Tag: medical devices

Categories : Medical Research & Technology OphthalmologyTags :

A Smart Contact Lens Battery Powered by Tears

On By ModernMedia
Photo by Arteum.ro on Unsplash

Singapore scientists have developed a flexible battery as thin as a human cornea, which can store electricity when immersed in a saline solution such as tears. The scientists described their research in Nano Energy, and believe that this technology could one day power smart contact lenses.

Smart contact lenses are high-tech contact lenses capable of displaying visible information on the cornea and can be used to access augmented reality as well as monitoring health and their normal function of correcting vision. But they need power, and existing rechargeable batteries rely on wires or induction coils that contain metal and are unsuitable for use in the human eye, as they are uncomfortable and present risks to the user.

The battery, developed by Nanyang Technological University, is made of biocompatible materials and does not contain wires or toxic heavy metals, such as those in lithium-ion batteries or wireless charging systems. It has a glucose-based coating that reacts with the sodium and chloride ions in the saline solution surrounding it, while the water the battery contains serves as the ‘wire’ or ‘circuitry’ for electricity to be generated.

The battery could also be powered by human tears as they contain sodium and potassium ions, at a lower concentration. Testing the current battery with a simulated tear solution, the researchers showed that the battery’s life would be extended an additional hour for every twelve-hour wearing cycle it is used. The battery can also be charged conventionally by an external power supply.

Associate Professor Lee Seok Woo, from NTU’s School of Electrical and Electronic Engineering (EEE), who led the study, said: “This research began with a simple question: could contact lens batteries be recharged with our tears? There were similar examples for self-charging batteries, such as those for wearable technology that are powered by human perspiration.

“However, previous techniques for lens batteries were not perfect as one side of the battery electrode was charged and the other was not. Our approach can charge both electrodes of a battery through a unique combination of enzymatic reaction and self-reduction reaction. Besides the charging mechanism, it relies on just glucose and water to generate electricity, both of which are safe to humans and would be less harmful to the environment when disposed, compared to conventional batteries.”

The research team has filed for a patent through NTUitive, NTU’s innovation and enterprise company. They are also working towards commercialising their invention.

Cry me a current

The team demonstrated their invention using a simulated human eye. The battery, which is about 0.5 millimetres-thin generates electrical power by reacting with the basal tears – the constant tears that create a thin film over our eyeballs – for the devices embedded within the lenses to function.

The flexible and flat battery discharges electricity through a process called reduction when its glucose oxidase coating reacts with the sodium and chloride ions in the tears, generating power and current within the contact lenses.

The team demonstrated that the battery could produce a current of 45 microamperes and a maximum power of 201 microwatts, which would be sufficient to power a smart contact lens.

Laboratory tests showed that the battery could be charged and discharged up to 200 times. Typical lithium-ion batteries have a lifespan of 300 to 500 charging cycles.

The team recommends that the battery should be placed for at least eight hours in a suitable solution that contains a high quantity of glucose, sodium and potassium ions, to be charged while the user is asleep.

Source: Nanyang Technology University

Categories : Hospitals Implants and ProsthesesTags :

Deaths From Medical Devices Are Underreported in the US

On By ModernMedia
Photo by Vidal Balielo Jr. from Pexels
Photo by Vidal Balielo Jr. from Pexels

Researchers have found that a number of deaths related to medical device adverse events were improperly categorised in the FDA’s Manufacturer and User Facility Device Experience (MAUDE) database, according to a new study.

Flagging terms commonly associated with death, the study investigators used a natural language processing algorithm to identify 290 141 reports where serious injury or death was reported; 52.1% of these events were reported as deaths, and 47.9% were classified as either malfunction, injury, or missing (report was uncategorised), reported Christina Lalani, MD, of the University of California San Francisco, and colleagues, in JAMA Internal Medicine.

Overall, 23% of reports with a death were not placed in the death category, amounting to some 31 552 reports filed from December 31, 1991, to April 30, 2020.

Whether to classify the event as a malfunction, injury, death, or ‘other’ is up to the physician or manufacturer. According to the FDA, the reporter is required to categorise an adverse event as an official death if the cause of death is unknown, or if the device “may have caused or contributed to a death.”

The three most common product codes among the adverse event reports were for ventricular assist bypass devices (38 708 reports), dialysate concentrate for haemodialysis (25 261 reports), and transcervical contraceptive tubal occlusion devices (14 387 reports).

The natural language processing algorithm scanned through reports, identifying terms such as “patient died,” “patient expired,” “could not be resuscitated,” and “time of death.” Of the 70 terms that were associated with a death, 62 (88.6%) were found among miscategorised adverse event reports involving a patient death. And, out of all 62, there were 17 terms that had an estimated percentage of 100%, meaning that “every time that term was used, the patient had died, even though the reporter had not classified the report as death,” the team wrote.

Only 18 terms had sample sizes large enough for researchers to calculate confidence intervals; among them, the words “death” or “deaths” were linked to 12% of adverse event reports in which a patient died, but were classified as malfunction, other, or missing — the highest rate of all the analysed terms.

The researchers acknowledged a major limitation in that only reports with at least one death-associated term were included, in contrast to all the reports from the MAUDE database. Improperly categorised deaths likely contribute to an underestimate.

“The classification chosen by the reporter is vital, as the FDA must review all adverse events reported as deaths, which is not the case for other reporting categories,” the authors wrote. Improving the reports’ accuracy is crucial, since patient death frequency can prompt the FDA to pursue investigations into the device’s safety, they added.

The researchers pointed out an inherent conflict of interest as 95.9% of the reports evaluated in the study were submitted by manufacturers.

“It may not be in their interest to facilitate identification of serious problems with their own devices in a timely manner,” they wrote. “There have been multiple instances of delays by manufacturers in reporting serious malfunctions and deaths that were associated with medical devices, as well as complete failures to report.”

Therefore, it’s likely that a significant number of patients have been unknowingly treated with devices that were later revealed to be dangerous, Dr Lalani and colleagues noted. For example, they referenced the reporting failures that occurred from 2002 to 2013, when 32 000 women reported adverse events associated with the permanent birth control device Essure while the FDA only received 1023 adverse event reports from the manufacturer.

They concluded that patients and care providers should submit reports directly to the FDA as well as or instead of the manufacturer.

Source: MedPage Today

Journal information: Lalani C, et al “Reporting of death in US Food and Drug Administration medical device adverse event reports in categories other than death” JAMA Intern Med 2021; DOI: 10.1001/jamainternmed.2021.3942.