Measure whether existing devices meet the required order stability

Determine whether fabricated constant-phase devices maintain their fractional order within the ten-percent tolerance associated with acceptable task-performance degradation.

Background

The review reports that only one surveyed device publishes long-term stability data and another publishes capacitance spread; none reports unit-to-unit variability of the fractional order itself. This omission prevents comparison between device variability and the tolerance suggested by task-level experiments.

The stated target is a ten-percent order tolerance, under which Mastin and colleagues observed less than two percentage points of accuracy loss. Measuring whether existing devices satisfy that target is necessary for assessing their suitability as neuromorphic components.

References

Whether existing devices do is unknown, and section~\ref{sec:fabricated} gives a reason to expect the answer to be tight: a $\pm4{\circ}$ in-band ripple, which is the criterion these papers set themselves, is already about half that budget at $\alpha=0.88$, nine tenths of it at $\alpha=0.5$ and more than all of it at $\alpha=0.33$, before any unit-to-unit spread or long-term drift has been measured.

— Fractional-order hardware for neuromorphic computing: Is the order really the problem?  (2609.10882 - Teuscher, 9 Sep 2026) in Section 7.3, “Gaps, stated as questions”; Section 8, item (b)

What nobody appears to have done is to point that instrument at a thin-film fractional-order capacitor and report the result.

— Fractional-order hardware for neuromorphic computing: Is the order really the problem?  (2609.10882 - Teuscher, 9 Sep 2026) in Section 8, “A path forward and a call for action,” item (a)