WebZine
2017.09
What's New
Low-cost wearables manufactured by hybrid 3D printing
By Lindsay Brownell
Posted 6 Sep 2017 | 19:17 GMT
New method combines precision printing of stretchable conductive inks with pick-and-place of electronic components to make flexible, wearable sensors.
Human skin must flex and stretch to accommodate the body’s every move. Anything worn tight on the body must also be able to flex around muscles and joints, which helps explain why synthetic fabrics like spandex are popular in activewear. Wearable electronic devices that aim to track and measure the body’s movements must possess similar properties, yet integrating rigid electrical components on or within skin-mimicking matrix materials has proven to be challenging. Such components cannot stretch and dissipate forces like soft materials can, and this mismatch in flexibility concentrates stress at the junction between the hard and soft elements, frequently causing wearable devices to fail.
Now, a collaboration between the lab of Jennifer Lewis, Sc.D. at the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and J. Daniel Berrigan, Ph.D. and Michael Durstock, Ph.D. at the US Air Force Research Laboratory has created a new additive manufacturing technique for soft electronics, called hybrid 3D printing, that integrates soft, electrically conductive inks and matrix materials with rigid electronic components into a single, stretchable device.
“With this technique, we can print the electronic sensor directly onto the material, digitally pick-and-place electronic components, and print the conductive interconnects that complete the electronic circuitry required to ‘read’ the sensor’s data signal in one fell swoop,” says first author Alex Valentine, who was a Staff Engineer at the Wyss Institute when the study was completed and is currently a medical student at the Boston University School of Medicine. The study is published in Advanced Materials.
The stretchable conductive ink is made of thermoplastic polyurethane (TPU), a flexible plastic that is mixed with silver flakes. Both pure TPU and silver-TPU inks are printed to create the devices’ underlying soft substrate and conductive electrodes, respectively. “Because both the substrate and the electrodes contain TPU, when they are co-printed layer-by-layer they strongly adhere to one another prior to drying,” explains Valentine. “After the solvent evaporates, both of the inks solidify, forming an integrated system that is both flexible and stretchable.”
Medtronic's CardioInsight Electrode Vest Maps Heart's Electrical System
By Emily Waltz
Posted 9 Feb 2017 | 17:00 GMT
Medical device developer Medtronic has commercialized a 252-electrode vest that can map the heart’s electrical system. The device could help doctors pinpoint the locations of electrical malfunctions in the heart that cause irregular heartbeats.
Doctors began using the system commercially last week after the US Food and Drug Administration (FDA) in November approved the vest, Medtronic announced.
Irregular heartbeats, or arrhythmias, are caused by electrical malfunctions of the heart. The malfunctions can bring on a range of problems, from the disconcerting sensation of a fast, irregular heartbeat, to a fatal cardiac arrest.
In order to treat an arrhythmia, doctors must pinpoint the location of the electrical malfunction. That typically involves inserting a catheter with an electrode tip into a blood vessel in the groin, and snaking it up to the heart. By touching the tip to different places on the heart doctors can create spatial and electrical maps.
But those maps are usually incomplete. The catheter can’t reach every part of the heart, leaving some areas of the map blank. The invasive procedure also comes with some risk.
Medtronic’s vest, called the CardioInsight, aims to provide a more complete map—without the snaking groin catheter. The patient puts on the 252-electrode vest and gets into a computed tomography (CT) scanner. The system then creates a three-dimensional electroanatomical map of the heart by combining the vest’s electrocardiogram (ECG) signals and the anatomical image from the CT scan.
