This seems to be a more usual way of putting it:

"Internal indicators [sic] strips
[...]
Internal Indicator Strips are placed in each pack, wrapped tray, container system,pouch and any other items to be sterilized. The internal indicator strip should provide an indication that sterilization conditions were achieved within the pack at the location of the instrumentation."
[...]
Table 1:
Tolerances for the stated values of the critical variables necessary for ethylene oxide sterilization.
Class of Internal
Indicator Strip [...]"
http://www.hpnonline.com/ce/pdfs/1411cetest.pdf

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Note added at 32 mins (2016-02-03 20:06:16 GMT)
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"Control" and "indicador" are effectively the same in this context:

"Control químico: Cinta indicadora (indica solo si ha pasado por un proceso de esterilización). Tira de control interno o baliza se colocan en el interior y exterior de las cajas."
Guía para el manejo del autoclave en la central de esterilización
del Hospital Universitario de Ceuta
http://www.ingesa.msssi.gob.es/estadEstudios/documPublica/in...

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Note added at 1 hr (2016-02-03 21:03:26 GMT)
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I don't mean that "control" and "indicator" are synonyms, but simply that Spanish and English express the same thing differently: the strips contain an indicator which enables them to serve as a control.