Table 2.

Summary of array time in vivo, processing techniques, and SEM imaging results.

Array name	Time in vivo	SEM prep	SEM findings
Control 1	N/A	No fixation, critical point dryer, Au/Pd coating	Tips: No platinum degradation; minimal parylene delamination.
			Shafts: No cracks in parylene, rare parylene irregularities.
			Base: No cracks in parylene, rare parylene irregularities.
			Edges: No silicone deposited, no cracks in parylene or silicon.
Control 2	N/A	NaCl × 1 wk, critical point dryer, Au/Pd coating	Tips: No platinum degradation; minimal parylene delamination.
			Shafts: No cracks in parylene, rare parylene irregularities.
			Base: No cracks in parylene, rare parylene irregularities.
			Edges: No silicone deposited, no cracks in parylene or silicon.
Control 3	N/A	NaCacodylate × 1 wk, critical point dryer, Au/Pd coating	Tips: No platinum degradation; minimal parylene delamination.
			Shafts: No cracks in parylene, rare parylene irregularities.
			Base: No cracks in parylene, rare parylene irregularities.
			Edges: No silicone deposited, no cracks in parylene or silicon.
LN- LSMA	37 days	NaCacodylate fix, ethanol, critical point dryer, Au/Pd coating	Tips: No platinum degradation; thin tissue encapsulation (~250 nm); no parylene delamination.
			Shafts: Thin uniform tissue encapsulation with many fibroblasts; few cracks in parylene.
			Base: Many active macrophages and fibroblasts; occasional shallow cracks in parylene.
			Edges: No silicone delamination, no cracks; no tissue adhesions or cells on silicone.
SCT-RV1	99 days	NaCacodylate fix, ethanol, critical point dryer, Au/Pd coating	Tips: No platinum degradation; thin partial tissue encapsulation (~250 nm); no parylene delamination.
			Shafts: Irregular, thin tissue encapsulation (~250 nm) with few cells; several longitudinal parylene cracks; no collagen fibers.
			Base: Many cells at base, few cracks in parylene.
			Edges: No silicone delamination, rare cracks, few tissue adhesions on silicone.
GAR-RMI	554 days	NaCacodylate fix, ethanol, critical point dryer, Au/Pd coating	Tips: No platinum degradation; complete tissue encapsulation (~250–500 nm); rare parylene delamination.
			Shafts: Irregular, thick tissue adhesions (~1–5 μm) with many fibroblasts; many cracks in parylene, often with tissue invasion; many collagen fibers, often connecting adjacent electrodes (central>peripheral).
			Base: Few cells, thin fibrous layer (~250 nm); few cracks in parylene, most shallow.
			Edges: Rare silicone delamination, no cracks; few tissue adhesions found on silicone.
GAR-RPMV	554 days	NaCacodylate fix, ethanol, critical point dryer, Au/Pd coating	Tips: Few cracked platinum tips; complete tissue encapsulation (~250–500 nm); some parylene delamination.
			Shafts: Irregular, thick tissue adhesions (~1–5 μm) with many fibroblasts; many transverse cracks in parylene, often with tissue invasion; many collagen fibers, often connecting adjacent electrodes.
			Base: Few cells; thin fibrous layer (~250 nm) many shallow cracks in parylene, some deep.
			Edges: Minor silicone delamination, no cracks; few tissue adhesions on silicone.
LA-LMI4	639 days	NaCacodylate fix, ethanol, critical point dryer, Au/Pd coating	Tips: No platinum degradation; complete tissue encapsulation (250–500 nm); abundant parylene delamination.
			Shafts: Irregular, thick tissue encapsulation (>500 nm) with many fibroblasts; many cracks in parylene with tissue invasion; many collagen fibers between adjacent electrodes (central>peripheral); parylene often peeled off by tissue.
			Base: Few cells, thick fibrous layer (~500 nm–1 μm); many deep cracks in parylene.
			Edges: Abundant silicone delamination and cracks; numerous tissue adhesions on silicone.
RUS-LPMV2	994 days	NaCacodylate fix, ethanol, critical point dryer, no sputter-coating	Tips: Widespread platinum degradation (>50% of electrodes) with many cracks, often with separation of platinum from silicon and erosion of underlying silicon; thick complete tissue encapsulation (~500 nm) with growth between platinum and silicon; minimal parylene delamination.
			Shafts: Regular, thick tissue encapsulation (>500 nm) with few cells; few parylene cracks; many collagen fibers throughout array, often connecting adjacent electrodes.
			Base: Many cells, thick fibrous layer (500 nm–1 μm); few cracks in parylene.
			Edges: No cracks, 1 mm of silicone delamination at junction of wire bundle; many tissue adhesions on silicone.
RUS-LPFV2	994 days	NaCacodylate fix, ethanol, critical point dryer, no sputter-coating	Tips: Extensive platinum degradation (>66% of electrodes) with many cracks and erosion of underlying silicon; thick complete tissue encapsulation (>500 nm) with growth between platinum and silicon; some parylene delamination.
			Shafts: Regular, thick tissue encapsulation (>500 nm) with few cells; rare parylene cracks; rare collagen fibers.
			Base: Many cells, thick fibrous layer (500 nm–1 μm); few cracks in parylene.
			Edges: Few segments of silicone delamination, few cracks; many tissue adhesions on silicone.
LA-LPE3	1051 days	NaCacodylate fix, ethanol, critical point dryer, Au/Pd coating	Tips: Extensive platinum degradation (>95% of electrodes) with many cracks and erosion of underlying silicon; thick complete tissue encapsulation (>500 nm) with growth between platinum and silicon; some parylene delamination.
			Shafts: Regular, thick tissue encapsulation (500 nm–1 μm) with few cells; few cracks in; no collagen fibers.
			Base: Many cells that merge into thick fibrous layer (1–5 μm) as they ascend shafts; few cracks in parylene.
			Edges: Minimal silicone delamination, few cracks; many tissue adhesions on silicone.