A Single-Chip Solar Energy Harvesting IC Using Integrated Photodiodes for Biomedical Implant Applications

Abstract

In this paper, an ultra-compact single-chip solar energy harvesting IC using on-chip solar cell for biomedical implant applications is presented. By employing an on-chip charge pump with parallel connected photodiodes, a 3.5 × efficiency improvement can be achieved when compared with the conventional stacked photodiode approach to boost the harvested voltage while preserving a single-chip solution. A photodiode-assisted dual startup circuit (PDSC) is also proposed to improve the area efficiency and increase the startup speed by 77%. By employing an auxiliary charge pump (AQP) using zero threshold voltage (ZVT) devices in parallel with the main charge pump, a low startup voltage of 0.25 V is obtained while minimizing the reversion loss. A 4 V gate drive voltage is utilized to reduce the conduction loss. Systematic charge pump and solar cell area optimization is also introduced to improve the energy harvesting efficiency. The proposed system is implemented in a standard 0.18- [Formula: see text] CMOS technology and occupies an active area of 1.54 [Formula: see text]. Measurement results show that the on-chip charge pump can achieve a maximum efficiency of 67%. With an incident power of 1.22 [Formula: see text] from a halogen light source, the proposed energy harvesting IC can deliver an output power of 1.65 [Formula: see text] at 64% charge pump efficiency. The chip prototype is also verified using in-vitro experiment.

Micro-Energy Harvesting System Including a PMU and a Solar Cell on the Same Substrate With Cold Startup From 2.38 nW and Input Power Range up to 10 $\mu$W Using Continuous MPPT

“…1 depicts, the classical approach of light energy harvesting consists of an off-chip solar cell stuck over a CMOS chip with a Power Management Unit (PMU) [1]. Nevertheless, by integrating the solar cell and the CMOS circuitry on the same silicon substrate, a very small form factor and reduced cost can be met [7]. This approach, however, leads to several design challenges of the PMU.…”

Energy Harvesting: A Toxic Free and Reliable Power Source for Implantable Microsystems

“…Various harvesters are being proposed to harvest energy for implantable devices. Some of the recently reported harvesters can be studied in [15][16][17][18][19][20][21]. The form of energy used by the harvester to scavenge the power, defines the type of energy harvesting.…”

Modelling of Implantable Photovoltaic Cells Based on Human Skin Types

“…In this case, a surgical battery replacement is required to prolong the usage of implantable device. To overcome this problem, there are lots of powering technologies such as the piezoelectric generator, wireless power transfer coils, thermal-electric generator, biofuel generator and implantable solar power harvester [3][4][5]. Compared with the other powering topologies, the implantable photovoltaic cell (PV) takes advantages of no external powering unit, sustainable and reliable power output and high output voltage.…”