Project Overview
The Thermistor Cleaner is a user-friendly device that automates the cleaning of food thermometer probes in dining halls, reducing cross-contamination risk and ensuring food safety compliance with the simple push of a button.
Problem Statement
In campus dining halls, the same thermometer probe is frequently used to check the temperature of multiple food trays. Without proper cleaning between measurements, this creates a significant cross-contamination risk. Staff often neglect thorough cleaning due to time constraints or inattention, compromising food safety standards.
Our challenge was to design an automated solution that would ensure consistent, thorough cleaning of the thermistor probe between each use, regardless of staff attentiveness or time pressure.
After conducting interviews with dining hall staff to understand their workflow and pain points, we developed a device that attaches directly to standard food thermometers. Our solution features a mechanical scraping mechanism combined with an internal brush system that activates with a single button press, effectively removing all food residue from the probe in seconds.
Design Process
Research & Discovery
We began with user research, interviewing dining hall workers to identify key pain points in their food temperature measurement workflow. This revealed the critical issue of thermometer probe cross-contamination caused by inconsistent cleaning practices between readings.
Our primary insights:
- Staff needed to regularly measure multiple food trays in succession
- The same thermometer probe was used across different food items
- Thorough cleaning between measurements was often overlooked or rushed
- Any solution needed to be quick, simple, and require minimal effort
Conceptual Development
After evaluating several potential approaches, we determined that a mechanical scraping mechanism combined with a brushing system would provide the most thorough cleaning. This dual-action approach would remove both surface residue and more stubborn food particles.
Initial design considerations included:
- How to create linear motion to travel along the probe length
- Ensuring the cleaning mechanism completely surrounds the probe
- Power requirements and activation method
- Attachment mechanism to standard thermometers
Engineering Solutions
Our initial investigation into linear actuators revealed they were beyond our project budget. We pivoted to using solenoids, which offered a more cost-effective solution but presented a significant challenge: their limited range of motion (approximately 2mm).
To overcome this limitation, we designed an innovative lever system that amplified the solenoid's movement, extending the effective range from 2mm to approximately 2 inches—sufficient to clean the entire probe length.
Key components of our final design:
- Laser-cut acrylic housing for durability and aesthetic appeal
- 3D-printed lightweight lever arms to minimize inertia
- Solenoid-activated mechanical system
- Integrated brush and scraper for thorough cleaning
- Single-button activation for ease of use
Product Gallery
Component Assembly
Exploded view showing the key mechanical components including the solenoid, lever system, and cleaning mechanism.
Internal Mechanism
Overhead view of the internal lever system that amplifies the solenoid's motion for full-length probe cleaning.
Side Profile
Side view showing the streamlined design and the relationship between the cleaning mechanism and thermometer probe.
The compact design attaches directly to standard food thermometers without impeding normal operation.
Technical Specifications & Features
Mechanical Specifications
- Dimensions: 4" × 2.5" × 1.5" (approx.)
- Materials: Laser-cut acrylic housing, 3D printed PLA lever arms
- Actuation: 5V solenoid with lever amplification system
- Cleaning Range: 2" vertical travel
- Weight: Approximately 150g
User Features
- One-Touch Operation: Single button activation for complete cleaning cycle
- Universal Attachment: Compatible with standard food thermometers
- Quick Cleaning: Complete probe cleaning in under 3 seconds
- Dual-Action: Combined scraping and brushing for thorough cleaning
- Replaceable Parts: Easily serviced cleaning components
Design Considerations
The final design reflects careful attention to both practical functionality and user experience:
- The transparent housing allows for visual confirmation of the cleaning process
- The lever system was carefully balanced to maximize range while maintaining cleaning pressure
- Button placement was optimized for thumb operation while holding the thermometer
- Mechanical components were designed for durability in a food service environment
Impact & Learning Outcomes
Project Impact
The Thermistor Cleaner demonstrates how thoughtful engineering design can address everyday workplace challenges:
- Improves food safety by ensuring consistent probe cleaning between measurements
- Reduces the risk of cross-contamination in institutional food service settings
- Simplifies compliance with food safety protocols for staff members
- Shows how mechanical amplification can overcome actuator limitations in compact devices
Key Learnings
Technical Skills
- Solenoid actuation and power requirements
- Mechanical advantage systems design
- CAD modeling for laser cutting and 3D printing
- Rapid prototyping and iterative design
Design Process
- User-centered design research methods
- Budget-constrained engineering solutions
- Effective stakeholder interviewing
- Constraint-driven innovation