OPTOSTIM - A Wireless, Battery-Powered Optogenetic Headstage

(for freely moving Rodents)

Product Description

In optogenetics, conventional tethered fiber-optic cables physically restrict an animal's natural behavior—particularly in complex behavioral arenas featuring high walls, gates, or environmental obstacles. The Thomas RECORDING OPTOSTIM system eliminates these constraints by providing a completely wireless environment for in-vivo optogenetic stimulation. The system utilizes an ultra-lightweight, microprocessor-controlled stimulator microchip (approx. 1.1 g) that can be subcutaneously implanted. Only the lightweight optical fiber and a rechargeable micro-battery — with a combined weight of just approx. 2.2 g — are mounted onto the animal's skull. This exceptionally low weight and compact form factor make the OPTOSTIM system the ideal choice for both mouse and rat behavioral studies. For maximum experimental flexibility, the OPTOSTIM system adapts to any optogenetic setup, offering user-defined pulse or continuous stimulation patterns with high-frequency capabilities. The implanted stimulator features an integrated magnetic switch for effortless power control (ON/OFF). Additionally, an intuitive computer interface allows researchers to easily program, customize, and update stimulation paradigms.

Features

Thomas RECORDING Wireless, battery-powered optogenetic headstage (OPTOSTIM) uses a constant-dc-current output microstimulator as light source controller and a LED coupled optical fiber with conical tip with attached rechargeable accumulator for precise control of light power for optogenetic stimulation.

Figure 1: Implantable components of the OPTOSTIM System. This picture shows all implantable components of the Thomas RECORDING OPTOSTIM system: (1) programming interface socket, (2) connection cable between stimulator (3) and programming interface socket (1), (3) optical stimulator with integrated constant-current source for constant light emission of the light source, (4) connecetion cable between optical stimulator (3) and connector (6) for accumulator power supply connection, (5) connection cable between optical stimulator (3) and light source connector (7), (8) accumulator power supply connection cable, (9) light source connection cable, (10) 40 mAh accumulator, (11) connector to remove and replace the accumulator, (12) printed circuit board with µLED light source and optical fiber, (13) rat skull

The surgical protocol for the Thomas RECORDING OPTOSTIM system closely follows the standardized subcutaneous implantation pipeline established for wireless rodent microstimulators, as described by Grotemeyer et al. (2024) in npj Parkinson's Disease (DOI: https://doi.org/10.1038/s41531-024-00767-2).

The microstimulator unit features compact dimensions of 15.8 × 10.1 × 4.6 mm and an ultra-lightweight design (1.1 g), allowing it to be comfortably placed into a subcutaneous pocket over the animal's dorsum (spine area). From this back pocket, the connection cables running to the skull-mounted rechargeable micro-battery and the fiber-optic light source are tunneled entirely subcutaneously, minimizing post-operative discomfort and preventing damage from group housing or grooming.

To maintain a minimally invasive profile, only a single, low-profile 4-pin connector port is externalized on the animal's skull. This port is securely anchored using dental restorative cement and serves as the physical interface for the external programming unit to customize stimulation paradigms.

Consistent with the operational design of the wireless deep brain stimulation (wDBS) device validated in the literature, the OPTOSTIM system features an integrated magnetic reed switch. This allows researchers to effortlessly cycle the stimulator between power states (ON/OFF) transcutaneously through the animal's fur using a small external magnet, eliminating the need to handle or stress the animal during ongoing behavioral trials.

Working Principle

Figure 2: Schematic overview of the wireless OPTOSTIM system workflow and hardware configuration.

(A) Programmability and Data Management: The stimulation paradigms are configured via a user-friendly Graphical User Interface (GUI) featuring intuitive pull-down menus for parameter selection. The software facilitates comprehensive experimental tracking by archiving metadata alongside the specific stimulation profiles in an integrated database.

(B) Transcutaneous Programming and Control: The microstimulator is subcutaneously implanted beneath the animal's fur. To update stimulation parameters at any point during the study, the external programming interface is temporarily connected to the skull-mounted 4-pin port. The wireless firmware download of newly defined pulse patterns is completed within seconds. Power states (ON/OFF) are toggled transcutaneously through the fur via an integrated magnetic reed switch, allowing continuous stimulation without handling stress.

(C) Optoelectronic Assembly and Biocompatible Delivery: The implanted microstimulator (6) drives a high-efficiency LED light source (2) coupled to an optical fiber. The fiber features a tapered, conical tip designed to minimize mechanical tissue displacement during stereotaxic insertion, significantly reducing the risk of reactive gliosis.

