Small and light
The choice of cell in a battery pack is of fundamental importance. Varta implemented a design in this application using four 18650 lithium-ion cells. Lithium battery types typically offer higher energy density than any other chemistry. In the surgical helmet, Varta has achieved a high capacity of 35Wh in a pack weighing just 225g and measuring 80 mm x 43.7 mm x 41.5 mm.
Battery pack. (Source: Varta)
Withstands harsh conditions
The protective suit completely encloses the surgeon, protecting him or her from particulate matter from the outside. This means that inside the suit, it's hot and humid. The Varta Microbattery battery pack’s sealed plastic enclosure protects it from all external materials -- vapor, contaminants, and liquids. This enclosure must be highly robust, since surgical helmets must be able to withstand rough handling and shock caused when the helmet is accidentally dropped. The special formulation of the plastic renders it highly resistant to shock and vibration.
Predictable power delivery
As a lithium cell discharges, its output voltage gradually drops -- but not in a linear fashion. Simple voltage measurement therefore provides a crude measure of a lithium-ion battery pack’s SoC. The theatre crew, however, requires precise SoC information, so that the remaining run-time can be accurately known, and the risk of unexpected power-down eliminated.
State-of-the-Art theatre equipment
Today’s operating theatres are high-tech environments. The battery pack in a surgical protection helmet relies on the implementation of a number of advanced technologies in the fields of electronics, chemistry, and plastics. Lightweight, small, yet safely providing a high-energy capacity, the lithium-ion power pack solution from Varta Microbattery provides for long, continuous usage. The predictable power it provides maintains a high light output from the headlight and effective ventilation from the five-speed fan, helping to keep the surgeon safe, comfortable, and focused on the task of treating the patient.
Several studies indicate that the noise generated by performing orthopaedic surgery has the potential to cause hearing loss. Noise produced by several orthopaedic surgical instruments such as saws, drills, and hammers during surgery exceeds 100 dB, especially during knee replacement procedures. Surgical protection suit may help to protect surgeon from noise-induced hearing loss.
I like the idea of a display, Greg - that would allow the user to know immediately whether or not the battery should be considered for service without any additional steps. Sounds like a good PIC project to me ;)
Yes, the data chip idea would be nice. Ideally, the charging station would have some type of display which would show the user what percent of charging cycles are left in the battery (and warn if a battery should be replaced soon).
That's a great idea, Greg - from a reliability standpoint they could then discard the battery before it neared the end number of its specified charge cycles - in a critical application such as this that might be a good approach to ensure sufficient battery life. For example - maybe a battery that is spec'ed at 500 charge cycles you could pull it out of service at 400 charge cycles.
It would be really nice to have a data chip in the battery pack that keeps track of the number of cycles and the maximum temperature of the battery pack - that might help you be able to tell when a failure is imminent.
Good point about monitoring remaining run-time to avoid unexpected power-down during operation. Is there also a feature on the charging station which monitors the number of charges each individual battery pack receives? (monitoring charge cycle life).
Truchard will be presented the award at the 2014 Golden Mousetrap Awards ceremony during the co-located events Pacific Design & Manufacturing, MD&M West, WestPack, PLASTEC West, Electronics West, ATX West, and AeroCon.
In a bid to boost the viability of lithium-based electric car batteries, a team at Lawrence Berkeley National Laboratory has developed a chemistry that could possibly double an EV’s driving range while cutting its battery cost in half.
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This discussion will examine what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.