Science Concentrates ELECTRONIC MATERIALS
Breathable electronic skin Nanomesh design allows airflow through skintight, stretchable gold electronics
C R E D I T: TA KAO S OM E YA GRO U P/ U OF TOKYO ( H A N D S )
Electronics designed to stick to skin and transmit the body’s electric signals could improve the sensitivity of prosthetics or help doctors monitor patients’ vital signs. Unfortunately, conventional electrodes used for this purpose trap air and sweat against skin, causing irritation or inflammation when used for an extended period. Now, a team of researchers from the University of Tokyo, the Japan Science & Technology Agency, and Riken have developed a conductive gold nanomesh that is flexible and breathable while relaying electric signals (Nat. Nanotechnol. 2017, DOI: 10.1038/nnano.2017.125). To make the material, researchers led by Takao Someya at the University of Tokyo electrospun nanofibers of biocompatible polyvinyl alcohol (PVA) and interwove them to form a mesh. They then coated the top of the nanomesh with a layer of gold 70- to 100-nm thick. After applying this mesh to a person’s skin, researchers sprayed it with water to dissolve the PVA and form an adhesive layer several tens of nanometers thick to hold the gold conductors in place. A person can easily remove the nanomesh in the shower or bath because the PVA is very water soluble. The nanomesh easily conformed to skin irregularities, fingerprints, and wrinkles,
and was both gas and water permeable. A panel of 18 participants rated the nanomesh Gold nanomesh conducts as more comfortable than an electric current from conventional plastic and elasa flexible battery placed tomer films used as electrode near the knuckle to a lightadhesives. The nanomesh also emitting diode just below the caused no clinical signs of skin fingernail. irritation after participants And although the nanomesh wore it for one week. did not outperform convenDespite its thinness, the tional gel electrodes in renanomesh was flexible enough cording electromyograms, she to retain function when says the nanomesh was still stretched repeatedly to 40% able to detect a comparable of its original length—about A gold nanomesh as much as the skin on your conductor placed on signal. Someya and the study’s coknuckle stretches when going a hand. lead author, Akihito Miyamoto, from straight to bent. The think the nanomesh has two major applicaresearchers successfully used the nanotions. “The first is long-term monitoring of meshes to relay electric signals from tiny patient vital signs without causing any stress fingertip sensors for touch, temperature, and pressure to a fingerless glove capable of or discomfort,” Miyamoto says. “The second wirelessly transmitting the data to a laptop. is the continuous, precise monitoring of athletes’ physiological signals and motions The nanomesh could also perform elecwithout impeding their performance.” tromyogram recordings directly from skin, Someya thinks reducing the nanomesh’s detecting the electric signals from a flexing cost—possibly by replacing gold with a muscle. different, less costly conductor—could Zhenan Bao, a chemical engineer at yield disposable sensors that would easily Stanford University, says the nanomesh’s be replaced during long-term monitorbreathability and the way it conforms to ing.—EMMA HIOLSKI skin are the material’s main advantages.
ANALYTICAL CHEMISTRY
Proton mass (amu)
The proton gets weighed again
1997
The proton may be significantly lighter than currently believed—1.007276466583 amu compared with 1.007276466879 amu—reports a group led by physicist Sven Sturm of the Max Planck Institute for Nuclear Physics (Phys. Rev. Lett. 2017, DOI: 10.1103/PhysRevLett.119.033001). A lower proton mass could affect the values of physical constants such as the Rydberg constant, which represents the lowest-energy photon that can ionize a hydrogen atom from its ground state. The scientists used a Penning trap, which holds a proton in a combination of magnetic and electric fields. The frequency at which the proton orbits in the magnetic field is proportional to its charge-to-mass ratio.—JYLLIAN
KEMSLEY
1999 2002 2008 2014 2017
1.0072764660 1.00727646689 1.00727646686 1.00727646695 1.007276466879 1.007276466583
Sources: H. Borgenstrand, Ph.D. thesis, Stockholm University, 1997; AIP Conf. Proc. 1999, DOI: 10.1063/1.57450; Phys. Scr. 2002, DOI: 10.1238/Physica.Reg ular.066a00201; Phys. Rev. A 2008, DOI: 10.1103/PhysRevA.78.012514; International Council for Science Committee on Data for Science & Technology, 2014; Phys. Rev. Lett. 2017, DOI: 10.1103/PhysRevLett.119.033001 JULY 24, 2017 | CEN.ACS.ORG | C&EN
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