Abstract: A research team from Stanford University has designed and built a new wearable device with stretchable and flexible sensors , which can measure and record a patient’s tumor size in real time by adhering to human skin. Real-time data from the sensors allows researchers to track the immediate pharmacodynamic response of a given drug by continuously recording changes in tumor size, leading to effective treatment.
Assessing treatment effects is a critical issue during tumor treatment, and tools that can monitor changes in tumor size in real time are key to evaluating cancer therapies. Therefore, it is crucial to develop devices that can effectively monitor changes in tumor size. Accordingly, a research team from Stanford University proposed a stretchable tumor volume sensor, which can effectively read the cancer treatment effect of patients.
Utilizing electronic materials, researchers have designed a wearable strain sensor that can measure and record changes in a patient’s tumor volume over time. In a tumor model, the sensor was able to discern the dynamic differences in tumor volume brought about by drug treatment within hours of in vivo treatment initiation. This non-intrusive, battery-powered device is sensitive to even small changes, with results wirelessly streamed to a smartphone app in real-time at the touch of a button. The research results were published in the authoritative journal Science Advances under the title of “A flexible electronic strain sensor for the real-time monitoring of tumor regression”.
Figure 1 Research results (Source: [1])
FAST sensors are fabricated by depositing a 50 nm gold layer on top of a styrene-ethylene-butylene-styrene drop-cast layer, due to its fully flexible and stretchable nature , and thus easily expand or contract as the tumor progresses. For this sensor, when strain is applied, the microcracks in the gold layer lose contact with each other, increasing the tortuosity of the electron path length through the sensor. The relative change in resistance in the sensor spans two orders of magnitude as it stretches from 0% to 75% strain and can detect changes down to 10-micron scale resolution.
A custom-designed printed circuit board and mobile phone app for this sensor provides real-time and historical sensor readings at the push of a button. In addition, the researchers designed a 3D-printed housing mechanism for the FAST sensor to ensure that the sensor and printed circuit board fit properly on the mouse and accurately record tumor volume expansion or contraction.
Fig. 2 Sensor device for measuring changes in tumor volume (Image source: [1])
To verify its ability to discern shape-volume changes in vitro, the researchers measured the output of the sensor when placed on top of a 3D-printed model tumor. They found that the sensor recorded volumes as small as 65mm3 and Significant changes in tumor volume readings up to 750 mm3.
The researchers then again verified the accuracy and validity of the sensor in measuring changes in tumor volume in vivo. In vivo testing in two cancer models showed that the FAST sensor detected statistically significant changes in tumor growth and shrinkage dynamics within 5 hours of treatment in mice compared to mice given the drug or vehicle alone.
The researchers then used erlotinib as an example to evaluate how the FAST sensor measured changes in tumor volume in mice during treatment. The results show that Compared to other measurement techniques that take days to discern biologically significant differences, the FAST sensor can detect changes in tumor volume expansion or contraction almost immediately after drug treatment. During the treatment period, the researchers analyzed the effect of animal movement on the mechanical stress exerted by the sensor and assessed the effect of the mechanical stress exerted by the sensor on the tumor. While wearing the sensor, the animals were able to move, eat and drink freely throughout the study period, and the researchers also confirmed that the sensor had no effect on changes in tumor volume in the mice.
Figure 3 Histology of erlotinib-treated HCC827 tumor confirms that the FAST sensor can rapidly monitor tumor volume changes (Source: [1])
Finally, the researchers characterized the sensor using experimental immunotherapy in a solid tumor model of A20B-cell lymphoma in Balb/c mice to demonstrate that sensor monitoring is effective in multiple tumor models and Accuracy and effectiveness in treatment modalities. Finally, it was found that the sensor can monitor the changes of tumor volume in various tumor models and various treatment modalities.
In response, the researchers said that the tiny device they designed this time, the Flexible Autonomous Sensor for Tumor Measurement (FAST), represents a new, fast, cheap, portable and accurate Ways to test the efficacy of anticancer drugs. In the long term,Such tiny devices could lead to promising new directions for cancer treatment. This monitoring device could not only test the efficacy of anti-cancer drugs accurately, quickly, and portable, but could also significantly reduce the cost of the cancer treatment screening process.
Writing | Mu Zijiu
Typesetting|Feng Lixiao