimensional tolerances, panel alignment, corner compatibility, spiral movement, motor positioning, product clearance, and maintenance access.

This Bill of Materials includes electronic components, fabrication materials, power system, mechanical materials, and custom PCB resources required to build HigiBox. Materials supplied by Fab Lab ULima are included using estimated replacement costs.

Item	Description	Source	Cost (USD)
2.8" TFT LCD Touchscreen	Displays cycle, battery, stock, and system info	Zacatrex Electrónica	$28.57
TCA9548A I2C Multiplexer	Connects two I2C sensors with same address	Zacatrex Electrónica	$2.29
ULN2003 Motor Driver	Controls stepper motor coils	Zacatrex Electrónica	$1.43
28BYJ-48 Stepper Motor	Rotates dispensing mechanism	Fab Lab ULima	$2.86
LM2596 Step-Down Converter	Reduces 12V battery to 5V	Zacatrex Electrónica	$2.00
INA219 Power Sensor	Measures voltage, current, and power consumption	Zacatrex Electrónica	$5.71
Custom 12V Battery	Powers system, includes USB Type-C charging	Zacatrex Electrónica	$20.00
VL53L0X Sensors (× 2)	Monitor stock and detect user's hand	Zacatrex Electrónica	$6.86
Jumper Cables	Prototyping and integration tests	Fab Lab ULima	$1.43
White Acrylic Sheet, 4mm	Enclosure and internal divisions	Fab Lab ULima	$30.00
PolyLite White PLA	Supports and mechanical parts	Fab Lab ULima	$20.00
PolyLite Black ABS	Stronger printed components	Fab Lab ULima	$18.57
XIAO ESP32-C3	Controls sensors, display, motor, Wi-Fi, logic	MTLab UNI	$14.29
Copper-Clad PCB	Custom circuit board manufacturing	Fab Lab ULima	$1.14
SMD Pins & PCB Connectors	Connect external modules to custom PCB	Fab Lab ULima	$1.14
Power Switch	Turns complete electronic system on/off	Fab Lab ULima	$0.57

Having all the components available does not mean the project is complete. Their final positions, supports, connections, and interaction still need to be validated through testing.

At this stage, the general concept and system architecture are defined, but several integration decisions still need validation before finalizing the prototype.

The cables must travel between the PCB, display, sensors, motor driver, battery, and power modules without interfering with the spiral or product outlet. Key decisions:

• How should cables be routed inside the enclosure?
• Where are the optimal fixing points or guides?
• Do actual cable widths fit within planned internal spaces?

Final positions of the PCB, battery, LM2596, INA219, multiplexer, and motor driver must be confirmed. The electrical sketch helps understand connections, but physical placement inside the actual structure requires testing.

Can the two VL53L0X sensors, INA219, and TCA9548A communicate reliably in the same circuit? Testing will confirm the I2C multiplexer strategy and data integrity across multiple sensors.

The stock sensor must point through the central area of the spiral. Key questions:

• Should it be positioned beside the motor, opposite the motor, or closer to the storage compartment center?
• How does laser alignment, available space, and motor interference affect placement?
• What are accurate distance readings with and without sanitary pads?

The hand-detection sensor must be accessible from the exterior without accidental activation by nearby objects. Testing will determine:

• Optimal angle and position near the product outlet
• Appropriate detection threshold
• Distance range for reliable activation

The motor shaft, coupling, and spiral must remain aligned during rotation. Testing will validate whether the printed coupling maintains spiral position without excessive movement, bending, or vibration.

Electronic modules must be protected but accessible for charging, repairs, wiring adjustments, and component replacement. This requires removable panels and adequate space around the battery, PCB, connectors, and power switch.

When the hand-detection sensor is activated, the motor must rotate the dispensing mechanism and release one sanitary pad. The TFT display must show the current status of the dispenser.

The prototype will be considered functional if it can:

• Detect the user's hand
• Activate the motor only once per detection
• Detect whether sanitary pads are available
• Release one product through the spiral mechanism
• Display stock and system information
• Operate using the rechargeable battery
• Maintain stable communication between modules
• Protect the electronics inside the enclosure
• Allow access for charging and maintenance

The following functions will be considered additional improvements rather than minimum requirements:

• Menstrual-cycle calendar
• Current cycle-day calculation
• Battery percentage display
• Wi-Fi and NTP time synchronization
• Motivational reminder screens
• Future mobile application connectivity
• Low-stock notifications
• Improved acrylic lighting and visual feedback