Stretchable electronics

Skin is composed of collagen, keratin, and elastin fibers, which provide robust mechanical strength, low modulus, tear resistance, and softness.

To achieve conformability, it is preferable for devices to match the mechanical properties of the epidermis layer when designing skin-based stretchy electronics.

The aforementioned approach was used to create devices composed of 100-200 nm thick silicon (Si) nano membranes deposited on thin flexible polymeric substrates.

[9] In the case of island interconnect, the rigid material connects with flexible bridges made from different geometries, such as zig-zag, serpentine-shaped structures, etc., to reduce the effective stiffness, tune the stretchability of the system, and elastically deform under applied strains in specific directions.

[7] CMOS inverters constructed on a polydimethylsiloxane (PDMS) substrate employing 3D island interconnect technologies demonstrated 140% strain at stretching.

A study by Li et al. showed a stretchable supercapacitor (composed of buckled SWCNTs macrofilm and elastomeric separators on an elastic PDMS substrate), that performed dynamic charging and discharging.

Stretchable electronics could be integrated into smart garments to interact seamlessly with the human body and detect diseases or collect patient data in a non-invasive manner.

For example, researchers from Seoul National University and MC10 (a flexible-electronics company) have developed a patch that is able to detect glucose levels in sweat and can deliver the medicine needed on demand (insulin or metformin).

The patch consists of graphene riddled with gold particles and contains sensors that are able to detect temperature, pH level, glucose, and humidity.

One way of achieving this is to make an array of conductive OFET (Organic Field Effect Transistors) forming a network that can detect local changes in capacitance, which gives the user information about where the contact occurred.