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Researchers Boost Biosensor Sensitivity with OECT-Fuel Cell Integration

A team of researchers at Rice University has developed a new method to significantly enhance the sensitivity of enzymatic and microbial fuel cells using organic electrochemical transistors (OECTs). This advancement could help to lay the groundwork for the next generation of biosensors in medicine, environmental monitoring, and wearable technology.

Biotechnology concept.

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The new approach amplifies electrical signals by up to three orders of magnitude while improving signal-to-noise ratios. This breakthrough allows for highly sensitive, low-power biosensors that could detect biomolecules and contaminants with greater precision than ever before.

We have demonstrated a simple yet powerful technique to amplify weak bioelectronic signals using OECTs, overcoming previous challenges in integrating fuel cells with electrochemical sensors. This method opens the door to more versatile and efficient biosensors that could be applied in medicine, environmental monitoring, and even wearable technology.

Rafael Verduzco, Professor and Study Corresponding Author, Chemical and Biomolecular Engineering and Materials Science and Nanoengineering, Rice University

Conventional biosensors rely on direct interactions between biomolecules and the sensor device, often limiting their effectiveness in incompatible electrolyte environments. The Rice team addressed this challenge by electronically coupling fuel cells with OECTs rather than introducing biomolecules directly into the sensor.

One of the biggest hurdles in bioelectronic sensing has been designing systems that work in different chemical environments without compromising performance. By keeping the OECT and fuel cell separate, we ensured optimal conditions for both components while still achieving powerful signal amplification.

Caroline Ajo-Franklin, Professor and Study Corresponding Author, Biosciences, Rice University

Ajo-Franklin is also the Director of the Rice Synthetic Biology Institute and Cancer Prevention and Research Institute of Texas Scholar.

OECTs are thin-film transistors designed to operate in aqueous environments, gaining attention for their high sensitivity and low-voltage operation. In this study, the researchers integrated OECTs with two types of biofuel cells to enhance their performance.

The first type, enzymatic fuel cells, used glucose dehydrogenase to catalyze glucose oxidation, generating electricity in the process. The second type, microbial fuel cells, were reliant on electroactive bacteria to metabolize organic substrates and produce current. The team explored two configurations for coupling OECTs with these fuel cells: a cathode-gate configuration and an anode-gate configuration.

Their findings showed that OECTs can amplify signals from enzymatic and microbial fuel cells by factors ranging from 1000 to 7000, depending on the configuration and fuel cell type—far surpassing traditional electrochemical amplification techniques, which typically achieve signal enhancements of 10 to 100 times.

Among the configurations tested, the cathode-gate setup delivered the highest amplification, particularly when a specific polymer was used as the channel material. While the anode-gate configuration also demonstrated strong amplification, it presented challenges at higher fuel cell currents, sometimes leading to irreversible degradation.

Beyond signal amplification, the researchers found that OECTs helped reduce background noise, improving measurement precision. Traditional sensors often struggle with interference and weak signals, but OECTs provided clearer, more reliable data.

We observed that even tiny electrochemical changes in the fuel cell were translated into large, easily detectable electrical signals through the OECT. This means that we can detect biomolecules and contaminants with much greater sensitivity than before.

Ravindra Saxena, Study Co-First Author and Graduate Student, Applied Physics Program, Smalley-Curl Institute, Rice University

The potential applications for this technology are extensive. To demonstrate its scalability, the research team successfully miniaturized the system onto a single glass slide, proving its viability for portable biosensors.

One of the most promising uses is arsenite detection—a crucial advancement for water safety. The team engineered E. coli bacteria with an arsenite-responsive extracellular electron transfer pathway, allowing them to detect arsenite at concentrations as low as 0.1 micromoles per liter. The OECT-amplified signal provided a clear, measurable response, making this a highly sensitive detection method.

Beyond environmental monitoring, this system has exciting implications for wearable health technology, where power-efficient and highly sensitive biosensors are in high demand. For instance, the researchers demonstrated lactate sensing in sweat—a key indicator of muscle fatigue—using microbial fuel cells, highlighting the system’s potential for real-time health monitoring.

Athletes, medical patients, and even soldiers could benefit from real-time metabolic monitoring without the need for complex, high-power electronics,” said Co-First Author Xu Zhang, a Postdoctoral Fellow in the Department of Biosciences.

The researchers highlighted the importance of understanding the power dynamics between OECTs and fuel cells to optimize sensor performance. They identified two distinct operational modes.

In the power-mismatched mode, the fuel cell generates less power than the OECT requires, leading to higher sensitivity but operating closer to short-circuit conditions. Conversely, in the power-matched mode, the fuel cell produces enough power to drive the OECT, resulting in more stable and accurate readings.

Verduzco said, “By fine-tuning these interactions, we can design sensors tailored for different applications, from highly sensitive medical diagnostics to robust environmental monitors. We believe this approach will change how we think about bioelectronic sensing. It is a simple, effective, and scalable solution.”

The study was funded by the Army Research Office, the Cancer Prevention and Research Institute of Texas, and the National Science Foundation.

Journal Reference:

Saxena, R., et al. (2025) Amplification of enzymatic and microbial fuel cells using organic electrochemical transistors. Device. doi.org/10.1016/j.device.2025.100714.

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