A 1225-Channel Neuromorphic Retinal Prosthesis (RP) SoC is presented. Existing RP SoCs directly convert light intensity to electrical stimulus, which limit the adoption of delicate stimulus patterns to increase visual acuity. Moreover, a conventional centralized image processor leads to the local hot spot that poses a risk to the nearby retinal cells. To solve these issues, the proposed SoC adopts a distributed Neuromorphic Image Processor (NMIP) located within each pixel that extracts the outline of the incoming image, which reduces current dispersion and stimulus power compared with light-intensity proportional stimulus pattern. A spike-based asynchronous digital operation results in the power consumption of 56.3 nW/Ch without local temperature hot spot. At every 5×5 pixels, the localized (49-point) temperatureregulation circuit limits the temperature increase of neighboring retinal cells to less than 1°C, and the overall power consumption of the SoC to be less than that of the human eye. The 1225-channel SoC fabricated in 0.18 µm 1P6M CMOS occupies 15mm 2 while consuming 2.7 mW, and is successfully verified with image reconstruction demonstration.
This article presents a fully energy-autonomous temperature-to-time converter (TTC), entirely powered up by a triboelectric nanogenerator (TENG) for biomedical applications. Existing sensing systems either consume too much power to be sustained by energy harvesting or have poor accuracy. Also, the harvesting of low-frequency energy input has been challenging due to high reverse leakage of a rectifier. The proposed dynamic leakage suppression full-bridge rectifier (DLS-FBR) reduces the reverse leakage current by more than 1000×, enabling harvesting from sparse and sporadic energy sources; this enables the TTC to function with a TENG as the sole power source operating at <1-Hz human motion. Upon harvesting 0.6 V in the storage capacitor, the power management unit (PMU) activates the low-power TTC, which performs one-shot conversion of temperature to pulsewidth. Designed for biomedical applications, the TTC enables a temperature measurement range from 15 • C to 45 • C. The energy-autonomous TTC is fabricated in 0.18-µm 1P6M CMOS technology, consuming 0.14 pJ/conversion with 0.014-ms conversion time. Index Terms-Biomedical applications, dynamic leakage suppression full-bridge rectifier (DLS-FBR), energy harvesting, energy autonomous, Internet of Things (IoT), low leakage, low power, temperature-to-time converter (TTC).
I. INTRODUCTIONT EMPERATURE information acquisition is essential in assessing and monitoring the operation conditions of sensor nodes/devices widely employed in assisted diagnostics, remote healthcare, and Internet-of-Things (IoT) nodes in general. With the devices worn or implanted in patients,
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