Microphysiological systems, or organs-on-chips, that mimic the structure and function of real tissues in vitro, have emerged as an innovative way to study biological processes and drug screening, as well as an alternative to animal testing.

3-D-printed chip measures contractile strength of tissue. However, fabrication requires multistep lithographic processes which prevent rapid prototyping and customization. Data collection is based on labor-intensive microscopy or high-speed cameras.

Harvard University researchers have made what they say is the first entirely 3-D-printed organ-on-a-chip with integrated sensing that overcomes these limitations. Built by a fully automated, digital manufacturing procedure, the 3-D-printed heart-on-a-chip can be quickly fabricated and customized, allowing researchers to collect data for short- and long-term studies (see video).

Six customized viscoelastic, biocompatible and electrically functional materials, or “inks,” are patterned sequentially using 3-D printing. These were designed to be soft and thin enough to flex when engineered cardiac tissue grown on the chip contracts or beats. These movements are translated into resistance recordings by embedded soft strain sensors, which provide continuous electronic readouts of the tissue’s contractile stress.

The chip contains multiple wells, each with separate tissues and integrated sensors. These wells allow researchers to study many engineered cardiac tissues at once. To demonstrate the efficacy of the device, the team performed drug studies and longer-term studies of gradual changes in the contractile stress of engineered cardiac tissues.