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Writer's pictureY. Osroosh, PhD

DIY Fruit Wetness & Temperature Sensor: Mimicking Nature for Better Crops

Remember how a few years back we discussed a leaf wetness sensor (like the INSHU LWS) and the potential for a similar sensor for fruits? Well, today I'm excited to share a design concept I've been working on – a DIY fruit wetness and temperature sensor specifically for small fruits like blueberries! 


Why a Fruit Wetness Sensor?

Fruit surface wetness plays a crucial role in various aspects of fruit health. Excessive wetness can lead to cracking, disease development, and ultimately, reduced yield and quality. Imagine having a sensor that mimics a small fruit, allowing you to precisely measure wetness levels and prevent these issues.


The Design Concept

 This sensor design utilizes a two-pronged approach (Fig. 1): 


  • Mimicking a Fruit: The core is a 3D-printed "filler" shaped like the top and bottom halves of a fruit.

  • PCB Electrodes: A two-layer printed circuit board (PCB) with strategically placed electrodes (think fruit slices) is embedded within the filler.



Fruit surface wetness sensor
Figure 1. Fruit surface wetness sensor design

The magic happens with frequency domain reflectometry. An oscillator sends an electromagnetic wave through the electrodes (Fig. 2). If water is present, it changes the wave's behavior. This change is detected by a circuit, providing a measurement of the fruit's surface wetness.

 

Fruit surface wetness sensor
Figure 2. Fruit surface wetness sensor working principal

A temperature sensor, like a thermocouple or a digital one, can be integrated to monitor both wetness and temperature simultaneously. Temperature measurements can be used to correct the readings for temperature dependency. 


Benefits

This DIY sensor offers several potential benefits: 


  • More Accurate than Leaf Wetness Sensors: By mimicking a fruit, it provides a more precise indication of wetness levels and duration.

  • Reduced Fruit Cracking: By monitoring wetness levels, you can identify and address situations that might lead to cracking, especially in sensitive varieties.

  • Improved Disease Prevention: Certain fruit diseases thrive in specific wetness and temperature conditions. This sensor can provide valuable data for disease prediction and prevention strategies.

  • Optimized Fruit Quality: Precise wetness and temperature data can help you implement better management practices to ensure optimal fruit quality and shelf life.


Building Your Own Sensor

Important Note: While I'm sharing the design concept, this is not a complete DIY guide with step-by-step instructions. Building this sensor requires some technical expertise in electronics and circuit design. However, if you're comfortable with electronics and have access to tools like a 3D printer and PCB fabrication, this design concept can be a great starting point.


I hope this design concept ignites some creative ideas for your next DIY project and empowers you to take better care of your fruits!


Additional Note: This design concept, which has been dormant for several years, might not have immediate commercial value. However, I believe it holds significant potential for research and could contribute to advancements in fruit cultivation and preservation.

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