When it comes to 3D printing, the sky is the limit. As 3D printing technology continues to advance, applications can be as far reaching as airplane and automobile parts to medical devices and even anatomically correct, biocompatible models. Although 3D printing technology is developing at a rapid pace, the technology itself is not new. It emerged in the 1980s as a means of creating rapid prototypes. In recent years the applications for 3D printed models have evolved with the available hardware, software, and printable materials. Evolving technology, paired with the creative and innovative minds of scientists, engineers, and physicians, has been the launching pad for developments within 3D printing technology specific to healthcare. One way 3D printing technology is poised to create better patient outcomes is in creating an anatomically and patient-specific models to aid in surgery and medical procedures. With the capability to 3D ...
Wearable electronics concepts and designs often exceed our wildest imagination, from stick-on electronics circuits that are flexible enough to wrap around the hair, to the next step: stretchable and twistable working electronic monitors!
Elasticity, i.e., the ability of a material to return to its original shape after deformation, is an inherent property of many living systems, including human skin. Wearable electronics have to mimic the property of skin as closely as possible. Polymers provide a perfect answer to the need of soft sensors and electronics to be flexible. Previously explored concepts included porous polymer elastomers containing liquid metals as stretchable electrode materials.
Stick-on Heart Monitor
Now a totally different approach has been designed and tested in a working prototype of a stick-on heart monitor. An international team of 18 scientists led by Dr. John Rogers of the University of Illinois at Urbana-Champaign used the concept of soft microfluidics to design a technology to create highly stretchable devices using functional rigid electronic components. The article, published in Science, explains:
The most well-developed component technologies are […] broadly available only in hard, planar formats. As a result, existing options in system design are unable to effectively accommodate integration with the soft, textured, curvilinear, and time-dynamic surfaces of the skin. Here, we describe experimental and theoretical approaches for using ideas in soft microfluidics, structured adhesive surfaces, and controlled mechanical buckling to achieve ultralow modulus, highly stretchable systems that incorporate assemblies of high-modulus, rigid, state-of-the-art functional elements. The outcome is a thin, conformable device technology that can softly laminate onto the surface of the skin to enable advanced, multifunctional operation for physiological monitoring in a wireless mode.
The beauty of the idea is that the electronic components are enclosed inside a thin elastomeric hollow structure filled with a dielectric fluid. Each electronic component is gently attached to the bottom of the enclosure through a “support post.” While the components are mechanically isolated from each other, they are connected electrically by a free-floating network of serpentine-shaped interconnects, which can stretch in a coil-like manner. In their model system, the scientists used silicone elastomer for the substrate and high molecular weight silicone oligomer for the dielectric fluid.
The soft microfluidic electronic assembly successfully withstood 100% biaxial strain and remained fully functional. In response to external deformation, the free-floating connectors can deform with little constraint. This video demonstrates a stretchable electrocardiogram (ECG) device, which wirelessly transfers power, senses electrophysiological potential and transmits data wirelessly to the external receiver. By placing an inductive coil near the secondary coil in the device, the ECG signal is amplified, filtered, and wirelessly transmitted to a receiver and recorded in real time.
Wide Range of Sensors
The quest for soft sensing systems is ongoing, fueled by dreams of seamless prostheses, wearable electronics, and advanced human-machine interactions. Recent flexible and stretchable pressure and touch sensors and stretchable antennas made with silver nanowires are exciting developments, as are previously reviewed (pdf) soft embedded sensors. Curvature sensors can be used to capture motion, and shear sensors are needed to develop functional robotic hands. Above all, autonomous sensors do not need any source of power and transmit data wirelessly, allowing for long-term wearable and implantable electronics. Now, with electronics becoming flexible and stretchable, application horizons are broadening even more, possibly extending an area traditionally occupied by medical devices into fun (and useful) gadgets for everyone.
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