Purdue University Develops 3D-Printed Groundwater Sensor: Providing Low-Cost Scientific Instruments for USGS

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Researchers at Purdue University have developed a 3D-printed, open-source groundwater flow sensor, designed to serve as an alternative to the U.S. Geological Survey’s (USGS) existing expensive, proprietary sensors. This patent-pending device costs only a few hundred dollars to assemble, a fraction of the cost of commercially available hardware.

The project is led by Jacob Hosen, Assistant Professor of Internet of Things and Ecological Analytics in Purdue University’s Department of Forestry and Natural Resources, in collaboration with the open-source hardware non-profit organization River Restoration Intelligence and Verification (RRIV). Funding comes from the USGS’s Next Generation Water Observation System (NGWOS), a division dedicated to developing cheaper and faster technologies for water resource data collection.

A Sensor that Can Be 3D Printed and “Baked”

Instead of relying on a single expensive probe, the device infers groundwater flow using heat. A circuit board equipped with an array of temperature sensors determines the speed and direction of water flow through the soil. The electronic components are housed within a 3D-printed enclosure, which the team designed, printed, and iterated directly in the lab. This cyclical process allows them to modify the hardware within hours without waiting for external manufacturers.

Designing the enclosure proved to be the challenge, as any casing that interferes with water flow would affect measurements. "The key to designing an accurate sensor is to create an enclosure that doesn't interfere with the water flow," Hosen said. "We're using 3D printing to create textures that mimic the soil environment, so water flows over the sensor exactly as it would flow through the soil."

Production is deliberately kept small-scale. The team orders small quantities of parts from U.S. suppliers, and all other processes are completed in-house using 3D printers and a special oven for reflow soldering electronic components. "We just source all the parts from a few U.S. suppliers and then we assemble them ourselves, and it costs only a few hundred dollars per device," Hosen said. "This is not something that most ecological labs can do."

Manufacturing these devices in-house also serves as a teaching tool. Graduate and undergraduate students involved in the project can learn skills such as circuit board assembly, 3D printing, and prototype iteration, which are typically confined to engineering labs rather than the Department of Forestry and Natural Resources.

Durability Test: Eight Months of Underwater Operation

Early durability tests have been the most compelling proof so far: the sensors operated continuously underwater for seven to eight months without failure. If this performance can be maintained at scale, these devices are expected to become standard long-term installations in USGS wells, designed for continuous operation over months or even years, rather than being limited to short-term field work.

Data transmission uses a two-pronged approach. The sensors transmit wirelessly via aLoRanetwork built on campus by Purdue's agricultural IT team, while also writing data to local storage as a backup. This ensures data retention even in remote areas with unstable network connectivity. Purdue is leveraging its expanding LoRa network coverage to test telemetry systems on campus before official deployment.

The first large-scale field test is planned for a USGS site on the Kankakee River near the Illinois border, with other units to be placed in Purdue's ACRE wetlands for hydrological research. Hosen co-developed the concept with Zaven Arra, lead engineer at RRIV; Keith Cherkauer, professor of Agricultural and Biological Engineering and director of theIndiana Water Resources Research Center, serves as co-principal investigator.

New affordable sensor, patent pending. Image courtesy of Purdue University.

 

Its potential uses extend far beyond academic hydrology. Hosen notes it could be used to track contaminated groundwater plumes for the U.S.Department of Defense, monitor the amount of water data centers draw from underground, and assess the stability of buildings in saturated soil. "Anywhere where water is moving underground, it can be applied," he says.

Challenges of Open-Source Hardware in a Closed Market

Purdue University's approach to this patent is key. The application was filed through Purdue's Office of Technology Commercialization not to sell licenses, but to open-source the design, aligning with RRIV's philosophy: a sufficiently dense open-source water quality monitoring platform capable of tracking water quality changes over time. The current gap is structural; effective monitoring is difficult when reference instruments are so expensive that even the USGS can only own a few.

This strategy is not without precedent. In January 2025,researchers at the University of Strathclyde released a £50 open-source 3D-printed microscope, aimed at making lab-grade microscopy accessible to schools, clinics, and labs. Months later,a team from the University of Edinburgh open-sourced the Flex Printer, a sub-£400 machine that can produce fully functional soft robots, with the goal of broadening access to a field long limited by cost and expertise.

Open-source hardware has democratized lab technologies over the past decade. Purdue is betting that the same logic holds true after eight months submerged in a well.

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