Protecting medical products against Electrostatic Discharge (ESD)

E-health applications bring new challenges for reliability.

  • Semiconductors are inserted and integrated in novel locations (in/on the body, in clothes,…) without the system/board level protection typically used in consumer electronics.
  • Replacing or repairing a failed system can be very expensive when it is implanted in the body so reliability is very important.
  • Moreover, the probability of ESD stress is much higher in those systems as they are operated in so-called harsh environments. Consider that plastic (e.g. patch, wearable) rubbed by cloth (your clothes) generates a lot of charges. For many medical applications the environment for the IC is less predictable and certainly harsher as compared to consumer electronics like TVs or desktop computers.
  • Every innovative medical system needs to communicate with its surroundings or directly with internet. Therefore wireless interfaces can be found on almost all of the systems. For those interfaces the IC designer needs on-chip ESD protection with low parasitic capacitance (200fF or lower). Most of the general purpose interface circuits provided by the foundry are not suitable.
  • Due to the SoC integration analog experts and ESD designers must work together more closely. The voltage level required for many sensor applications is higher than the voltage level available in the chip. Other applications require small signals (order of a few mV or mA) that remain hidden in the noise or are lost due to leakage created by General Purpose Input Output circuits (GPIO).

Traditional ESD solutions are not suited for these challenges. There is a need for innovative ESD solutions. In the past, several medical IC design companies have relied on Sofics for the protection of their custom analog designs against Electrostatic Discharge events. Sofics’ flexible on-chip ESD protection portfolio already protects a broad range of applications in more than 3000 IC designs from 80+ customers.

Hearing aid cochlear implant
Image source: Wikipedia

Sofics provides custom ESD solutions that complement and out-perform the foundry provided ESD clamps: higher ESD performance, lower leakage, latch-up safe, lower capacitance, smaller area, high voltage tolerant. ESD clamps with low leakage can enable a longer battery life or simplify energy harvesting constraints. ESD clamps with low capacitance enable wireless or high speed communication.

Sofics solutions were used for these e-health cases in the recent past

Implanted hearing device.

  • ESD protection level of 6kV HBM required for the high voltage pins
  • High voltage tolerant pins up to 18V, for stimulation
  • Ultra-Low leakage of 10pA @ 37°C for the ESD clamps

Hearing aid (external) application

  • 130nm process
  • Analog domain protection
  • 3.3V signals using sensitive 1.2V transistor circuits – Narrow ESD design window

 

Sofics has ESD clamps verified in 10 CMOS generations, down to 16nm FinFets and on various high voltage and BCD processes. Contact Sofics if you want to discuss your own project.

 

 

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