OpenDendrometer Can Measure How Your Tree Feels

There are various ways to measure plant health, and we’ve seen many projects creating open-source solutions. One we haven’t seen is a dendrometer, which involves measuring various physical dimensions of trees to track their health and growth. [John Opsahl] is changing this with the OpenDendrometer, a tool for tracking the diameter of tree limbs and fruit.

Tiny changes in diameter take place throughout the day, and tracking these changes allows deviations to be detected, which can be a sign of water stress. Over weeks and months, these measurements can be used to measure growth and fruits’ progress to harvest. [John] found that a digital tire tread depth gauge can work well for this application. Many of these gauges use the same electronics as the cheap digital calipers, for which the serial protocol was reverse engineered more than a decade ago. The OpenDendrometer connects the tire depth gauge to a microcontroller via a 1.5V level shifter, which logs measurements to an SD card while using a DS3231 RTC for accurate timestamps. The RTC can also be used to wake up the circuit at the required intervals to save battery power. For the initial proof of concept [John] is using an Arduino Pro Mini, but plans to move to an ESP32 at a later stage to allow wireless data transmission.

Everything will be housed in a 3D printed enclosure with a foam cord gasket to make the device weather resistant. A mounting rod on the outside of the enclosure with adjustable thumbscrews allows the OpenDendrometer to be attached to any part of the tree. We plan to keep an eye on this project and look forward to seeing the data it produces.

For the other ways of measuring plant health, we’ve covered everything from soil moisture to Normalized Difference Vegetation Index and even plant weight and even pot plant weight.

How To Grow (Almost) Anything

An off-shoot of the infamous “How to Make (Almost) Anything” course at the Massachusetts Institute of Technology, “How to Grow (Almost) Anything” tackles the core concepts behind designing with biology – prototyping biomolecules, engineering biological computers, and 3D printing biomaterials. The material touches elements of synthetic biology, ethics of biotechnology, protein design, microfluidic fabrication, microbiome sequencing, CRISPR, and gene cloning.

In a similar fashion to the original HTMAA course, HTGAA works by introducing a new concept each week that builds up to a final project. Students learn about designing DNA experiments, using synthesized oligonucleotide primers to amplify a PCR product, testing the impact of genes on the production of lycopene in E coli., protein analysis and folding, isolating a microbiome colony from human skin and confining bacteria to image, printing 3D structures that contain living engineered bacteria, and using expansion microscopy (ExM) to visualize a mouse brain slice. The final projects run the gamut from creating a biocomputer in a cream to isolating yeast from bees.

Growing out from an initiative to create large communities around biotechnology research, the course requires minimal prior exposure to biology. By working directly with hands-on applications to biodesign concepts, students are able to direct apply their knowledge of theoretical biology concepts to real-world applications, making it an ideal springboard for bio-inspired DIY projects. Even though the syllabus isn’t fully available online, there’s a treasure trove of past projects to browse through for your next big inspiration.

Long-Range RFID Leaflets

Pick a card, any card. [Andrew Quitmeyer] and [Madeline Schwartzman] make sure that any card you pick will match their NYC art installation. “Replantment” is an interactive art installation which invites guests to view full-size leaf molds casts from around the world.

A receipt file with leaf images is kept out of range in this art installation. When a viewer selects one, and carries it to the viewing area, an RFID reader tells an Arduino which tag has been detected. Solid-state relays control two recycled clothing conveyors draped with clear curtains. The simple units used to be back-and-forth control but through dead-reckoning, they can present any leaf mold cast front-and-center.

Clothing conveyors from the last century weren’t this smart before, and it begs the question about inventory automation in small businesses or businesses with limited space.

We haven’t seen much long-range RFID, probably because of cost. Ordinary tags have been read at a distance with this portable reader though, and NFC has been transmitted across a room, sort of.

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