Today, tomorrow, learn English naturally. 天天自然学英语
Solar panels in your eyeballs: Self-powered bionics are on the way
Implanting tiny solar panels into people's eyeballs may sound like science fiction, but that's exactly what a team of Australian scientists are working on. The next-gen tech could vastly improve quality of life for people with incurable eye diseases.
Neuroprosthetics interact with the nervous system to restore lost functionality. A good example is the cochlear implant, a small electronic device surgically implanted in the inner ear that stimulates the hearing nerve to provide sound signals directly to the brain, improving hearing.
Now, researchers from the University of New South Wales (UNSW) are exploring whether a similar neuroprosthetic technology can restore vision in people with damaged photoreceptors, specialized cells in the retina capable of absorbing light and converting it into electrical signals that can be sent to the visual cortex.
Camera sensor chips offer high resolution, extreme color depth and an increasing degree of low-light sensitivity – but there's one key issue: they need to be powered. One shudders to think where the battery would go for a camera sensor in your eyeball, or how you'd change or charge it. On the other hand, there's another technology capable of turning light directly into electricity – solar photovoltaic panels.
“People with certain diseases like retinitis pigmentosa and age-related macular degeneration slowly lose their eyesight as photoreceptors at the center of the eye degenerate,” said Udo Römer, an engineer whose expertise is in photovoltaics, commonly known as solar panel tech. “It has long been thought that biomedical implants in the retina could stand in for the damaged photoreceptors. One way to do this is to use electrodes to create [a] voltage pulse that may enable people to see a tiny spot.”
From light comes vision (usually)
When light hits the retina at the back of the eye, photoreceptors convert it into electrical signals. These signals travel from the retina through the optic nerve to the brain, where they’re turned into the images you see.
Retinitis pigmentosa (RP) is the name given to a group of rare genetic eye diseases that cause the slow breakdown of the image-capturing photoreceptors, leading to vision loss over time. In age-related macular degeneration (AMD), the macula, the part of the retina that controls sharp, straight-ahead vision, is damaged, leading to vision loss in the central field of vision. Currently, there’s no cure for RP or AMD.
Chance meeting: a melding of photovoltaics and biomedicine
Römer’s reason for embarking on this research was a chance meeting with a biomedicine student.
“I was helping a PhD student from our biomedical school out with processing, and we had some interesting discussions about all the different research that is going on in their group,” Römer told New Atlas. “I [very] much enjoy working on solar cells, but a lot of what they do is super interesting and sounds quite futuristic. His PhD project was in solar cells for neural stimulation, and he showed me a research paper from the Palanker Group at Stanford that was about retinal implants using silicon solar cells – probably one of the most fascinating papers I have read because it sounds like science fiction.”
Initially, Römer was put off by the already advanced research into using photovoltaic cells to restore sight, so he put the idea to one side.
“But it was something that lingered in my head because of how awesome it was,” Römer explains. “A few months later, when I was discussing a research project with my supervisor, we were talking about multijunction solar cells, which are basically a couple of different solar cells stacked on top of each other to better use the full solar spectrum. At this point, it clicked, and I thought, ‘Maybe stacking solar cells could solve one of the complications with the device that the Palanker Group is working on.’”
Stacking solar cells and a change of material
As Römer saw it, the Palanker Group's problems could be overcome by stacking solar cells and changing the semiconductor material used in the device.
“They needed to interconnect three tiny Si [silicon] solar cells in each of the pixels to increase the voltage to a value that is high enough for reliably stimulating neurons,” the engineer told New Atlas. “In order to stimulate neurons, you need a higher voltage than what you get from one solar cell. If you imagine photoreceptors as pixels, then we really need three solar cells to create enough voltage to send to the brain. Stacking solar cells would do exactly the same [as interconnecting them] but would potentially allow smaller pixels and, thereby, higher resolution. While we cannot easily stack Si solar cells, this is somewhat routinely done with materials like gallium arsenide.”
Silicon remains the most common semiconductor used in the solar cell industry. Other materials like gallium arsenide (GaAs) and gallium indium phosphide (GaInP) are also used. While these materials are not as cheap as silicon, their advantage is that their properties are easier to tune.
