Many types of devices are available in smaller, sleeker shapes, which require their internal electronics to flex, bend, and stretch as they do. The ability for circuits to stretch and bend allows them to fit into spaces where rigid printed circuit boards cannot. Flexible circuits also offer the advantage of being thinner and lighter, and examples of these can currently be found in implantable devices such as pacemakers, defibrillators, and cochlear implants.
There has been a steady increase in patent filings since 2013 with regard to “smart clothing” (clothing that monitors the wearer’s physical condition, providing biometric data such as pulse rate, temperature, muscle strength, heart rhythm and physical movement). Industrial facilities are looking to adopt smart clothing as a way to improve workers’ efficiency, and both professional and casual athletes are looking for tools to monitor and record their workouts and progress. Additionally, developers are seeking better ways to incorporate electronics into clothing to help monitor the daily activities of many kinds of potential users- from young children to the elderly- for both health and safety information.
STRETCHABLE POLYMER-BASED ELECTRONIC DEVICE (IL11206, US Patent 7,337,012)
This invention has a central longitudinal axis and is a stretchable polymer body in a longitudinal direction. Within the polymer is a circuit line extending in the longitudinal direction with an offset component that is at an angle to the longitudinal direction, forming a serpentine shaped circuit, allowing the device to stretch while maintaining the integrity of the circuit.
Current wearable technology challenges include design, easy accessibility, advanced sensors (with functions such as low power, ease of use, robustness, and integration with existing systems), user-friendly interfaces, lightweight devices, data security concerns, and high cost.
The LLNL lightweight stretchable design allows for close contact with the wearer or its environment, leading to a more consistent signal. The stretchable circuit can conform to both external (i.e., legs, neck, arms) and internal (i.e., neural, spinal, cochlear) body surfaces. The robust, biocompatible, stretchable polymer body composed of polydimethylsiloxane (PDMS) can be made in batch processes and provides a low-cost device that is ready for long-term implantation or wearing without the need for additional packaging steps.
This innovation could find use in the rapidly-expanding wearable electronics segment, as the integrity of the circuit would not be compromised when it follows the curvature and movement of the human body. Wearables can be used for worker identification based on biometric scanners, ensuring only the authorized worker has access to valuable information. Additionally, unobtrusive wearables, such as smart gloves and hats, could be used to monitor the level of harmful chemicals in a hazardous workspace.
There are also numerous other potential applications for stretchable circuits, including: shaped acoustic sensors and transmitters; biological, chemical, temperature, and radiation sensors; sensors and stimulators for interfacing with human body and inanimate objects; epiretinal, subretinal, and cortical artificial vision implants, cochlear implants, neurological implants, spinal cord implants and other neural interface implants; implantable and transdermal drug delivery devices; monitoring devices; implantable ribbon cables and electrode array for DBS, spinal cord reattachment, nerve regeneration, drug delivery; and muscle stimulation & relaxation.