Purdue University Develops 3D Printed Groundwater Sensor: Providing a Low-Cost Scientific Instrument Solution for the USGS

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Researchers at Purdue University have developed an open-source, 3D printed groundwater flow sensor, intended as an alternative to the expensive, specialized sensors currently used by the U.S. Geological Survey (USGS). The 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, an assistant professor of IoT and ecological analytics in Purdue’s Department of Forestry and Natural Resources, in collaboration with the open-source hardware non-profit River Restoration Intelligence and Verification (RRIV). Funding was provided by the USGS’s Next Generation Water Observing System (NGWOS), a division dedicated to developing cheaper, faster water resource data collection technologies.

A Sensor You Can 3D Print and "Bake"

Rather than relying on a single expensive probe, the device infers groundwater flow through heat. The circuit board is equipped with an array of temperature sensors that can determine the speed and direction of water flow within the soil. The electronic components are housed inside a 3D printed casing, which the team designed, printed, and iterated in the lab, creating a cycle that allows them to modify the hardware in hours without waiting for external manufacturers.

The design of the housing turned out to be the most difficult part, as any casing that interferes with water flow would affect the measurement results. "The key to designing an accurate sensor is to create a casing that doesn't disturb the water flow," Hosen said. "We are using 3D printing technology to create textures that simulate the soil environment, so that the way water flows through the sensor is exactly the same as how it flows through the soil."

Production scale is intentionally kept small. The team orders small quantities of parts from U.S. suppliers, and all other processes are completed in-house using 3D printers and a specialized oven for reflow soldering of electronic components. "We just procure all the components from a few U.S. suppliers and assemble them ourselves, bringing the cost of each device to just a few hundred dollars," Hosen said. "That is something most ecological laboratories cannot do."

Building these devices themselves 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—skills typically confined to engineering labs rather than departments of forestry and natural resources.

Durability Testing: Eight Months Underwater

Early durability tests are so far the strongest proof: the sensors have operated continuously underwater for seven to eight months without failure. If this performance can be sustained at scale, these devices have the potential to become standard, long-term installations in USGS wells, designed to operate continuously for months or even years, rather than being limited to short-term field operations.

Data transmission uses a two-pronged approach. The sensors transmit wirelessly via a LoRa network set up on campus by Purdue’s agricultural information technology team, while simultaneously writing data to local storage as a backup, ensuring that data is preserved even in remote areas where network connectivity is unstable. Purdue is leveraging its expanding LoRa network coverage to test the telemetry system on campus prior to formal deployment.

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

The new budget-friendly sensor, patent pending. Image courtesy of Purdue University.

Its potential uses go far beyond academic hydrology. Hosen points out that it could be used to track contaminated groundwater plumes for the U.S. Department of Defense, monitor the amount of water extracted from underground by data centers, and assess the stability of buildings in saturated soil. "Wherever there is water flowing underground, it can be useful," he said.

The Challenge of Open-Source Hardware in a Closed Market

Purdue's approach to the patent is key. It was filed through Purdue’s Office of Technology Commercialization, not with the goal of selling licenses, but to open-source the design, which aligns 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; when reference instruments are expensive, such that even the USGS can only own a small number, effective monitoring becomes difficult.

This strategy is not without precedent. In January 2025, researchers at the University of Strathclyde released a £50 open-source 3D printed microscope, designed to make lab-grade microscopes accessible to schools, clinics, and laboratories. A few months later, a team from the University of Edinburgh open-sourced the Flex Printer, a machine costing less than £400 that can produce functional soft robots, with the goal of expanding access to a field long restricted by costs and expertise.

Open-source hardware has popularized laboratory technology over the past decade. Purdue is betting that the same logic still holds true after eight months at the bottom of a well.

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