After “quite a bit of research and some calculations,” Römer submitted a Discovery Early Career Researcher Award (DECRA) application to the Australian Research Council and secured funding for the project. Then, it was full steam ahead to improve the technology.
“There have already been trials with this technology,” Römer said. “But the problem with this is they require wires going into the eye, which is a complicated procedure.”
An alternative idea is to use a tiny solar panel attached to the eyeball. This panel would naturally be self-powered and portable, avoiding the need for wires into the eye.
Proof-of-concept with huge potential
The technology is currently at the proof-of-concept stage. The next step is to transform the tiny solar cells into the tiny pixels needed for accurate sight.
“So far, we’ve successfully put two solar cells on top of each other in the lab on a large area – about 1 cm2 – which has got some good results,” Römer said. He anticipates that after extensive lab testing and testing in animal models, the device will be about 2 mm2 with pixels measuring around 50 micrometers. By then, it should be ready to test in humans, but that is some time away.
Römer notes that the device only works when laser light is shone on it, and that patients would only see in fairly low-resolution black-and-white.
“One thing to note is that even with the efficiencies of stacked solar cells, sunlight alone may not be strong enough to work with these solar cells implanted in the retina,” said Römer. “People may have to wear some sort of goggles or smart glasses that work in tandem with the solar cells that are able to amplify the sun signal into the required intensity needed to reliably stimulate neurons in the eye.”
He also assures us that the device couldn’t be used for nefarious purposes.
“This is really ‘only’ a medical device that can help patients with certain diseases retain some vision,” Römer told New Atlas. “We are far from a cyborg application.”
注释：
Neuroprosthetic: n
表示"神经假体"，如：neuroprosthetic device 神经假体
cochlear： adj; n
表示" 耳蜗的; 耳蜗"，means "of or relating to the cochlea of the ear"，如：Cochlea is spiral-shaped part of the inner ear. 耳蜗是内耳里螺旋状的部分。
photoreceptor: n
表示" 光感受器；感光器"，如：The photoreceptor cells transform the light into nerve impulses. 视觉感受器将光线转换为神经脉冲。
retina: n
表示" 视网膜"，means "the innermost light-sensitive membrane covering the back wall of the eyeball;"，如：Sight is made possible by rays of light impinging on the retina. 由于光线射到视网膜上,眼睛才看得见。
cortex: n
表示" 外皮；（大脑）皮层"，means "the layer of unmyelinated neurons (the grey matter) forming the cortex of the cerebrum"，如：The inner layer of the cortex differentiates into the endodermis. 皮层的内层分化为内皮层。
shudder: v
表示" 战栗；发抖"，means " shiver or tremble"，如：She shuddered at the sight of the dead body. 她一看到死尸就战栗起来。
