Physical Silver: Four Cases Of Industrial Advances

This article details several cases in which silver helps several industry types in making advances: agriculture, health and electricity. This is an excerpt from the latest newsletter released by The Silver Institute.

Silver Ink Makes Low Cost Agricultural Sensor Possible

SenSprout, a leaf-shaped sensor that allows farmers to remotely measure rainfall and soil moisture levels, uses silver inks to produce printed circuit board sensors at low cost.

Current water sensors cost over US$100 without monitors or data loggers, according to the company’s founder, Kazuhiro Nishioka. The SenSprout sensor costs less than half, not only because of the inexpensive printed circuit board construction but also because it connects to an app on a smartphone. No additional equipment is necessary.

Due to the use of printing technology, SenSprout can be manufactured at low cost in mass production and in small lots, company officials say. The sensor is solar powered so there is no battery replacement and no danger of leakage into the soil.

The SenSprout sensor was recently shown at SXSW (South by Southwest Conferences & Festivals), where company officials said that they hope to produce a sensor that will not only check soil moisture but nutrients, too.

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Tiny Battery May Help Implant Release Antibacterial Silver Ions on Cue

Medical investigators for several years have been testing the ability of silver ions in implants to ward off infections (See Silver Tested in Bone Implants, Silver News, June, 2014). Now, researchers at the North Carolina State Department of Industrial and Systems Engineering have taken it to the next level. They are studying ways to apply a low-intensity electrical charge to a silver-titanium implant to increase the release of silver ions, thus giving the implant greater antibacterial power.

The power source, researchers suggest, could be a button-type battery, similar to a watch battery, which is integrated into the implant.

In tests, the implant showed a 99 percent drop in bacteria around the implant after 24 hours. After 48 hours, the area around the implant was bacteria free. The researchers, Assistant Professor Rohan Shirwaiker and doctoral candidate George Tan, are exploring the use of a smartphone app to control the battery and thus the release of silver ions.

In 2014, Shirwaiker, an engineer by training, was awarded the Best Young Investigator Research Poster Award at the American Academy of Orthopedic Surgeons (AAOS) — Orthopedic Research Society Conference on musculoskeletal infections.

More than a million joint replacement surgeries are performed annually in the United States and infection control has always been an issue to which physicians pay close attention, because the cure can require surgery and long-term treatment with antibiotics. “Prosthetic joint infection (PJI) remains one of the most serious complications of prosthetic joint implantation,” according to guidelines from the Infectious Diseases Society of America (IDSA). “The management of PJI almost always necessitates the need for surgical intervention and prolonged courses of intravenous or oral antimicrobial therapy.”

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Static Electricity May Power Wearables

As we move into the age of ‘wearables’ such as the new Apple Watch, the question arises as to how to power these devices. Batteries wear out and add weight, but what if we could power our wearables with the same power jolt that we get from walking across the carpet and touching a light switch?

Researchers in South Korea and Australia are harnessing the power of triboelectricity, the technical term for static electricity, which occurs when two different materials rub against each other and then separate. In the separating process, one material steals electrons from the other – the spark that we feel from our fingertips – but harnessing this tiny amount of electricity is tricky.

The mechanism is a pliable layer of two fabrics, one coated in silver and the other in silver, zinc oxide nanorods (100 nanometers wide and 1 micron long) and silicon rubber. When several sandwich layers are stacked and pressed together, they produce 170 volts and 120 microamperes, which may sound like a lot of voltage but the amount of current or amperes is extremely small. The power output is a little more than 1 milliwatt, which is enough to power about six light emitting diodes (LEDs) and a keyless remote entry for a car.

In testing, the fabric has withstood more than 12,000 cycles of compression and release.

Writing in the journal Nano, the authors note: “In recent years, the field of wearable electronics has evolved at a rapid pace, requiring continued innovation in technologies in the fields of electronics, energy devices, and sensors. In particular, wearable devices have multiple applications in healthcare monitoring, identification, and wireless communications, and they are required to perform well while being lightweight and having small size, flexibility, low-power consumption, and reliable sensing performances.”

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Fogger With Silver Ion Formula Fights MRSA

A U.S. company fogged a house with a formula that includes hydrogen peroxide and silver ions in order to rid the residence of the antibiotic infection known as Methicillin-resistant Staphylococcus aureus, or MRSA, that had sent the family’s 5-month old to the hospital — where he spent almost two weeks on a ventilator before being discharged.

The company, Sanosil International, treated the house for free as a precaution after being brought in by a family friend. “Hydrogen peroxide has long been used as an anti-microbial agent,” the company notes in its technical literature. “The Sanosil formula contains hydrogen peroxide, which, in conjunction with other proprietary raw materials, is converted into an entirely new material. So, while basic hydrogen peroxide had limited killing mechanisms, efficacy and stability. Sanosil is a multi-mechanistic, extremely stable, broad-spectrum product.”

This is the first time Sanosil has disinfected an entire house for MRSA, said David St. Clair, chairman of the company. The system is more commonly used to fight mold. A MRSA cleaning of this type would cost between US$2,000 and US$3,000, St. Clair told Delawareonline.com. “It is the only fogging system in the U.S that is approved by the EPA,” he said. “EPA approval is very, very important. You had to prove efficacy and safety and that remains very important in the health care market.”

When used on surfaces, Sanosil Disinfectant requires no rinsing. Sanosil itself decomposes into water and oxygen and contains no chlorinated or brominated ingredients, he said.

The company’s Halo Disinfection System uses a portable fogger a little taller than a kitchen trash receptacle. It is mostly used in doctor’s offices and medical facilities, and was used in Nigeria during the Ebola epidemic to curb the spread of infection, company officials said.

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