# Wireless, Self-Powered Sensors for Continuous and Long-term Monitoring of Spinal Fusion Process

> **NIH NIH R21** · UNIVERSITY OF PITTSBURGH AT PITTSBURGH · 2020 · $172,652

## Abstract

PROJECT SUMMARY
Achieving better surgical outcomes and research studies involving lumbar spinal fusion requires reliable
determination and degree of fusion. Current imaging technologies are not suitable to accurately and reliably
determine different degrees of spinal fusion. These modalities are costly and expose the patient to significant
radiation. In addition, nearly all of the previously developed implantable telemetry systems comprise on-board
energy storage devices (batteries and super-capacitors) for sensing, computation, storage, and wireless
communication. The use of batteries in biomedical implants is not suitable due to their limited life time, large
size, and chemical risks. The rest of these spinal implants use radio-frequency identification (RFID) technology
or other inductive methods to interrogate the sensor, which faces severe limitations inside the tissue. Similar to
the imaging techniques, the current spinal implants evaluate the fusion condition at a given instant and present
only a “snapshot at the time” where the measurements are taken.
In this research study, we propose to investigate the feasibility of a wireless, self-powered piezo-floating-gate
(PFG) sensor capable of monitoring the spinal fusion progress by continuously recording the mechanical usage
of the spinal fixation device during the entire time course of fusion. The uniqueness of the proposed sensor is
that the operation is completely self-powered by the micro-motion of the spine without the need for any implanted
batteries or any external powering. Data collected by the sensor will be wirelessly retrieved using a portable
ultrasound-scanner and the resulting output will be time-evolution curves, which will be correlated with the
changes of functional spinal unit (FSU) stiffness. These evolution curves would enable clinicians to differentiate
between conditions of osseous union, assess the effective fusion period, and schedule for more accurate implant
removal in several types of spinal fusion procedures.
Our first objective for this research will be to design a fully integrated spinal fusion implant with self-powered
monitoring and wireless data retrieval capabilities. The research activity will involve designing and prototyping
the ultrasonic energy harvesting and telemetry circuits in silicon and subsequently validating the functionality of
the fabricated modules using a cadaver model. The challenge will be to achieve high energy efficiency of the
telemetry circuit modules given the limited amount of energy that can be delivered by the ultrasound scanner to
a millimeter-scale sensor. Our second objective will be bench-top testing to evaluate the performance of the PFG
sensor and the ultrasonic telemetry interface for the monitoring of simulated posterior lumbar spinal fusion in
human cadaver spines. Prior to testing on cadaver spines, the PFG spinal implants will be tested using a
corpectomy model. Upon successful completion of this study, we will have demons...

## Key facts

- **NIH application ID:** 10001440
- **Project number:** 5R21AR075242-02
- **Recipient organization:** UNIVERSITY OF PITTSBURGH AT PITTSBURGH
- **Principal Investigator:** Amir Alavi
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $172,652
- **Award type:** 5
- **Project period:** 2019-09-01 → 2021-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10001440

## Citation

> US National Institutes of Health, RePORTER application 10001440, Wireless, Self-Powered Sensors for Continuous and Long-term Monitoring of Spinal Fusion Process (5R21AR075242-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10001440. Licensed CC0.

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