On choosing touchscreen displays and ensuring IEC 60601 compliance

H

HenryC

One of our products will need a touchscreen for interaction with surgeons and nurses in an intraoperative setting. The screen will be installed inside the main enclosure and only the touch sensitive display area will be accessible. We are looking into displays in the 10inch to 15inch range.

At this point we are trying to source the screen and decide whether resistive or capacitive is the way forward for adequate functionality but also for un-eventful 60601 compliance and safe operation (e.g. with respect to ESD testing).

In a past Elsmar's thread it was mentioned that a specific capacitive TFT could not cope with ESD tests, and the question was raised whether this was a general problem with capacitive displays, suggesting that perhaps resistive would be more appropriate for a medical product (in our case intraoperative). The thread did not reach a conclusion on this.

In addition to looking for IEC 60601-certified TFTs we are also studying the possibility of using a regular touchscreen TFT, and then certify the entire product.

Any advice? Should we right away discard the possibility of using a regular TFT and then certify the entire product, are we missing something obvious against this strategy?

Any insight on capacitive vs resistive?

Thank you in advance for your advice.
 

siping21c

Registered
Personally thought ESD shouldn't be a problem. Touch screen like phone, iPad, in daily use can subject to much higher discharge voltage. Most problem can happen is the discharge at somewhere close to screen edge where glass top doesn't cover and the e field intereference to data transmission. Also, you may consider the environment the screen to be used such as if liquid may drop on screen causing mis-touch action.
 
H

HenryC

Thanks.

It would be great to hear from our colleagues about past experience and issues encountered with 60601-1 certification of MEs including non-certified touchscreens.

And most importantly whether any clause in the standards or in-the-job experience suggests this is not a good approach in the context of 60601-1.
 

siping21c

Registered
Also, it's depend on how important (reliable) the touch screen shall be. If screen failure is acceptable, it's not a problem. However, if screen failure may introduce unacceptable risk (e.g. screen not response to touch action and cause over dose of drug devilry), another means of stop over devliery may be required, such as a manual switch or automatic shut off and alarm.

Trying to think more, however it's really depending on your application and detailed usage of the screen for.
 

Mark Meer

Trusted Information Resource
...In a past Elsmar's thread it was mentioned that a specific capacitive TFT could not cope with ESD tests, and the question was raised whether this was a general problem with capacitive displays, suggesting that perhaps resistive would be more appropriate for a medical product (in our case intraoperative). The thread did not reach a conclusion on this.
...
Any advice? Should we right away discard the possibility of using a regular TFT and then certify the entire product, are we missing something obvious against this strategy? ...

We've had some 60601 ESD "surprises" in the past with certain components, and now mitigate by having items get tested informally during development.

Process was something like this:
1. Identify the 60601 clauses that could potentially be an issue with the component*
2. Source a test lab that is willing to do just that test. To cut costs we:
2(a). Don't rule out labs based on accreditation for these preliminary tests
2(b). If approaching the test lab that will ultimately be doing the final 60601 testing, we have found that we can often negotiate discounts if we've already committed to eventual 60601 testing.

*I'm not part of engineering/design, so unfortunately can't give any more details.

Bottom-line: there may be a limited number of (relatively inexpensive) preliminary ESD tests you can do if you're concerned that a particular component (e.g. capacitive displays) may be problematic as per 60601 requirements.
 

Miner

Forum Moderator
Leader
Admin
Will a capacitive touchscreen work when the user is wearing latex or nitrile gloves? My industry (not medical) uses resistive touchscreens because the primary users wear work gloves, which will not activate a capacitive touchscreen.
 

VinceTech

Involved In Discussions
Will a capacitive touchscreen work when the user is wearing latex or nitrile gloves? My industry (not medical) uses resistive touchscreens because the primary users wear work gloves, which will not activate a capacitive touchscreen.

we have seen is some cap touch screens do work with latex gloves, however some not or not sensitive enough. It maybe affected by the top glass too.
 
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