Beyond the Battery

All around us but largely invisible, batteries become more ubiquitous every year. Yet with their impact on the environment and the users they serve steadily growing, there has never been a better time to consider whether batteries are the right solution for your next product.

Every year, 1.2 million tons of batteries enter the European Union. These batteries not only have a potentially huge environmental impact but, by requiring perpetual charging or replacement, can also be a burden to the very users they are intended to serve. Nowhere are these factors more significant than in medical devices where production volumes often exacerbate the scale of the environmental impact and where users can rightfully expect the most seamless experience in receiving their treatment free from the need to check and replace batteries in the devices on which they rely.

Batteries Bad?

Modern batteries offer incredible levels of energy storage in almost every conceivable form factor and are available at low cost in high volumes. In the health tech space, batteries form a key component of everything from blood glucose meters to portable ECGs, connected inhalers and autoinjectors. There is however, no escaping the fact that most batteries contain some level of toxic materials. Each battery type is different but as electrochemical devices, they generally rely on a range of potentially hazardous materials including mercury, lead, zinc, cadmium, manganese and lithium. As a result, regulators are increasingly placing responsibilities on the manufacturers of products incorporating batteries to ensure that they minimise the harmful effects of disposal. This has forced manufacturers to consider battery removal as part of a device’s design, but it also requires users to act when it is time for the device to be disposed. For some potential low cost, high volume products, the complexity of implementing a recycling-friendly battery-based design renders them uneconomical.

Cutting Consumption

Reducing our dependence on batteries starts with reducing energy consumption. For decades keeping up with Moore’s law has driven processor manufacturers to double processor power every year. In service of Moore’s law, semiconductor manufacturers have continually driven down silicon feature sizes to the point that the some of the latest chips are built with 7 nm processes. Whilst this trend has enabled enormous increases in processing power, these smaller feature sizes have been combined with features such as dynamic voltage scaling and low power peripherals to deliver huge reductions in the power consumption of processors and sensors.

It’s not just microprocessors and sensors which have received the low power treatment in recent years. E-Paper, cholesteric and Memory LCD displays require exceptionally low or zero static power to operate. Such displays are ideal for battery-less devices or those with very small batteries but can also offer significant usability benefits; an always-on display means that information is always available to the user with no need to wake the display and no tedious start-up times. This opens up a range of opportunities for medical products such as a digital usage instructions which guide the user through correct use of the device through animated graphics.

The Harvest

In 2003 Transport for London launched the RFID based Oyster card as a convenient way to pay for travel on the London Underground. The magic behind the Oyster card was that the card itself contained no power source at all and instead relies on harvesting energy from the ticket barrier when the two were brought together. In 2018 not only are contactless payments ubiquitous, but NFC (a subset of RFID technology) is supported by almost every recent mobile handset. These developments combined with continually dropping power requirements for processors, sensors and displays mean that some devices can harvest sufficient energy from a smartphone or other RFID source to operate with no internal power source at all. Connected devices such as smart inhalers which today rely on lithium batteries and Bluetooth radios could instead communicate wirelessly via RFID and harvest the energy they need in the same process.

Here Comes the Sun

Solar technology has also long been established as a means of powering small electronic devices and as device power consumption has dropped, the efficiency of solar cells has also increased. Related developments such as increasingly sophisticated DC-DC converter controllers which perform Maximum Power Point Tracking (MPPT) mean that small solar cells are now a practical means of harvesting sufficient energy to power simple sensors and radios even in indoor environments.

Dye Sensitized Solar Cells (DSSCs), such as those produced by GCell are well suited to indoor applications and offer an interesting further advantage in that unlike batteries, they are thin and flexible.

If the Sun Don’t Shine?

There is no escaping fact that in some applications, there is no light or radio energy to harvest. Sometimes only a battery will do. In such cases it may be worth considering a growing range of battery solutions which are specifically designed to be easier to recycle. There are many companies pursuing greener solutions to the battery problem and some even come with additional benefits such more flexible form factors. The manufacture of solutions from suppliers such as an Enfucell require far fewer hazardous substances than conventional batteries whilst delivering small amounts of energy in flexible packaging. These characteristics not only make them well suited to unusual form factors, such as in the wearable TempTraq baby temperature monitor, but also make them far more environmentally friendly than conventional solutions.

A promising future for battery-less devices

Whilst batteries are undoubtedly an excellent solution for the power requirements of many portable devices, they also present several environmental, regulatory and usability challenges. With energy harvesting and low power technologies continually evolving, a battery-less design is becoming a viable alternative for an ever-broadening range of devices.

Author: James Holmes, Head of Electronics & Software, KD