(D) Power Supply Unit: Electrical power for both the LED source (2) and the stimulator (6) is provided by a head-mounted, rechargeable accumulator (battery) pack (4). This modular battery units are hot-swappable to ensure uninterrupted experimental timelines. The comprehensive system package includes a dedicated battery charging dock.

Optical Fiber Unit

The implantable optical fiber assembly (see figure 3, 0.4 g total mass) consists of a tapered optical fiber (1), a high-power light source (3), an integrated nut (6), a power receptacle for an external battery (4), and flexible connecting leads (7+8).

During stereotactic implantation, a threaded rod (5) is temporarily secured into the nut (6) to interface the assembly with an XYZ micromanipulator for high-precision targeting.

The distal end of the fiber (1) is ground into a conical, pencil-like tip to reduce mechanical trauma upon insertion into neural tissue. The length of the optical fiber is customizable to accommodate varying depths of target brain regions.

The surgical protocol for the implantation closely follows the standardized subcutaneous implantation pipeline established for wireless rodent microstimulators, as described by Grotemeyer et al. (2024) in npj Parkinson's Disease (DOI: https://doi.org/10.1038/s41531-024-00767-2).

Figure 3: The implantable optical fiber unit of the OPTOSTIM system consists of the following components : (1) optical fiber with conical tip shape, (2) ceramic ferrule, (3) light source unit, (4) connector for accumulator, (5) threaded rod for mounting the unit to a stereotaxic xyz-manipulator during implantation, (6) screw attached to the optical fiber unit for threaded rod, (7) power supply cable, (8) cable to stimulator output.

Figure 4: Atraumatic Optical Fiber Tip Geometries: To minimize mechanical damage during stereotactic insertion into neural tissue, the implantable optical fiber unit of the OPTOSTIM system is available with three distinct atraumatic tip geometries, as illustrated in this figure. These tapered profiles are specifically engineered to gently displace rather than sever brain parenchyma, thereby preserving local microvasculature and neural integrity. For applications requiring specific illumination profiles, a standard flat-cleaved (blunt) fiber end is also available upon request. However, blunt tips induce significantly greater mechanical tissue trauma during penetration, which substantially increases the risk of neuroinflammation and reactive gliosis (glial scarring) around the implant site.

Programming Software

Figure 5: Graphical User Interface (GUI) of the OPTOSTIM Programming Software.
The software features a standard pull-down menu at the top and allows researchers to configure customized optogenetic stimulation protocols, including light intensity, pulse width, and pulse frequency. Selected stimulation parameters (4) are rendered in real time within an integrated oscilloscope-style waveform display (6). An embedded step-by-step workflow guide (3) ensures that all mandatory configuration steps are completed sequentially without omission. Furthermore, the interface provides dedicated fields for entering experimental metadata (2), which are automatically archived alongside the corresponding stimulation parameters and a unique Experiment ID in an integrated database for reproducible data management.

Implantable Stimulator

Figure 6. Implantable Microprocessor-Controlled Optogenetic Stimulator. The device is enclosed in a biocompatible housing (1) designed for chronic subcutaneous implantation in freely moving rodents. It integrates a precision constant-current source connected to the high-power light source of the OPTOSTIM optical fiber unit, ensuring stable emission of light pulses with constant optical intensity according to the programmed duty cycle, pulse width, and pulse frequency. Stimulation protocols configured via the graphical user interface (GUI) are uploaded to the onboard microprocessor through a temporary programming interface (3). For wireless, non-invasive operation in implanted animals, the stimulator is toggled on and off using an external magnet, while a white indicator LED visibly shines through the animal's fur to confirm active operation.

Optogenetic stimulation is delivered by a miniature, microprocessor-controlled stimulator (dimensions: 16 × 10 × 5 mm [L × W × H]; weight: 1.1 g) encapsulated in a biocompatible housing for chronic implantation in freely moving rodents (see Figure 6).

The device is equipped with three flexible leads: a power lead (2) connected to the battery mounted on the fiber unit, an output lead (4) driving the high-intensity light source of the OPTOSTIM fiber unit via an onboard constant-current source, and a programming lead (3) fitted with a 4-pin receptacle.

To allow protocol updates in implanted animals, the 4-pin receptacle must be implanted so that it remains accessible from the outside, permitting temporary attachment of a programming device to transfer GUI-configured parameters to the microprocessor. The constant-current source guarantees consistent irradiance across the selected pulse width, pulse frequency, and duty cycle. In vivo, the stimulator is switched on or off non-invasively using an external magnet, and active operation is confirmed by a bright white indicator LED visible through the rodent's fur.

Structured Comparison Table

Below you can find a well-researched analysis of the key unique selling points (USPs) of our OPTOSTIM system, directly addressing the specific technical limitations identified in the review article by Silva & Jacinto (2025, see [1] below).

