An inductively-powered wireless integrated neural recording and stimulation (WINeRS-8) system-on-a-chip (SoC) that is compatible with the EnerCage-HC2 for wireless/battery- less operation has been presented for neuroscience experiments on freely behaving animals. WINeRS-8 includes a 32-ch recording analog front-end (AFE), a 4-ch current-controlled stimulator, and a 434 MHz on-off keying (OOK) data link to an external software- defined radio (SDR) wideband receiver (Rx). The headstage also has of a Bluetooth Low Energy (BLE) link for controlling the SoC. WINeRS-8/EnerCage-HC2 systems form a bidirectional wireless and battery-less neural interface within a standard homecage, which can support longitudinal experiments in an enriched environment. Both systems were verified in vivo on rat animal model, and the recorded signals were compared with hardwired and battery-powered recording results. Real-time stimulation and recording verified the system's potential for bidirectional neural interfacing within the homecage, while continuously delivering 35 mW to the hybrid WINeRS-8 headstage over an unlimited period.

This paper presents a mm-sized, free-floating, wirelessly powered, implantable optical stimulation (FF-WIOS) device for untethered optogenetic neuromodulation. A resonator-based three-coil inductive link creates a homogeneous magnetic field that continuously delivers sufficient power (>2.7 mW) at an optimal carrier frequency of 60 MHz to the FF-WIOS in the near field without surpassing the specific absorption rate limit, regardless of the position of the FF-WIOS in a large brain area. Forward data telemetry carries stimulation parameters by on-off-keying the power carrier at a data rate of 50 kb/s to selectively activate a 4 × 4 μLED array. Load-shift-keying back telemetry controls the wireless power transmission by reporting the FF-WIOS received power level in a closed-loop power control mechanism. LEDs typically require high instantaneous power to emit sufficient light for optical stimulation. Thus, a switched-capacitor-based stimulation architecture is used as an energy storage buffer with one off-chip capacitor to receive charge directly from the inductive link and deliver it to the selected μLED at the onset of stimulation. The FF-WIOS system-on-a-chip prototype, fabricated in a 0.35-μm standard CMOS process, charges a 10-μF capacitor up to 5 V with 37% efficiency and passes instantaneous current spikes up to 10 mA in the selected μLED, creating a bright exponentially decaying flash with minimal wasted power. An in vivo experiment was conducted to verify the efficacy of the FF-WIOS by observing light-evoked local field potentials and immunostained tissue response from the primary visual cortex (V1) of two anesthetized rats.

Wireless power and bidirectional wireless data transfer system using a conventional 2-coil inductive link is presented for Internet-of-Things (IoT) and mobile applications without any additional coil or antenna. The proposed system utilizes the dual-band frequency shift-keying and the load shift-keying for the downlink and uplink telemetries, respectively, while ∼140 mW power is delivered to the receiver in the 2-coil inductive link. The data rates for downlink and uplink telemetries are 800 kb/s and 14 kb/s with 3.12 × 10 ⁻⁵ and <10 ⁻⁶ bit error rate at 10 mm distance, respectively.

This paper presents a reconfigurable bidirectional wireless power and data transceiver (RB-WPDT) integrated circuit (IC) for wearable biomedical applications. The proposed transceiver can be reconfigured as a differential class-D power amplifier or a full-wave rectifier depending on the mode signal to facilitate power transfer between devices. Additionally, the RBWPDT system supports full-duplex (FD) data transmission via a single inductive link, enabling real-time control and monitoring between devices. The proposed FD method utilizes frequency shift-keying pulse-width modulation (FSK-PWM) for downlink and load shift-keying (LSK) for uplink, achieving simultaneous bidirectional data transmission by ensuring that the FSK-PWM downlink and LSK uplink data channels operate independently with minimal interference. The measured downlink and uplink data rates are 250 kb/s and 67 kb/s, respectively. The measured overall DC-to-DC efficiency is 49%, while the power delivered to the load (PDL) is 120 mW at a 5 mm distance. The proposed chip is fabricated using a 180-nm BCD CMOS process.