Snowflake-inspired and blink-driven flexible piezoelectric contact lenses for effective corneal injury repair

The cornea is a tissue susceptible to various injuries and traumas with a complicated cascade repair process, in which conserving its integrity and clarity is critical to restoring visual function. Enhancing the endogenous electric field is recognized as an effective method of accelerating corneal injury repair. However, current equipment limitations and implementation complexities hinder its widespread adoption. Here, we propose a snowflake-inspired, blink-driven flexible piezoelectric contact lens that can convert mechanical blink motions into a unidirectional pulsed electric field for direct application to moderate corneal injury repair. The device is validated on mouse and rabbit models with different relative corneal alkali burn ratios to modulate the microenvironment, alleviate stromal fibrosis, promote orderly epithelial arrangement and differentiation, and restore corneal clarity. Within an 8-day intervention, the corneal clarity of mice and rabbits improves by more than 50%, and the repair rate of mouse and rabbit corneas increases by over 52%. Mechanistically, the device intervention is advantageous in blocking growth factors’ signaling pathways specifically involved in stromal fibrosis whilst preserving and harnessing the signaling pathways required for indispensable epithelial metabolism. This work put forward an efficient and orderly corneal therapeutic technology utilizing artificial endogenous-strengthened signals generated by spontaneous body activities.


Statistics
For all statistical analyses, confirm that the following items are present in in the figure legend, table legend, main text, or or Methods section.
n/a Confirmed The exact sample size (n) for each experimental group/condition, given as as a discrete number and unit of of measurement A statement on on whether measurements were taken from distinct samples or or whether the same sample was measured repeatedly The statistical test(s) used AND whether they are one-or or two-sided Only common tests should be described solely by name; describe more complex techniques in the Methods section.
A description of of all covariates tested A description of of any assumptions or or corrections, such as as tests of of normality and adjustment for multiple comparisons A full description of of the statistical parameters including central tendency (e.g. means) or or other basic estimates (e.g. regression coefficient) AND variation (e.g. standard deviation) or or associated estimates of of uncertainty (e.g. confidence intervals) For null hypothesis testing, the test statistic (e.g. F, t, r) with confidence intervals, effect sizes, degrees of of freedom and P value noted Give P values as exact values whenever suitable.
For Bayesian analysis, information on on the choice of of priors and Markov chain Monte Carlo settings For hierarchical and complex designs, identification of of the appropriate level for tests and full reporting of of outcomes Estimates of of effect sizes (e.g. Cohen's d, Pearson's r), ), indicating how they were calculated Our web collection on statistics for biologists contains articles on many of the points above.

Software and code
Policy information about availability of of computer code Data collection

Data analysis
For manuscripts utilizing custom algorithms or or software that are central to to the research but not yet described in in published literature, software must be be made available to to editors and reviewers. We We strongly encourage code deposition in in a community repository (e.g. GitHub). See the Nature Portfolio guidelines for submitting code & software for further information.

Data
Policy information about availability of of data All manuscripts must include a data availability statement This statement should provide the following information, where applicable: -Accession codes, unique identifiers, or or web links for publicly available datasets -A description of of any restrictions on on data availability -For clinical datasets or or third party data, please ensure that the statement adheres to to our policy Yuan Lin Jun 3, 3, 2023 The electrical performance of of all devices was measured by by a Keithley 6514 electrometer and a portable DSO-X2012A oscilloscope. No No commercial, open-source, nor custom code was used for data collection.
The authors declare that all data supporting the findings of of this study are available within the Article and its Supplementary Information. Source data are provided with this paper.

nature portfolio | reporting summary
March 2021

Human research participants
Policy information about studies involving human research participants and Sex and Gender in Research.

Reporting on sex and gender
Population characteristics

Recruitment
Ethics oversight Note that full information on the approval of the study protocol must also be provided in the manuscript.

Field-specific reporting
Please select the one below that is the best fit for your research. If you are not sure, read the appropriate sections before making your selection.

Life sciences Behavioural & social sciences Ecological, evolutionary & environmental sciences
For a reference copy of the document with all sections, see nature.com/documents/nr-reporting-summary-flat.pdf

Life sciences study design
All studies must disclose on these points even when the disclosure is negative.