1. Minimal Tissue Trauma & Reduced Gliosis via Atraumatic Conical Fiber Tips

Advantage over competitors. Conventional fiber-coupled wireless systems reviewed by Silva & Jacinto rely on standard flat-cleaved (blunt) optical fibers (typically 200–500 µm diameter), while implantable µLED probes often have bulky rectangular cross-sections (up to 300–700 µm wide) that sever brain parenchyma during insertion.
TREC OPTOSTIM USP. OPTOSTIM features precision-ground, conical (pencil-shaped) and atraumatic fiber tip geometries that gently displace rather than shear neural tissue. This preserves local microvasculature and minimizes acute trauma as well as chronic reactive gliosis (glial scarring), preventing light attenuation over long-term studies.

2. Zero Intracerebral Thermal Load (Eliminating µLED Tissue Heating)

Advantage over competitors. Silva & Jacinto emphasize that implantable µLED probes dissipate electrical heat directly inside the brain via resistive tracks and LED junctions. Temperature increases exceeding 1 °C can induce non-specific thermal artifacts in neuronal firing or cause tissue damage, strictly limiting maximum irradiance and duty cycles in µLED devices.
TREC OPTOSTIM USP. By keeping the high-power light source extracerebral and guiding light to the target region via a low-loss optical fiber, OPTOSTIM completely decouples heat dissipation from the neural tissue. Researchers can apply high irradiance levels and extended duty cycles without risking thermally induced behavioral or physiological artifacts.

3. Ultra-Lightweight Implantable Architecture with Swappable Extracorporeal Battery

Advantage over competitors. As highlighted in the review, onboard batteries account for a major portion of the weight and bulk in head-mounted devices (often reaching 1.6 g to 3.2 g, which exceeds optimal comfort limits for mice), whereas battery-free wireless power transfer (WPT) systems restrict experiments to small, specialized resonant arenas (< 0.3–1 m range) and suffer from angular coupling drops.
TREC OPTOSTIM USP. With an ultra-low implantable mass (0.4 g for the optical fiber unit, 1,1 g for the accumulator and 1.1 g [16 × 10 × 5 mm] for the subdermal stimulator), the active electronics and light source are fully implantable, while the power source remains extracorporeal and easily replaceable. This eliminates arena size restrictions, avoids RF/WPT dead zones or angle dependencies, and allows rapid battery swaps without surgical intervention or prolonged downtime.

4. Commercial Availability vs. Academic Prototypes

Advantage over competitors. The vast majority of systems cataloged by Silva & Jacinto are academic proof-of-concept prototypes fabricated in university cleanrooms (with several previously commercialized systems, such as TBSI, no longer operational).
TREC OPTOSTIM USP. OPTOSTIM is a commercially available, turnkey system ready for immediate deployment in neuroscience laboratories, eliminating the need for in-house microfabrication, PCB assembly, or custom firmware debugging.

5. Industrial QM-Certified Manufacturing for High Experimental Reproducibility

Advantage over competitors. Hand-soldered or lab-assembled prototypes often suffer from batch-to-batch variability in optical coupling efficiency, irradiance output, and encapsulation integrity.
TREC OPTOSTIM USP. Every OPTOSTIM component is manufactured under standardized industrial processes backed by strict Quality Management (QM) testing. Combined with an onboard constant-current driver and automated GUI database logging (storing metadata, stimulation parameters, and unique Experiment IDs), this guarantees consistent irradiance across animals and cohorts, maximizing data reproducibility.

6. Customizability & User-Friendly Workflow Without Arena or Lighting Interference

Advantage over competitors. Many reviewed devices require terminal commands, lack intuitive software, or rely on infrared (IR) communication that suffers from short range (< 1.8 m) and interference from standard animal facility fluorescent lighting.
TREC OPTOSTIM USP. OPTOSTIM provides custom-tailored fiber lengths and tip geometries matched to the exact stereotactic depth of any target brain region. Stimulation protocols are configured effortlessly via a step-by-step Windows GUI with real-time oscilloscope preview, uploaded via a percutaneous 4-pin interface, and toggled non-invasively in any behavioral arena using a simple external magnet—completely immune to ambient lighting or RF shielding.

Literature:

[1] P. Silva and L. Jacinto,

Wireless Devices for Optical Brain Stimulation: A Review of Current Developments for Optogenetic Applications in Freely Moving Mice,

(in eng), Cell Mol Bioeng, vol. 18, no. 1, pp. 1–13, Feb 2025, doi: 10.1007/s12195-024-00832-z.

OPTOSTIM vs. State-of-the-Art Wireless Optogenetic Systems

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