photovoltaic: adj
表示"光生伏打的"，means "producing a voltage when exposed to radiant energy (especially light)"，如：copper oxide photovoltaic cell 氧化铜光生伏打电池.
retinitis pigmentosa： n
表示"色素性视网膜炎"，如：Retinitis pigmentosa, or R.P, is a form of retinal degeneration. 视网膜炎或R.;P是视网膜变性的一种。
macular: adj
表示"有斑点的；有污点的"，如： macular degeneration 黄斑部变性
futuristic: adj
表示"未来的；未来派(艺术)的；未来主义的"，means "of or relating to futurism"，如：Her novel depicts a futuristic America. 她的小说描述了未来美国
multijunction: n
表示"多结"，如：multijunction photocell 多结光电池
gallium arsenide: n
表示"砷化镓"，如：To produce the electron beam, a laser will fire at a target made of gallium arsenide, knocking off billions of electrons with each pulse. 产生电子射束的方法，是利用一道雷射轰击用砷化镓制成的标靶，每个脉冲会打出几十亿个电子。
indium phosphide: n
表示"磷化铟"，如：Abstract Indium phosphide clusters were formed in the preparation of nanocrystalline InP through a nonaqueous thermal process. 在非水体系加压热处理制备纳米磷化铟中观察到了磷化铟团簇，该团簇在UV－Vis光谱285nm处出现吸收。
tandem: n
表示" 串联"，means "an arrangement of two or more objects or persons one behind another"，如：I've never ridden a tandem bicycle before. 我从来没骑过双人自行车。
nefarious: adj
表示"违法的；邪恶的"，means "extremely wicked"，如：He guarded his nefarious doings from view. 他不让自己的罪恶行径给人看到。
cyborg: n
表示" 半机械人"，means "a human being whose body has been taken over in whole or in part by electromechanical devices"，如：Denise: You look like some kind of 11)cyborg! 丹尼斯：你看起来像某种生化机械人！
中文简要说明：
与传统假肢只有外观不同，「仿生学科技」(Biomimicry)是利用电子技术实现类似实际功能的替代器官。目前听力的部分已实现「人工耳蜗」，这是一种透过手术植入内耳的小型电子设备，可以刺激听觉神经，直接向大脑提供声音讯号，从而改善听力。 那么，眼睛也可以吗? 科学家相信，真正有功能的生化电子义眼可能不在久后就问世。
我们的眼睛就像照相机，其中担任「底片」的部分，是眼睛底部的视网膜，当光线照射到眼睛后部的视网膜时，视网膜上的感光细胞将其转换为电子讯号。这些讯号通过视神经传输到大脑，并在大脑中转化为我们看到的视力。
然而，不知为何，我们的眼睛具有先天上的缺陷，视网膜与感光细胞容易失去作用，包括视网膜剥离、黄斑部病变，青光眼等等，都因各种原因使感光细胞凋零，最终无法视物。
科学家思考，是否可以在眼睛底部植入人工感光器来取代受损的感光细胞，感光器产生的电压脉冲刺激视神经，使人们能够看到微小的点。这就是人工视网膜的想法。利用愈来愈高级的感光组件芯片(CCD)做为生化电子眼的基础，它提供高分辨率的电讯号。但这有一个关键问题：它们需要供电。
新南韦尔斯大学(UNSW)有了新的研究方向，利用微型太阳能光电板来为生化电子眼供电。
主要研究员罗默(Udo Römer)表示，他开始这项研究的原因，是一次与生物医学学生的交流，他说：「我的专业是太阳能光电板，有一回，我与我们学校的生物医学院博士生进行跨科系交流，他告诉我他的博士计划是利用太阳能光电创造人工神经讯号，他向我说明史丹佛大学帕兰克教授(Daniel Palanke)的研究论文，关于使用硅太阳能光电植入视网膜的可能，这是我读过的最科幻的论文之一，它根本就像科幻小说。」
之后，罗默与他的导师讨论研究计划时，提到「多层太阳能电池」，也就是将几种不同的太阳能电池堆栈在一起，以更好地利用完整的太阳光谱。这时，我灵机一动，「也许多层太阳能电池，就可以解决帕兰克教授的研究瓶颈」
他进一步解释，太阳能板本身就是一种吸收光线产生电讯号的设备，所以从本质上来说，它与感光组件的原理是差不多的，只是功能更单纯。「他们需要在每个像素中互连三个微型硅质太阳能电池，以将电压增加到足以刺激神经元的讯号值」
他说：「虽然我们不能轻易地堆栈硅太阳能电池，因为它不透光，但是新的半导体材料，比如砷化镓(GaAs)或是磷化镓铟 (GaInP)就不错。虽然它们不像硅那么便宜，但更容易调整。」
罗默在完成研究计划后，向澳洲研究委员会提出「潜力研究奖」（DECRA）申请，获得了该计划的资金。
该技术目前处于概念验证阶段。下一步是将微小的太阳能电池转变为精确视觉所需的微小像素。
罗莫说：「到目前为止，我们已经成功地将两个1平方公分的薄型太阳能电池迭放，并取得了一些良好的效果。当然这个尺寸还是太大，放不进眼睛里，所以末来的目标是2平方公厘，像素尺寸约为 50 微米。
目前该设备的感光效果还不够，只有靠雷射照射时才能运作，也只能出现分辨率相当低的黑白影像。
罗莫说：「为了增加功率，我们也在设计辅助智能眼镜，它们有更大的感光效果，可以与生化电子眼协同工作，将光线讯号放大到刺激眼睛神经元所需的强度。」
留言微信公众号《自然学英语LearnNaturally》，可咨询更多！