Sample size
Data exclusions

Replication
Randomization Three healthy subjects participated in voltage monitoring, including two men (Participant I: 23 years old; Participant II: 26 years old) and one woman (24 years old).
The voltage output in the human-worn state was monitored for proof-of-principle testing, and the non-invasive test did not involve tissue damage or biological characterization.
All volunteers participating in the study are entirely voluntary. The voltage output in the human-worn state was monitored for proof-of-principle testing, and the non-invasive test did not involve tissue damage or biological characterization. All volunteers are recruited within the school, stating the duration (30 minutes) and compensation amount ($50). This recruitment excludes individuals with low tolerance to wearing contact lenses. During the participation in the experiment, a principle verification test was conducted to monitor the voltage output of daily blinking while the volunteers were wearing it. Subjects have read the relevant research materials and received satisfactory answers to all questions. Subjects fully understand the relevant medical research materials and the potential risks and benefits of the research. The subjects know that participating in the study is voluntary and have the right to withdraw at any time. The subjects agree to the review of research materials by the drug regulatory department, ethics committee, or applicant and have expressed their willingness to participate in the study. All collected data and information are for research purposes only. The subjects agree to publish research results (including age, sex, and Supplementary Movie 3) in scientific journals or present at scientific conferences.
All experiments performed with animal and human participants were conducted under a standard protocol (1061420210617007)  Our current sample size (n=10) is sufficient, exceeding most experiments related to corneal injury repair. Mice in the intervention (MI) group were intervened with an EF generated by the BPCL. Mice in the sham (MS) group were stimulated with deactivated devices in which the electrodes were disconnected from the BPCL. The mice in the blank (MB) control group had no wearable electrodes. Normal mice without cornea injury were labeled as MNn (n = 10, Male: n= 1-5, Female: n= 6-10). Mice in MI, MS, and MB groups were subjected to the same corneal injury surgery procedure, and the mice were labeled as MIn, MSn, and MBn (n = 10, Male: n= 1-5, Female: n= 6-10). Identical to the grouping of mice, the rabbits were divided into four groups (RN, RI, RS, and RB) and labeled as RNn, RIn, RSn, and RBn (n = 10, Male: n= 1-5, Female: n= 6-10). Both male and female animals were considered and employed to increase statistical robustness.
No data was excluded.
The sample size of experimental animals (mice and rabbits) was 10 to ensure replicability and statistical robustness. From the measured results, the data showed high similarity within the same testing group, and the replicability was good in each group. Attempts at replication were successful. For representative experiments (Figs. 1c,h;3b,h;4f;Supplementary Figures 2d;5b;11c,d;19c;22a,b,c;23a,b), each experiment was repeated independently many times (#3) with similar results, demonstrating good data reproducibility.
Mice and rabbits were randomly allocated into experimental groups. For mice and rabbits, males were labeled as 1-20, and females were

March 2021
Blinding Reporting for specific materials, systems and methods We require information from authors about some types of materials, experimental systems and methods used in many studies. Here, indicate whether each material, system or method listed is relevant to your study. If you are not sure if a list item applies to your research, read the appropriate section before selecting a response. labeled as 21-40. Then, we randomly divided animals numbered 1-20 into four groups and 21-40 into four groups. Then randomly combine the grouped males and females. Mice in the sham (MS) group were stimulated with deactivated devices in which the electrodes were disconnected from the BPCL. The mice in the blank (MB) control group had no wearable electrodes. Normal mice without cornea injury were labeled as MNn (n = 10, Male: n= 1-5, Female: n= 6-10). Mice in MI, MS, and MB groups were subjected to the same corneal injury surgery procedure, and the mice were labeled as MIn, MSn, and MBn (n = 10, Male: n= 1-5, Female: n= 6-10). Identical to the grouping of mice, the rabbits were divided into four groups (RN, RI, RS, and RB) and labeled as RNn, RIn, RSn, and RBn (n = 10, Male: n= 1-5, Female: n= 6-10). Both male and female animals were considered and employed to increase statistical robustness.
N/A. Only one condition that the devices work properly (BPCL intervention group) can affect the results in mouse and rabbit models. There were no significant differences in the other control groups (Sham and Blank). Therefore, the blinding process won't influence the result.
Identity of the cell lines were frequently checked by their morphological features but have not been authenticated by the short tandem repeat profiling.
The cell line was tested for mycoplasma contamination. No mycoplasma contamination was found.
No commonly misidentified cell lines are used in this study.