Understanding how cortical circuits respond to pharmacological regulation requires simultaneous observation of multilevel neural signals, including neuronal spikes, local field potentials, and neurotransmitter dynamics. Electrophysiological recording provides high-temporal-resolution information about spikes and LFPs, while electrochemical detection can track dynamic fluctuations in neurotransmitters such as dopamine. Combining these modalities can offer a more complete view of brain state transitions. However, most existing methods focus on only one signal type or rely on tethered recording systems, which restrict animal movement and may introduce mechanical artifacts. Current wireless systems also mainly support electrophysiological recording and rarely achieve stable simultaneous acquisition of electrophysiological and neurochemical signals. "Dexmedetomidine, a widely used sedative and analgesic drug, still shows debated effects on cortical activity and dopamine signaling, with inconsistent findings across different measurement techniques." said the author Peiyao Jiao, a researcher at Aerospace Information Research Institute, Chinese Academy of Sciences, "Therefore, developing an in vivo wireless microsystem capable of simultaneously monitoring electrophysiological signals and dopamine-related electrochemical signals is important for studying drug-induced neural circuit regulation and neurotransmitter dynamics."
This study developed a dual-mode wireless microsystem capable of simultaneously monitoring electrophysiological signals and dopamine-related electrochemical signals. The researchers first constructed a dual-mode microelectrode array, in which electrophysiological sites were modified with PtNPs/PEDOT to record spikes and local field potentials, while the electrochemical sensing site was further modified with rGO and Nafion to form a PtNPs/PEDOT/rGO/Nafion structure for more sensitive and selective dopamine detection. At the hardware level, the platform integrated an electrophysiological acquisition chip and an AD5941 electrochemical front end, using an FPGA–ESP32 dual-controller architecture to support independent acquisition and wireless transmission of the 2 signal types. Electrophysiological and electrochemical data were transmitted through separate TCP ports to reduce interference between modalities. The team then evaluated dopamine calibration, selectivity, wireless transmission accuracy, transmission distance, and timing alignment in vitro. Finally, the system was implanted into the rat prelimbic cortex, where spikes, local field potentials, and dopamine-related amperometric responses were simultaneously recorded under saline and different doses of dexmedetomidine, allowing the researchers to analyze dose-dependent effects on cortical neural activity and neurochemical signals.
The results showed that the dual-mode wireless microsystem could stably achieve dopamine-related electrochemical detection and simultaneous electrophysiological recording. In vitro tests demonstrated that the PtNPs/PEDOT/rGO/Nafion-modified electrode produced a stronger oxidation response to dopamine, with a low detection limit, good linearity, and strong selectivity, effectively distinguishing dopamine from interferents such as uric acid, serotonin, ascorbic acid, and lactic acid. Wireless detection further showed that the system maintained a stable linear current response to dopamine concentration, while achieving high transmission accuracy over 0 to 25 m and millisecond-level alignment between electrophysiological and electrochemical data streams, indicating that the platform can meet the requirements of in vivo dual-mode recording. In rat prelimbic cortex experiments, saline induced only minimal changes in neural activity and dopamine-related responses, whereas dexmedetomidine produced clear dose-dependent effects. As the dose increased, spike firing rate and peak-to-peak amplitude gradually decreased, overall local field potential power was suppressed, delta-band power increased, and gamma-band power decreased, suggesting a shift of cortical network activity toward a lower-arousal state. At the same time, the dopamine-related amperometric response increased with dose. Together, these results show that the system can simultaneously capture drug-induced electrophysiological suppression and neurochemical changes within the same brain region, providing a practical tool for studying neural circuit state transitions under anesthetic or sedative modulation.
The significance of this work lies in building a dual-mode wireless microsystem capable of simultaneously recording in vivo electrophysiological activity and dopamine-related electrochemical signals, providing a more complete technical tool for studying the relationship between neural circuit activity and neurotransmitter dynamics under pharmacological regulation. Compared with conventional single-modality or tethered recording systems, this platform preserves 32-channel high-sampling-rate electrophysiological recording while adding a dopamine electrochemical sensing pathway and a dual-TCP wireless transmission architecture, enabling synchronized acquisition, visualization, and storage of spikes, local field potentials, and neurochemical signals. Using this system, the study observed that dexmedetomidine dose-dependently reduced neuronal firing and high-frequency LFP activity in the prelimbic cortex, while increasing the dopamine-related amperometric response, indicating that the platform can capture the parallel evolution of neural electrical activity and neurochemical changes during sedation. At the same time, several limitations remain. The sample size was small, and in vivo constant-potential amperometric signals may be affected by electrode fouling, baseline drift, local pH, oxygen concentration, tissue responses, and reference electrode stability; therefore, the current findings are better interpreted as dopamine-related responses rather than absolute extracellular dopamine concentrations. "In addition, the system still relies on commercial off-the-shelf components, leaving room for further size and weight optimization, and it currently supports recording only without integrated stimulation or closed-loop modulation. Future work could further enhance its value in neurological disease models, neurorehabilitation, and cognitive studies by developing dedicated integrated circuits, multimodal closed-loop systems, multi-region recording strategies, and orthogonal neurochemical validation." said Peiyao Jiao.
Authors of the paper include Peiyao Jiao, Yilin Song, Jin Shan, Yu Liu, Qianli Jia, Qi Li, Ying Wang, Yan Luo, Pengfei Zhao, Juntao Liu, Zhenchang Wang, Mixia Wang, and Xinxia Cai.
This work was sponsored by the National Natural Science Foundation of China (T2293730, T2293731, 62121003, 62333020, 62171434, and 62471291), the Major Program of Scientific and Technical Innovation 2030 (no. 2021ZD0201600), the Joint Foundation Program of the Chinese Academy of Sciences (no. 8091A170201), and the Natural Science Foundation of Beijing (F252069).
The paper, "A Dual-Mode Wireless Microsystem for Monitoring Dopamine and Spike Changes with Dexmedetomidine" was published in the journal Cyborg and Bionic Systems on May 21, 2026, at https://doi.org/10.34133/cbsystems.0566
