# Ultra sensitive and flexible MEAs for chronic dopamine detection at both tonic and phasic levels

> **NIH NIH R21** · UNIVERSITY OF PITTSBURGH AT PITTSBURGH · 2020 · $226,370

## Abstract

The ability to quantify spatially discrete dopamine (DA) concentration over a chronic, multi-week timescale is
paramount to unlocking the mechanisms underlying healthy and disease state behavior. DA signaling
throughout the brain occurs over multiple timescales. Phasic signaling results from high frequency burst firing,
whereas tonic DA release is maintained by low frequency “pacemaker firing”. For decades, fast scan cyclic
voltammetry (FSCV) at carbon fiber microelectrodes (CFEs) has been used to record sub second phasic DA
transmission, but measuring resting level, tonic DA concentrations has been a technical challenge. We have
recently shown that conductive polymer nanocomposite coating consisting of poly(3,4-ethylenedioxythiophene)
and acid functionalized carbon nanotubes (PEDOT/CNT) significantly increases electrode sensitivity and
selectivity for DA, and when combined with a novel square wave voltammetry (SWV) protocol, is capable of
measuring resting DA concentrations in vivo with high selectivity. The same coating can also record sub
second DA release using FSCV. Microfabricated multielectrode arrays (MEAs) have been developed to
monitor neurophysiological signals simultaneously from multiple recording sites with high spatial resolution.
However, the poor sensitivity and selectivity of conventional metal electrodes have limited the use of MEAs for
neurochemical sensing. By applying PEDOT/fCNT coating onto MEAs, we can increase both the sensitivity
and selectivity of neurochemical detection from MEA. Furthermore, implantation of stiff MEAs inevitably causes
neuronal damage and inflammatory glial response, both of which compromise sensor performance, especially
for long-term applications. Recent advancement in MEA technology has revealed that flexible and subcellular
sized implants significantly mitigate the foreign body response resulting in seamless integration within neural
tissue. Here, we hypothesize that chronic multisite DA measurement can be enabled through combining the
highly sensitive PEDOT/CNT coating with ultra-small, flexible neural recording probe technology.
The first specific aim is to fabricate PEDOT/fCNT functionalized flexible MEA capable of detecting DA
with sensitivities and LODs in the physiologically relevant concentration range. PEDOT/CNT coating
conditions will be optimized for electrode sites on 16-channel, flexible SU-8 MEAs. DA sensing performance
will be investigated using SWV and FSCV in the presence of interferents. Coating stability will be assessed via
mechanical bending and agar insertion experiments. The second specific aim is to determine the efficacy
of PEDOT/fCNT functionalized flexible MEAs for acute and chronic in vivo DA sensing. In the acute
validation experiments, sensors will be implanted into the DS of anesthetized rats. SWV (measure basal DA)
and FSCV (measure electrically evoked sub second DA) measurements will be recorded from 16 individual
electrode sites spanning the entire sagittal length ...

## Key facts

- **NIH application ID:** 9935035
- **Project number:** 5R21DA049592-02
- **Recipient organization:** UNIVERSITY OF PITTSBURGH AT PITTSBURGH
- **Principal Investigator:** XINYAN Tracy CUI
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $226,370
- **Award type:** 5
- **Project period:** 2019-06-01 → 2022-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9935035

## Citation

> US National Institutes of Health, RePORTER application 9935035, Ultra sensitive and flexible MEAs for chronic dopamine detection at both tonic and phasic levels (5R21DA049592-02). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/9935035. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*