ECE’s Guangyu Xu Obtains Patent for a Cytokine Sensor to Monitor Acute Immune Responses

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Immune-response monitoring is essential in point-of-care applications such as the critical care of patients with acute immune responses. For instance, cytokine-protein monitoring is critical for COVID-19 patients because excessive release of inflammatory cytokines in the blood can be a fatal immune response if not identified in time. Now Associate Professor Guangyu Xu of the UMass Amherst Electrical and Computer Engineering (ECE) Department has patented a pioneering solution for this life-threatening issue. See description of Xu’s patented Spectrally Filtered Photodiode Pair: https://patents.justia.com/patent/12446341.

Cytokines are signaling proteins that play a crucial part in the immune system by enabling communication between cells, among other functions. Xu’s cytokine-sensing device provides an improved sensor with rapid response (< 10 minutes) and a low limit of detection (pM levels). 

According to Xu’s patent description, “The present inventor has advantageously discovered an on-chip ratiometric-aptasensing device to monitor the dynamics of an immune-response biomarker – e.g., interferon-gamma (IFN-γ) – in a label-free manner in real time.”

As the background for Xu’s groundbreaking invention, he says that “Many human-immune responses are associated with cytokine-release syndrome, which needs to be timely identified by biosensors that can offer robust readout. For instance, cytokine monitoring is significant for COVID-19 patients because excessive release of inflammatory cytokines in blood such as interleukin 6 (IL-6), IFN-γ, and C-reactive protein (CRP) can be a fatal immune response if not timely identified and needs to be closely monitored during the clinical treatment or vaccine development.”

Xu explains that “A cytokine biosensor should: 1) be miniaturized for integration purposes; 2) record cytokine dynamics in a label-free manner; and 3) feature crucial attributes such as low limit-of-detection, low drift, and high specificity. Yet, these requirements have not been simultaneously met in existing sensing technologies.” 

To overcome these limitations, says Xu, “The ratiometric-aptasensing strategy, in which the aptamer-cytokine-binding events are quantified by the fluorescence ratio of donors and acceptors in a Förster resonance energy transfer (FRET) pair, has been recognized for its label-free operation, reduced baseline drift, and fewer device-to-device variations. If such sensing strategy can be achieved in devices with compact optical readout, cytokine dynamics can be monitored in a miniaturized point-of-care testing system, which will in the long term make an impact for personalized medicine.”

Xu’s patented invention accomplishes all these functions. “To enable miniaturized ratiometric aptasensing,” he explains, “one pair of photodetectors should be placed next to each other, ideally built in a chip scale, and integrated with distinct on-chip spectral filters to detect the emission light of select donors and acceptors. To achieve this, the two on-chip filters need to be site-selectively patterned onto each of the two photodetectors.” 

Xu adds that, to assure high-wavelength selectivity of the device, the transmittance spectra of these two filters need to feature low-optical crosstalk to each other, high rejection of the targeted excitation light, and high transmittance of the targeted-emission light.

Xu heads the Integrated Nanobiotechnology Laboratory. As he says. “Here we build miniaturized cell interfacing and biosensing tools, aiming to offer new capabilities for important biomedical applications. With an affinity for diverse areas in nanodevice, bioelectronics, cell imaging, and optoelectronics, we enjoy the bandwidth our work spans over and the problem-oriented way of thinking.” Xu is also an adjunct in the Biomedical Engineering Department. (February 2026).