Engineers from Stanford University have created a small, autonomous device with a stretchable and flexible sensor that can be adhered to the skin to measure the changing size of tumors below. The non-invasive, battery-operated device is sensitive to one-hundredth of a millimeter (10 micrometers) and can beam results to a smartphone app wirelessly in real-time with the press of a button.

In practical terms, the researchers stated that their device, dubbed FAST for "Flexible Autonomous Sensor Monitoring Tumors," represents a wholly new, fast, inexpensive, hands-free, and accurate way to test the efficacy of cancer drugs. The researchers stated that every year, thousands of potential cancer drugs are tested on mice with subcutaneous tumors, out of which only a few make it to human patients. The inherent biological variation of tumors, the shortcomings of existing measuring approaches, and the relatively small sample sizes make drug screenings difficult and labor-intensive. Dr. Alex Abramson, the first author of the study, currently a postdoc student in Chemical Engineering at the Stanford School of Engineering, further noted that in some cases, the tumors under observation are measured by hand with calipers.

He added that FAST can detect changes in tumor volume on a minute-timescale, while caliper and bioluminescence measurements often require weeks-long observation periods to read out changes in tumor size. The article published in Science Advance stated that the FAST’s sensor is composed of a flexible and stretchable skin-like polymer that includes an embedded layer of gold circuitry. This sensor is connected to a small electronic backpack that measures the strain on the skin membrane, such as how much it stretches or shrinks, and transmits that data to a smartphone. Using the FAST backpack, potential therapies that are linked to tumor size regression can quickly and confidently be excluded as ineffective or fast-tracked for further study. 

(Source: https://news.stanford.edu/2022/09/16/new-wearable-device-measures-changing-size-tumors-skin/ )